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  • 2020-2022
  • 1995-1999  (52)
  • 1985-1989  (47)
  • 1955-1959  (4)
  • 1935-1939
  • 1890-1899
  • Agrobacterium
  • 1
    Digitale Medien
    Digitale Medien
    A Modular Vector for Agrobacterium Mediated Transformation of Wheat (1999)
    Springer
    Plant molecular biology reporter 17 (1999), S. 323-331 
    Details
    ISSN: 1572-9818
    Schlagwort(e): Agrobacterium ; modular vector ; transformation ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Wheat (cv Chinese Spring) tissues were transformed using Agrobacterium tumefasciens and a new plasmid modular vector, pMVTBP. We constructed pMVTBP with unique restriction sites connecting (1) the CaMV 35S promoter, (2) a Kozak sequence, (3) the FLAG epitope, (4) the (His)6 epitope, (5) a coding region (for wheat TATA Binding Protein, wTBP) and (6) the CaMV 35S 3′UTR. This vector thus allows easy exchange of different regulatory or coding sequences. Explants of either germinating mature seeds, or immature embryos, were induced to callus for up to two weeks, treated with virulence-induced bacteria for one hour, then regenerated into plantlets. Transient expression of a GUS reporter gene, assayed at about one week, occurred in 10–12% of calluses. Expression of the FLAG-tagged wTBP was also detected, by immunostaining. Stable expression, by selective growth on geneticin, and by GUS expression at about six weeks, occurred in 1–2% of calluses, quite comparable to that achieved by other methods.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007686408369
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  • 2
    Digitale Medien
    Digitale Medien
    Transgenic almond (Prunus dulcis Mill.) plants obtained by Agrobacterium-mediated transformation of leaf explants (1999)
    Springer
    Plant cell reports 18 (1999), S. 387-393 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Key words Almond ; Prunus ; Transformation ; Agrobacterium ; Adventitious regeneration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Almond (Prunus dulcis Mill.) leaves were transformed with the marker genes gusA (β-glucuronidase) and nptII (neomycin phosphotransferase II) via Agrobacterium-mediated transformation. Bacterial strains and preculture of explants affected efficiency of gene transfer evaluated by transient expression assays. Following transformation, shoots were induced from primary explants on medium without kanamycin and exposed to selection 20 days after cocultivation. From 1419 original leaves, four shoots (A, B, C and D) were obtained that showed amplification of the predicted DNA fragments by polymerase chain reaction (PCR). After micropropagation of these shoots, only those cloned from shoot D gave consistently positive results in histochemical GUS detection and PCR amplification. Southern blot hybridisation confirmed stable transgene integration in clone D, which was also negative in PCR amplification of an Agrobacterium gene. Additional molecular analysis suggested that the remaining three shoots (A, B and C) were chimeric.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002990050591
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  • 3
    Digitale Medien
    Digitale Medien
    Green-fluorescent protein facilitates rapid in vivo detection of genetically transformed plant cells (1999)
    Springer
    Plant cell reports 18 (1999), S. 707-714 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Key words Green-fluorescent protein ; Transformation ; Particle bombardment ; Agrobacterium ; Sugarcane
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Early detection of plant transformation events is necessary for the rapid establishment and optimization of plant transformation protocols. We have assessed modified versions of the green fluorescent protein (GFP) from Aequorea victoria as early reporters of plant transformation using a dissecting fluorescence microscope with appropriate filters. Gfp-expressing cells from four different plant species (sugarcane, maize, lettuce, and tobacco) were readily distinguished, following either Agrobacterium-mediated or particle bombardment-mediated transformation. The identification of gfp-expressing sugarcane cells allowed for the elimination of a high proportion of non-expressing explants and also enabled visual selection of dividing transgenic cells, an early step in the generation of transgenic organisms. The recovery of transgenic cell clusters was streamlined by the ability to visualize gfp-expressing tissues in vitro.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002990050647
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  • 4
    Digitale Medien
    Digitale Medien
    Stable genetic transformation of white pine (Pinus strobus L.) after cocultivation of embryogenic tissues with Agrobacterium tumefaciens (1999)
    Springer
    Molecular breeding 5 (1999), S. 429-440 
    Details
    ISSN: 1572-9788
    Schlagwort(e): transgenic trees ; scaffold attachment region ; Agrobacterium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A genetic transformation procedure for white pine has been developed after cocultivation of embryogenic tissues with Agrobacterium tumefaciens. This efficient transformation procedure led to an average of four independent transformed lines per gram of cocultivated embryogenic tissue and up to 50 transformed lines can be obtained in a routine experiment. Constructs bearing the uidA gene or the green fluorescent protein (GFP) gene were introduced and β-glucuronidase (GUS) activity was followed over time. The expression of the uidA gene was lowest with a 35S-gus-intron construct and was 20-fold higher with a 35S-35S-AMVgus::nptII construct. The addition of scaffold attachment region (SAR) sequences surrounding the gus::nptII fusion did not significantly enhance the GUS activity. Transformed mature somatic embryos have been germinated and plantlets are presently being acclimatized.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1009683605841
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  • 5
    Digitale Medien
    Digitale Medien
    Positive-negative selection and T-DNA stability in Arabidopsis transformation (1999)
    Springer
    Plant molecular biology 39 (1999), S. 83-93 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Arabidopsis ; Agrobacterium ; T-DNA ; CodA ; positive-negative selection ; recombination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have analysed the application of positive-negative selection for the selection of homologous recombination interactions between the chromosome and a T-DNA molecule after transformation of plant cells. Two different genomic loci in a cell suspension of Arabidopsis thaliana were chosen to study gene targeting events. One was the chalcone synthase (CHS) gene present as a single copy and the second an hemizygous chromosomally inserted T-DNA containing the hpt gene, conferring resistance to hygromycin, flanked by CHS sequences. The target lines were transformed with replacement-type T-DNA vectors which contained a positive selectable marker flanked by the regions of the CHS gene and a negative selectable marker to counter-select random insertions. As negative marker we used the Escherichia coli codA gene encoding cytosine deaminase, conferring upon the cells sensitivity to 5-flourocytosine (5-FC). Doubly selected transformants represent 1–4% of the primary transformed cells. Targeting events were not found at the chalcone synthase locus nor at the artificial hpt locus in a total of 4379 doubly selected calli, corresponding to at least 109 475 individual primary transformants. We show by PCR and Southern analysis that the 5-FC resistance in the majority of these cells is associated with substantial deletions of the T-DNA molecule from the right-border end.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006192225464
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  • 6
    Digitale Medien
    Digitale Medien
    Sequence and functional analysis of the left-hand part of the T-region from the nopaline-type Ti plasmid, pTiC58 (1999)
    Springer
    Plant molecular biology 41 (1999), S. 765-776 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; Ti plasmid ; oncogenes ; e gene ; 3′ gene
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The Agrobacterium tumefaciens nopaline strain C58 transfers a large, 29 kb T-DNA into plant cells during infection. Part of this DNA (the `common DNA') is also found on the T-DNA of octopine strains, the remaining DNA is nopaline strain-specific. Up to now, only parts of the C58 T-DNA and related T37 T-DNA have been sequenced. We have sequenced the remainder of the nopaline-specific T-DNA (containing genes a to d) and acs to iaaM. Gene c codes for a new unknown T-DNA protein. Gene a is homologous to the agrocinopine synthase gene. Genes b, c′, d and e are part of a larger family: they are related to the T-DNA genes 5, rolB, lso and 3′. Genes 5, rolB and lso induce or modify plant growth and have been called T-DNA oncogenes. Our studies show that gene 3′ (located on the TR-DNA of octopine strains) is also oncogenic. Although the b–e T-DNA fragment from C58 and its individual genes lack growth-inducing activity, an a-acs deletion mutant was distinctly less virulent on Kalanchoe daigremontiana and showed reduced shoot formation on Kalanchoe tubiflora. Shoot formation could be restored by genes c and c′ in co-infection experiments. Contrary to an earlier report, a C58 e gene deletion mutant was fully virulent on all plants tested.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006370207379
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  • 7
    Digitale Medien
    Digitale Medien
    Evidence of Migration and Endophytic Presence of Agrobacterium tumefaciens in Rose Plants (1999)
    Springer
    European journal of plant pathology 105 (1999), S. 39-50 
    Details
    ISSN: 1573-8469
    Schlagwort(e): Agrobacterium ; crown gall ; systemic infection ; rose ; endophyte
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Agrobacterium tumefaciens was isolated from stem tumors of several rose cultivars showing that the bacterium is the causal agent of aerial galls in rose plants. No differences were observed in the characteristics of the Agrobacterium isolates from crown or aerial galls. Stem inoculation of ten rose cultivars showed that all of them were susceptible to A. tumefaciens but differences in the size of the resulting tumors were observed. The movement of A. tumefaciens in rose plants was demonstrated using two wild type strains and two antibiotic resistant mutants. Three months after inoculation, the inoculated strains were recovered in the roots, crown and below and above the inoculation site but low numbers of pathogenic Agrobacterium cells were isolated. New tumors appeared in 5% of the noninoculated wounds. A. tumefaciens was isolated from the stem at different distances from the tumor in naturally infected plants. In symptomless commercial plants, the isolation from the roots, crown and at different stem levels demonstrated the existence of systemic and latent infections in rose. Direct isolation using a nonselective and selective media with or without a previous enrichment step were efficient methods for isolating tumorigenic Agrobacterium from the different parts of rose plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008660500107
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  • 8
    Digitale Medien
    Digitale Medien
    Origin and evolution of plasmids (1998)
    Springer
    Antonie van Leeuwenhoek 73 (1998), S. 117-126 
    Details
    ISSN: 1572-9699
    Schlagwort(e): riboplasmids ; encapsidation ; pseudovirions ; selfish plasmids ; replicons ; ribozyme ; Agrobacterium ; Rhizobium ; grapevines ; L-tartrate ; lignin ; methoxyphenols ; satellite viruses ; opines ; crown gall ; T-DNA ; origin of replication
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Studies on the origin and evolution of plasmids may provide valuable insights on the promiscuous nature of DNA. The first examples of the selfish nature of nucleic acids are exemplified by primordial oligoribonucleotides which evolved into primitive replicons. The propagation of these molecules were likely patterned after the current viral RNA ribozymes, which have been recently shown to possess RNA synthesizing and template mediated polymerizing capabilities in the absence of proteins. The parasitic nature of nucleic acids is depicted by satellite nucleic acid molecules associated with viruses. The satellites of adenovirus and tobacco ringspot virus serve as established examples: they contain no open reading frames. Comparative analysis of the replication origins of virions and plasmids show them to be conserved, originating from the simplest autocatalytic replicon to highly complex and evolved plasmids, replicating by a rolling circle mechanism. The eventual association of proteins with nucleic acids provided added efficiency and protective advantages for molecular perpetuation. The promiscuous and selfish nature of plasmids is demonstrated by their ability to genetically engineer their host so that the host cell is best able to cope and survive in hostile environments. Survival of the host ensures survival of the plasmid. Sequestering of genes by plasmids occurs when the environmental conditions negatively affect the host. The sequestering mechanism is fundamental and forms the outreach mechanisms to generate and propagate macromolecules of increasing size when necessary for survival. The level of sophistication of plasmids increases with the addition of new genes such as those that allow the host to occupy a specific environment normally inhospitable to the host cell. The vast range of plasmid types which have obtained genes interchangeably reflect the levels of sophistication achieved by these macromolecules. The Ti plasmid in Agrobacterium tumefaciens and the pSym and accessory plasmids in Rhizobium illustrate the level of complexity attained by replicons.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1000652513822
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  • 9
    Digitale Medien
    Digitale Medien
    Transformation and regeneration of Lobelia erinus using Agrobacterium tumefaciens (1998)
    Springer
    Plant cell reports 18 (1998), S. 308-311 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Key words Campanulaceae ; Lobelia erinus ; Transformation ; Agrobacterium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A transformation/regeneration system was developed for the common garden Lobelia (Lobelia erinus). Using an Agrobacterium-based protocol, over 40 transformants have been generated with four different binary vectors. The explant source was hypocotyl-root sections from axenically grown seedlings. Stable transformation was demonstrated by Southern hybridization analysis, β-glucuronidase staining, and transmission of the T-DNA to progeny. This extends the ever-widening range of transformable plant species to the Campanulaceae and will allow molecular studies of development and physiology in this easily cultured and popular garden plant.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002990050577
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  • 10
    Digitale Medien
    Digitale Medien
    Factors affecting soybean cotyledonary node transformation (1998)
    Springer
    Plant cell reports 18 (1998), S. 180-186 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Key words Soybean ; SAAT (sonication assisted Agrobacterium-mediated transformation) ; Agrobacterium ; Transformation ; KYRT1
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Cotyledonary node transformation efficiency was evaluated using a sonication assisted Agrobacterium-mediated transformation (SAAT) protocol, three dissimilar A. tumefaciens strains, and explants derived from 28 diverse cultivars and/or genotypes of soybean [Glycine max (L.) Merr.]. The explants were evaluated at 10 and 45 days after co-cultivation for transformation with a binary vector containing both a GUS-intron gene and an NPTII selectable marker. The best overall strain of A. tumefaciens was determined to be KYRT1 based on stable GUS transformation of soybean cotyledonary node explants measured at the terminal 45 day evaluation point. SAAT did not increase stable transformation at 45 days post co-cultivation. SAAT was determined to significantly decrease shoot proliferation of some genotypes, but it is unclear what effect this may have on the recovery of transformed shoots. Significant differences were also detected between genotypes for transformation and shoot proliferation frequency.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002990050553
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  • 11
    Digitale Medien
    Digitale Medien
    Transgenic peppermint (Mentha×piperita L.) plants obtained by cocultivation with Agrobacterium tumefaciens (1998)
    Springer
    Plant cell reports 17 (1998), S. 165-171 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Key words Peppermint ; Transformation ; Agrobacterium ; GUS ; Transgenic
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The first transgenic peppermint (Mentha×piperita L. cultivar Black Mitcham) plants have been obtained by Agrobacterium-mediated transformation by cocultivation with morphogenically responsive leaf explants. Basal leaf explants with petioles, from leaves closest to the apex of in-vitro-culture-maintained shoots (5 cm), exhibited optimal shoot organogenetic responsiveness on medium supplemented with thidiazuron (8.4 µm). Shoot formation occurred at sites of excision on the leaf blade and petiole either directly from cells of the explant or via a primary callus. Analyses of transient GUS activity data indicated that DNA delivery by microprojectile bombardment was more effective than Agrobacterium infection. However, no transgenic plants were obtained from over 22,000 leaf explants after particle bombardment. Cocultivation of leaf explants with Agrobacterium strain EHA 105 and kanamycin selection produced transgenic plants. Greater transient and stable -glucuronidase (GUS) activities were detected in explants or propagules transformed with the construct where gusA was driven by the pBISN1 promoter rather than a CaMV 35S promoter. Eight plants were subsequently regenerated and verified as transgenic based on detection of the nptII transgene by PCR and Southern blot analyses. The Southern analyses indicated that the plants were derived from eight unique transformation events. All transgenic plants appeared morphologically normal. Analyses of GUS activities in leaves sampled from different portions of these transgenic plants, 10 months after transfer to the greenhouse, indicated that six out of the eight original regenerants were uniformly transformed, i.e., did not exhibit chimeric sectors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002990050372
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  • 12
    Digitale Medien
    Digitale Medien
    Agrobacterium tumefaciens-mediated transformation of Eucalyptus camaldulensis and production of transgenic plants (1998)
    Springer
    Plant cell reports 17 (1998), S. 675-680 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Key words Genetic transformation ; Agrobacterium ; Eucalyptus ; Regeneration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract An efficient system for Agrobacterium-mediated transformation of Eucalyptus camaldulensis and production of transgenic plants was developed. Transformation was accomplished by cocultivation of hypocotyl segments with Agrobacterium tumefaciens containing a binary Ti-plasmid vector harboring chimeric neomycin phosphotransferase and β-glucuronidase (GUS) genes. A modified Gamborg's B5 medium used in this study was effective for both callus induction and regeneration of transgenic shoots. This medium could also effectively maintain the organogenic capability of callus for more than a year. Culturing transgenic shoots in Murashige and Skoog medium supplemented with 0.1 mg ⋅ l–1 benzylaminopurine prior to root induction in rooting medium markedly increased the rootability of shoots that were recalcitrant to rooting. Histochemical assay revealed the expression of the GUS gene in leaf, stem, and root tissues of transgenic plants. Insertion of the GUS gene in the nuclear genome of transgenic plants was verified by genomic Southern hybridization analysis, further confirming the integration and expression of T-DNA in these plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002990050464
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  • 13
    Digitale Medien
    Digitale Medien
    Activity of the CaMV 35S promoter in various parts of transgenic early flowering birch clones (1998)
    Springer
    Plant cell reports 18 (1998), S. 243-248 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Key wordsBetula pendula ; Transformation ; Agrobacterium ; Gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Early flowering together with small size would be useful for various biotechnical or genetic studies on trees. We report here the selection and micropropagation of early flowering birch (Betula pendula) clones (BPM1–12) obtained from seeds of birches bred elsewhere for early flowering. Under conditions that accelerate flowering (a high CO2 level, strong and continuous illumination), the first male inflorescences emerged in 3–5 months, the trees then being 20–80 cm high. Transgenic lines (CaMV 35S-GUS INT) were produced through Agrobacterium-mediated gene transfer from BPM2, BPM5 and JR1/4 (a normally flowering birch). β-Glucuronidase (GUS) activities in the different lines, assayed 1–1.5 years after transformation, varied greatly. During further in vitro culture for 10 months, the activities decreased to 0.3–7% of the original values. GUS activities were detected in all organs studied, including the developing male inflorescences; the highest activity was in the roots.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002990050564
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  • 14
    Digitale Medien
    Digitale Medien
    Transformation of arctic bramble (Rubus arcticus L.) by Agrobacterium tumefaciens (1998)
    Springer
    Plant cell reports 17 (1998), S. 822-826 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Key words Rosaceae ; β-Glucuronidase ; Regeneration ; Agrobacterium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Genetic transformation of arctic bramble (Rubus arcticus L.) was achieved utilizing a Ti-plasmid vector system of Agrobacterium tumefaciens. Internodal stem segments were inoculated with Agrobacterium strain EHA101 carrying a T-DNA with the CaMV 35 S promoter-gus-int marker gene from which β-glucuronidase (GUS) is expressed only in plants. Regenerants were produced on Murashige and Skoog medium. Growth of Agrobacterium was inhibited with cefotaxime. Kanamycin was used as the selective agent for the transformants. Regenerants were assayed by histochemical GUS staining, and by Southern analysis using a gus-int probe. Transgenic arctic bramble plants containing gus-int and expressing GUS were recovered. Expression has been stable for 3 years in micropropagation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002990050491
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  • 15
    Digitale Medien
    Digitale Medien
    CaMV 35S promoter directs β-glucuronidase expression in the laticiferous system of transgenic Hevea brasiliensis (rubber tree) (1998)
    Springer
    Plant cell reports 17 (1998), S. 621-625 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Key wordsHevea brasiliensis ; Agrobacterium ; CaMV 35S ; β-Glucuronidase ; Latex
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Hevea brasiliensis anther calli were genetically transformed using Agrobacterium GV2260 (p35SGUSINT) that harboured the β-glucuronidase (gus) and neomycin phosphotransferase (nptII) genes. β-Glucuronidase protein (GUS) was expressed in the leaves of kanamycin-resistant plants that were regnerated, and the presence of the gene was confirmed by Southern analysis. GUS was also observed to be expressed in the latex and more importantly in the serum fraction. Transverse sections of the leaf petiole from a transformed plant revealed GUS expression to be especially enhanced in the phloem and laticifers. GUS expression was subsequently detected in every one of 194 plants representing three successive vegetative cycles propagated from the original transformant. Transgenic Hevea could thus facilitate the continual production of foreign proteins expressed in the latex.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002990050454
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  • 16
    Digitale Medien
    Digitale Medien
    Genetic transformation and regeneration of mature tissues of woody fruit plants bypassing the juvenile stage (1998)
    Springer
    Transgenic research 7 (1998), S. 51-59 
    Details
    ISSN: 1573-9368
    Schlagwort(e): sweet orange ; Citrus ; woody ; transformation ; Agrobacterium ; mature
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Regeneration and transformation systems from mature plant material of woody fruit species have to be achieved as a necessary requirement for the introduction of useful genes into specific cultivars and the rapid evaluation of resulting horticultural traits. We report here, for the first time, a procedure for genetic transformation and regeneration of mature tissues of woody plants that overcomes the long juvenile periods and high heterozygosity that are characteristic of most of these species. An improved regeneration frequency from mature explants was obtained by invigoration of the plant material through grafting of mature buds on juvenile seedlings. Co-cultivation of the explants in feederplates after inoculation with Agrobacterium tumefaciens resulted in enhanced transformation frequencies. Furthermore, in vitro shoot-tip grafting of the regenerated mature shoots on seedling rootstocks provided a rapid and efficient system for plant production. Citrus is the most extensivel y grown fruit crop worldwide and sweet orange (Citrus sinensis L. Osbeck) accounts for approximately 70% of the Citrus total production. Mature transgenic sweet orange plants have been obtained, which flowered and bore fruit in 14 months
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008855922283
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  • 17
    Digitale Medien
    Digitale Medien
    An efficient protocol for sugarcane (Saccharum spp. L.) transformation mediated by Agrobacterium tumefaciens (1998)
    Springer
    Transgenic research 7 (1998), S. 213-222 
    Details
    ISSN: 1573-9368
    Schlagwort(e): Saccharum ; Agrobacterium ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract This is the first successful report of the recovery of morphologically normal transgenic sugarcane plants from co-cultivation of calluses with Agrobacterium tumefaciens. Transformation frequencies (total of transgenic plants/number of cell clusters) were between 9.4 × 10−3 and 1.15 × 10−2. In our experiments, both LBA4404 (pTOK233) and EHA101 (pMTCA3IG), carrying a super-binary vector or supervirulent strain, respectively, were successful for sugarcane transformation. We found that three main factors: (1) the use of young regenerable calluses as target explants; (2) induction and/or improvement of the A. tumefaciens virulence system with sugarcane cell cultures and (3) pre-induction of organogenesis or somatic-embryogenesis-like sexual embryos, seem to be crucial in order to increase the cells competence for T-DNA transfer process. Patterns generated by Southern hybridization confirmed that T-DNAs were randomly integrated into sugarcane genome without th e persistence of A. tumefaciens in the transgenic plants
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1008845114531
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  • 18
    Digitale Medien
    Digitale Medien
    Agrobacterium tumefaciens-mediated transformation of cauliflower, Brassica oleracea var. botrytis (1998)
    Springer
    Molecular breeding 4 (1998), S. 531-541 
    Details
    ISSN: 1572-9788
    Schlagwort(e): Agrobacterium ; Brassica oleracea ; cauliflower ; regeneration ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract We have developed an efficient and simpler method for genetic transformation and regeneration of cauliflower, Brassica oleracea var. botrytis plants. Explants from 4-day old seedlings were inoculated and cocultivated with Agrobacterium tumefaciens strain LBA4404 harbouring a binary vector with the neomycin phosphotransferase-II gene under the regulatory control of nopaline synthase promoter and terminator sequences, permitting transformed shoots to be selected on kanamycin containing medium. After three months rooted transformed plantlets were successfully transferred and grown under glasshouse conditions. Higher numbers of transformed plants were obtained from cotyledon than hypocotyl explants, presumably indicating cotyledons of cauliflower are more amenable to genetic transformation. Integration and expression of the introduced transgene were analysed by DNA gel blot and PCR analysis and NPT-II expression assay. Factors influencing transformation efficiency include explant age, concentration of bacterium used for infection, duration of infection and cocultivation with Agrobacterium. Transgenic plants of three commercial genotypes of cauliflower were produced using this method. We also show that introduction of antisense Bcp1 (pollen-specific gene) linked to a pollen-specific promoter (Lat52) resulted in the expected sterility of 50% pollen carrying this transgenic construct.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1009658614579
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  • 19
    Digitale Medien
    Digitale Medien
    Investigation of Agrobacterium-mediated transformation of apple using green fluorescent protein: high transient expression and low stable transformation suggest that factors other than T-DNA transfer are rate-limiting (1998)
    Springer
    Plant molecular biology 37 (1998), S. 549-559 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; apple ; GFP ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract To investigate early events of Agrobacterium-mediated transformation of apple cultivars, a synthetic green fluorescent protein gene (SGFP) was used as a highly sensitive, vital reporter gene. Leaf explants from four apple cultivars (‘Delicious’, ‘Golden Delicious’, ‘Royal Gala’ and ‘Greensleeves’) were infected with Agrobacterium EHA101 harboring plasmid pDM96.0501. Fluorescence microscopy indicated that SGFP expression was first detected 48 h after infection and quantitative analysis revealed a high T-DNA transfer rate. Plant cells with stably incorporated T-DNA exhibited cell division and developed transgenic calli, followed by formation of transgenic shoots at low frequencies. The detection of SGFP expression with an epifluorescence stereomicroscope confirmed the effectiveness of SGFP as a reporter gene for detection of very early transformation events and for screening of putative transformants. The efficiency of the transformation and regeneration process decreased ca. 10000-fold from Agrobacterium infection to transgenic shoot regeneration, suggesting that factors other than Agrobacterium interaction and T-DNA transfer are rate-limiting steps in Agrobacterium-mediated transformation of apple.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006041313209
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  • 20
    Digitale Medien
    Digitale Medien
    The use of visual marker genes as cell-specific reporters of Agrobacterium-mediated T-DNA delivery to wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). (1998)
    Springer
    Euphytica 99 (1998), S. 17-25 
    Details
    ISSN: 1573-5060
    Schlagwort(e): Agrobacterium ; barley ; C1/Lc ; GFP ; GUS ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Transfer of T-DNA from Agrobacterium tumefaciens and A. rhizogenes to cells of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) is demonstrated following the inoculation of immature embryos and immature embryo-derived callus. Agrobacterium T-DNA vectors containing the C1/Lc anthocyanin-biosynthesis regulatory genes, the gusA gene or a synthetic green fluorescent protein gene (sgfp-S65T) were constructed from original binary vectors. The visual T-DNA markers were used as cell-autonomous reporters of early Agrobacterium-mediated transformation events in the wheat and barley cells. This localization of the transformed cells revealed a non-random distribution throughout each embryo and callus piece.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1018303102488
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  • 21
    Digitale Medien
    Digitale Medien
    Cre/lox-mediated site-specific integration of Agrobacterium T-DNA in Arabidopsis thaliana by transient expression of cre (1998)
    Springer
    Plant molecular biology 38 (1998), S. 393-406 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; Arabidopsis ; Cre/lox ; recombination ; site-specific integration ; T-DNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The Cre/lox system was used to obtain targeted integration of an Agrobacterium T-DNA at a lox site in the genome of Arabidopsis thaliana. Site-specific recombinants, and not random events, were preferentially selected by activation of a silent lox-neomycin phosphotransferase (nptII) target gene. To analyse the effectiveness of Agrobacterium-mediated transfer we used T-DNA vectors harbouring a single lox sequence (this vector had to circularize at the T-DNA left- and right-border sequences prior to site-specific integration) or two lox sequences (this vector allowed circularization at the lox sequences within the T-DNA either prior to or after random integration, followed by targeting of the circularized vector), respectively. Furthermore, to control the reversibility of the integration reaction, Cre recombinase was provided transiently by using a cotransformation approach. One precise stable integrant was found amongst the recombinant calli obtained after transformation with a double-lox T-DNA vector. The results indicate that Agrobacterium-mediated transformation can be used as a tool to obtain site-specific integration.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006024500008
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  • 22
    Digitale Medien
    Digitale Medien
    Transgenic Populus tremula: a step-by-step protocol for its Agrobacterium-mediated transformation (1997)
    Springer
    Plant molecular biology reporter 15 (1997), S. 219-235 
    Details
    ISSN: 1572-9818
    Schlagwort(e): Agrobacterium ; Populus ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In recent years, Populus species have acquired an important place in basic and applied research of woody plants. The practical role of Populus species in world forestry and their importance to research as a woody-plant model have led to increasing interest in tissue-culture and molecular techniques, as well as the development of transformation procedures for this genus. A simple technical procedure is described here step-by-step, for the first time, as a routine method for transforming Populus tremula using a disarmed Agrobacterium tumefaciens hypervirulent strain. The procedure begins with the inoculation of stem explants with bacterial suspension, followed by a short period of co-cultivation on a highly regenerative medium. Transformed shoots are selected on regeneration medium containing antibiotics and the presence of the inserted target genes is checked using a rapid and efficient PCR test. Selected shoots are transferred to a rooting medium, under the same selection pressure, and propagated via stem cuttings. Selected plants can be hardened and transferred to the green-house within 4 months of inoculation. The method has proven efficient for several gene constructs, selection on Kan or Hyg, and three different Agrobacterium strains.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1007484917759
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  • 23
    Digitale Medien
    Digitale Medien
    Role of the host cell cycle in theAgrobacterium-mediated genetic transformation ofPetunia: Evidence of an S-phase control mechanism for T-DNA transfer (1997)
    Springer
    Planta 201 (1997), S. 160-172 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Leaf mesophyll cells ; Petunia ; Transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Chimeric β-glucuronidase (GUS) gene expression in an efficientAgrobacterium-mediated transformation system utilising mesophyll cells ofPetunia hybrida synchronized with cell cycle phase-specific inhibitors (mimosine and colchicine) was used to show the absolute requirement of S-phase for transfer and/or integration of the transferred DNA (T-DNA). Flow-cytometric analysis of nuclear DNA content and immunohistological detection of bromodeoxyuridine (BrdUrd) incorporation showed that, prior to phytohormone treatment, most (98%) mesophyll cells were at GO-Gl-phase (quiescent phase) and no cell division was occurring. After 48 h and 72 h of phytohormone treatment, there was a rapid increase in S-G2-M-phase populations (〉 75%) and a concomitant decrease (down to 24%) in G0–-G1-phase cells. Assays of GUS showed that maximum transformation (〉 95% of explants) also occurred after this period. Our data showed that mimosine and colchicine blocked the mesophyll cells at late Gl-phase and M-phase, respectively. No transformation (= GUS expression) was observed in phytohormone-treated cells inhibited in late G1 by mimosine. However, after removal of mimosine, 82% of the explants were transformed, indicating the non-toxic and reversible effect of the inhibitor. On the other hand, a relatively high transformation frequency (65% of explants) was observed after blocking the cell cycle at M-phase with colchicine. However, only transient, but no stable, gene expression (= kanamycin-resistant callus formation) was observed in colchicine-treated M-phase-arrested cells. Similarly, endoreduplication of nuclear DNA, which occurred during the 48 h of phytohormone treatment in some mesophyll cells and cells located along the minor veins in the leaf explants, resulted in transient GUS expression only. These observations indicate a direct correlation between endoreduplication and transient GUS gene expression. Obviously, for stable GUS gene expression, cell division and proliferation are required, indicating that both DNA duplication (S-phase) and cell division (M-phase) are strongly related to stable transformation. We propose that the present system should facilitate further dissection of the process of T-DNA integration in the host genome and therefore should aid in developing new strategies for transformation of recalcitrant plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01007700
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  • 24
    Digitale Medien
    Digitale Medien
    Expression and inheritance of foreign genes in transgenic peanut plants generated byAgrobacterium-mediated transformation (1997)
    Springer
    Plant cell reports 16 (1997), S. 541-544 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Transgenic peanut ; Agrobacterium ; Transformation ; Transgene expression ; Transgene inheritance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract To evaluate and characterize the stability of traits transferred viaAgrobacterium transformation, foreign gene expression must be examined in sexually derived progeny. The objective of this study was to analyze three transgenic peanut plants, 1-10, 12-1, and 17-1, for the inheritance and expression of their foreign genes. Segregation ratios for the introduced genes in T2 plants gave either 100% or 3:1 expression of the β-glucuronidase (GUS) gene, demonstrating recovery of both homozygous and heterozygous T1 plants. Fluorometric GUS assay in T1 and T2 generations of all three plants showed that the GUS gene was stably expressed in the progeny. DNA analyses showed 100% concordance between the presence of the foreign gene and enzyme activity. Our results demonstrate that transgenes in peanut introduced byAgrobacterium can be inherited in a Mendelian manner.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01142320
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  • 25
    Digitale Medien
    Digitale Medien
    Isolation of new 6-methylnicotinic-acid-degrading bacteria, one of which catalyses the regioselective hydroxylation of nicotinic acid at position C2 (1997)
    Springer
    Archives of microbiology 168 (1997), S. 355-361 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Key words 6-Methylnicotinic acid ; 2-Hydroxy-6-methylnicotinic acid ; Nicotinic acid ; 2-Hydroxynicotinic acid ; Ralstonia ; Burkholderia ; Paenibacillus ; Agrobacterium ; Rhizobium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract 2-Hydroxynicotinic acid is an important building block for herbicides and pharmaceuticals. Enrichment strategies to increase the chances of finding microorganisms capable of hydroxylating at the C2 position and to avoid the degradation of nicotinic acid via the usual intermediate, 6-hydroxynicotinic acid, were used. Three bacterial strains (Mena 23/3–3c, Mena 25/4–1, and Mena 25/ 4–3) were isolated from enrichment cultures with 6-methylnicotinic acid as the sole source of carbon and energy. Partial characterization of these strains indicated that they represent new bacterial species. All three strains completely degraded 6-methylnicotinic acid, and evidence is presented that the first step in the degradation pathway of strain Mena 23/3–3c is hydroxylation at the C2 position. Resting cells of this strain grown on 6-methylnicotinic acid also hydroxylated nicotinic acid at the C2 position, but did not further degrade the product. Strain Mena 23/ 3–3c showed the highest degree of 16S rRNA sequence similarity to members of the genera Ralstonia and Burkholderia.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002030050509
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  • 26
    Digitale Medien
    Digitale Medien
    Excision of the maize transposable element Ac in periclinal chimeric leaves of 35S-Ac-rolC transgenic aspen-Populus (1997)
    Springer
    Plant molecular biology 33 (1997), S. 1097-1103 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Ac ; Agrobacterium ; periclinal chimera ; rolC ; transgenic Populus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The transposable element Ac from maize, in combination with the phenotypic selectable marker rolC, was employed in transformation experiments of a hybrid aspen clone. A number of transgenic clones exhibited light-green sectors on green leaves. In vitro regeneration from leaves showing a high number of light-green spots resulted in R2 plants, which also showed light-green sectored leaves. However, only one out of 385 regenerated plants obtained showed green leaves. Both PCR and northern analysis indicated Ac excision and restoration of rolC expression. In Southern blot analysis of this green plant additional bands were observed as compared to the original R1 plant. The occurrence of these bands and a suggested Ac excision in the non-green L1-epidermal layer leading to periclinal chimerism of this plant is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1005788706864
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  • 27
    Digitale Medien
    Digitale Medien
    Tapetum-specific expression of theOsg6B promoter-β-glucuronidase gene in transgenic rice (1997)
    Springer
    Plant cell reports 16 (1997), S. 363-367 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Agrobacterium ; Tapetum-specific promoter ; Transformation ; Rice
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The promoter of an anther tapetum-specific gene,Osg6B, was fused to aβ-glucuronidase (GUS) gene and introduced into rice byAgrobacterium-mediated gene transfer. Fluorometric and histochemical GUS assay showed that GUS was expressed exclusively within the tapetum of anthers from the uninucleate microspore stage (7 days before anthesis) to the tricellular pollen stage (3 days before anthesis). This is the first demonstration of an anther-specific promoter directing tapetum-specific expression in rice.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01146774
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  • 28
    Digitale Medien
    Digitale Medien
    Expression and inheritance of foreign genes in transgenic peanut plants generated by Agrobacterium-mediated transformation (1997)
    Springer
    Plant cell reports 16 (1997), S. 541-544 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Key words Transgenic peanut ; Agrobacterium ; Transformation ; Transgene expression ; Transgene inheritance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract To evaluate and characterize the stability of traits transferred via Agrobacterium transformation, foreign gene expression must be examined in sexually derived progeny. The objective of this study was to analyze three transgenic peanut plants, 1-10, 12-1, and 17-1, for the inheritance and expression of their foreign genes. Segregation ratios for the introduced genes in T2 plants gave either 100% or 3:1 expression of the β-glucuronidase (GUS) gene, demonstrating recovery of both homozygous and heterozygous T1 plants. Fluorometric GUS assay in T1 and T2 generations of all three plants showed that the GUS gene was stably expressed in the progeny. DNA analyses showed 100% concordance between the presence of the foreign gene and enzyme activity. Our results demonstrate that transgenes in peanut introduced by Agrobacterium can be inherited in a Mendelian manner.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01142320
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  • 29
    Digitale Medien
    Digitale Medien
    Genetic transformation of Populus genotypes with different chimaeric gene constructs: transformation efficiency and molecular analysis (1997)
    Springer
    Transgenic research 6 (1997), S. 111-121 
    Details
    ISSN: 1573-9368
    Schlagwort(e): Ac ; Agrobacterium ; aspen ; Populus ; transformation ; transposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Aspen (Populus tremula) and hybrid aspen (P. tremula × P. tremuloides) were transformed with different gene constructs using two types of promoter. The aim was to determine the influence of the reporter gene rolC, controlled by promoters of viral or plant origin, on genetic and morphologic expression of different transgenic aspen clones. An improved transformation method using leaf discs was developed, by which putative transgenic plantlets were regenerated at high efficiencies (up to 34%) on kanamycin-containing medium. Transgenic aspen carrying the rolC gene from Agrobacterium rhizogenes under control of the cauliflower-35S-promoter are reduced in size with smaller leaves, whereas aspen transgenic for the same rolC gene, but under control of the light inducible rbcS promoter from potato, are only slightly reduced in size compared to untransformed controls. However, all clones carrying 35S-rolC and rbcS-rolC genes revealed light-green colouration of leaves when compared to untransformed aspen. Owing to this special feature, constructs were used in which expression of the rolC gene was inhibited by insertion of a transposable element, Ac, from maize. Transgenic aspen transformed with the 35S-Ac-rolC and rbcS-Ac-rolC genes were morphologically similar to untransformed aspen, but out of 54 independently regenerated 35S-Ac-rolC transgenic aspen clones, 30 clones showed light-green/dark green variegated leaves. In contrast, out of 19 independently transformed rbcS-Ac-rolC aspen clones, only two clones revealed light-green/dark green variegated leaves. The role of bacterial strains in transformation, and molecular genetics of transgenic aspen plants (including the function of the transposable element, Ac, in the aspen genome) are discussed
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1018421620040
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  • 30
    Digitale Medien
    Digitale Medien
    Agrobacterium rhizogenes and A. tumefaciens co-transformation to obtain grapevine hairy roots producing the coat protein of grapevine chrome mosaic nepovirus (1997)
    Springer
    Plant cell, tissue and organ culture 49 (1997), S. 53-62 
    Details
    ISSN: 1573-5044
    Schlagwort(e): Agrobacterium ; coat protein ; grapevine ; hairy root ; nepovirus ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Hairy root cultures of grapevine were obtained from plantlets co-inoculated by virulent Agrobacterium rhizogenes strains and disarmed A. tumefaciens strains harbouring the binary vectors pKHG4 and pKVHG 2+. These plasmids contain the nptII, hpt and gus genes and differ for the presence of the gene encoding for the grapevine chrome mosaic virus coat protein. For the cultivar ‘Gravesac’, 72% of the excised root tips initiated hairy root cultures on growth regulator-free media. According to the nature of the strains used in co-inoculation, co-transformation frequencies of the hairy root clones ranged from 4 to 16%. Co-transformed roots showed resistance to kanamycin and hygromycin but responses varied from clone to clone. Fluorometric GUS expression and GCMV coat protein production showed a large variability among hairy root clones co-transformed by pKHVG2+. Though the presence of gus, nptII and GCMV coat protein genes was checked by polymerase chain reaction and Southern blotting, it was difficult to establish a clear relationship between expression of the different transgenes. The regeneration of plants was not achieved, but the possibility to graft in vitro transgenic roots to non transformed shoot systems could permit rapid testing of the resistance induced by nepovirus coat protein in roots of cultivars that are recalcitrant to A. tumefaciens-mediated transformation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1005854212592
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  • 31
    Digitale Medien
    Digitale Medien
    Isolation and identification of N2-fixing microorganisms from the rhizosphere of Capparis spinosa (L.) (1997)
    Springer
    Plant and soil 197 (1997), S. 19-23 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Agrobacterium ; Capparis spinosa ; Comamonas ; N2 fixation ; Pseudomonas ; rhizosphere ; Sphingobacterium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Four bacterial strains, Pseudomonas stutzeri var. mendocina, Comamonas sp., Agrobacterium tumefaciens biovar. 2 and Sphingobacterium sp., isolated from the rhizosphere of wild-grown caper (Capparis spinosa L.) plants were able to fix N2 as shown by their growth in nitrogen-free medium and by the acetylene reduction test. P. stutzeri var. mendocina and Comamonas sp. contained DNA homologous to the Klebsiella pneumoniae M5a1 nifHDK genes. No hybridization was found with total DNA from either A. tumefaciens biovar. 2 or Sphingobacterium sp. using nifHDK probes from either K. pneumoniae or Rhizobium meliloti.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1004211909641
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  • 32
    Digitale Medien
    Digitale Medien
    SAAT: sonication-assisted Agrobacterium-mediated transformation (1997)
    Springer
    Transgenic research 6 (1997), S. 329-336 
    Details
    ISSN: 1573-9368
    Schlagwort(e): Agrobacterium ; SAAT ; sonication ; transformation ; wounding
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Plant transformation via Agrobacterium can be limited by both host specificity and the inability of Agrobacterium to reach the proper cells in the target tissue. Described here is a new and efficient Agrobacterium-based transformation technology that overcomes these barriers and enhances DNA transfer in such diverse plant groups as dicots, monocots, and gymnosperms. This new technology, called sonication-assisted Agrobacterium-mediated transformation (SAAT), involves subjecting the plant tissue to brief periods of ultrasound in the presence of Agrobacterium. Scanning electron and light microscopy reveal that SAAT treatment produces small and uniform fissures and channels throughout the tissue allowing the Agrobacterium easy access to internal plant tissues. Unlike other transformation methods, this system has the potential to transform meristematic tissue buried under several cell layers. SAAT increases transient transformation efficiency in several different plant tissues including leaf tissue, immature cotyledons, somatic and zygotic embryos, roots, stems, shoot apices, embryogenic suspension cells and whole seedlings. A 100- to 1400-fold increase in transient β- glucuronid ase expression has been demonstrated in various tissues of soybean, Ohio buckeye, cowpea, white spruce, wheat and maize. Stable transformation of both soybean and Ohio buckeye has been obtained using SAAT of embryogenic suspension culture tissues. For soybean, SAAT treatment was necessary to obtain stable transformation with this tissue
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1018470930944
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  • 33
    Digitale Medien
    Digitale Medien
    Matrix attachment regions (MARs) enhance transformation frequency and transgene expression in poplar (1997)
    Springer
    Transgenic research 6 (1997), S. 415-420 
    Details
    ISSN: 1573-9368
    Schlagwort(e): GUS ; matrix attachment regions ; Populus ; transformation ; transgene expression ; Agrobacterium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We tested the value of a matrix attachment region (MAR) fragment derived from a tobacco gene for increasing the frequency of Agrobacterium-mediated transformation. A binary vector that carried a GUS reporter gene containing an intron and an nptII gene was modified to contain flanking MAR elements within the T-DNA borders. Vectors containing or lacking MARs were then used to transform tobacco, a readily transformabl e poplar clone (Populus tremula × P. alba), and a recalcitrant poplar clone (Populus trichocarpa × P. deltoides). MARs increased GUS gene expression approximately 10-fold in the two hybrid poplar clones and twofold in tobacco one month after cocultivation with Agrobacterium; MARs also increased the frequency of kanamycin-resistant poplar shoots recovered
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1018439518649
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  • 34
    Digitale Medien
    Digitale Medien
    Transgenic plant production mediated by Agrobacterium in Indica rice (1996)
    Springer
    Plant cell reports 15 (1996), S. 727-730 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Acetosyringone ; Agrobacterium ; Indica rice ; Oryza sativa L. ; Transgenic plants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A reproducible system has been developed for the production of transgenic plants in indica rice using Agrobacterium-mediated gene transfer. Three-week-old scutella calli served as an excellent starting material. These were infected with an Agrobacterium tumefaciens strain EHA101 carrying a plasmid pIG121Hm containing genes for β-glucuronidase (GUS) and hygromycin resistnace (HygR). Hygromycin (50 mg/l) was used as a selectable agent. Inclusion of acetosyringone (50μM) in the Agrobacterium suspension and co-culture media proved to be indispensable for successful transformation. Transformation efficiency of Basmati 370 was 22% which was as high as reported in japonica rice and dicots. A large number of morphologically normal, fertile transgenic plants were obtained. Integration of foreign genes into the genome of transgenic plants was confirmed by Southern blot analysis. GUS and HygR genes were inherited and expressed in R1 progeny. Mendelian segregation was observed in some R1 progeny.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00232216
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  • 35
    Digitale Medien
    Digitale Medien
    Transient expression of uidA constructs in in vitro onion (Allium cepa L.) cultures following particle bombardment and Agrobacterium-mediated DNA delivery (1996)
    Springer
    Plant cell reports 15 (1996), S. 958-962 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Transformation ; particle bombardment ; Agrobacterium ; Allium cepa.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Particle bombardment and Agrobacterium-mediated DNA delivery into immature embryos and microbulbs were used to investigate the expression of the uidA gene in in vitro onion cultures. Both methods were successful in delivering DNA and subsequent uidA expression was observed. Optimal transient β-glucuronidase activity was observed in immature embryos that had been pre-cultured for three days and bombarded at a distance of 3 cm from the stopping plate, under 25 in Hg vacuum, using 900–1300 psi rupture discs. The CaMV35S-uidA gene construct gave five fold higher transient β-glucuronidase activity than the uidA gene construct regulated by any of four other promoters initially chosen for high experession in monocotyledonous tissues.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00231596
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  • 36
    Digitale Medien
    Digitale Medien
    Production of an extracellular polysaccharide byAgrobacterium sp DS3 NRRL B-14297 isolated from soil (1996)
    Springer
    Journal of industrial microbiology and biotechnology 16 (1996), S. 129-133 
    Details
    ISSN: 1476-5535
    Schlagwort(e): extracellular polysaccharide ; Agrobacterium ; viscous polysaccharide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Abstract A bacterium isolated from soil and identified asAgrobacterium sp produced a water-soluble extracellular polysaccharide capable of producing highly viscous solutions. Gas chromatographic analysis revealed a sugar composition of glucose, galactose and mannose in the molar ratio of 7.5∶2.4∶1, together with 3.7% (w/w) pyruvic acid. Methylation analyses showed the presence of (1→3)-, (1→4)- and (1→6)-linked glucose, (1→3)- and (1→4, 1→6)-linked galactose and a small portion of (1→3)-linked mannose residues. Succinic acid was not present. The molecular weight of the polysaccharide was estimated by light scattering to be 2×106 Da. The viscosity of solutions containing the polysaccharide remained constant from pH 3 to 11, and decreased by 50% when heated from 5 to 55°C. Maximum yield of the polysaccharide, 20 g L−1, was reached in 48 h at 30°C incubation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01570073
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  • 37
    Digitale Medien
    Digitale Medien
    Agrobacterium tumefaciens-mediated transformation of japonica and indica rice varieties (1996)
    Springer
    Planta 199 (1996), S. 612-617 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; indica rice ; Inheritance ; Japonica rice ; Oryza ; Transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Genetic transformation of rice (Oryza sativa L.) mediated by Agrobacterium ttumefaciens has been confirmed for japonica varieties and extended to include the more recalcitrant indica varieties. Immature embryos were inoculated with either A. tumefaciens At656 (pCNL56) or LBA4404 (pTOK233). Experimental conditions were developed initially for immature embryos treated with strain At656, based upon both transient and stable β-glucuromdase (GUS) activities. However, plant regeneration following selection on G418 (pCNL56 contained the nptII gene) did not occur. Using the same basic protocol, but inoculating immature embryos of rice with LBA4404 (pTOK233), resulted in efficient (about 27%) production of transgenic plants of the japonica variety, Radon, and an acceptable efficiency (from 1–5%) for the indica varieties IR72 and TCS10. Transformation was based upon resistance to hygromycin (pTOK233 contains the hpt gene), the presence of GUS activity (from the gusA gene), Southern blots for detection of the integrated gusA gene, and transmission of GUS activity to progeny in a Mendelian 3:1 segregation ratio. Southern blots indicated two to three copies of the gene integrated in most transformants. Transgenic plants of both the japonica and indica varieties were self-fertile and comparable in this respect to seed-grown plants. Key factors facilitating the transformation of rice by Agrobacterium tumefaciens appeared to be the use of embryos as the expiant, the use of hygromycin as the selection agent (which does not interfere with rice regeneration), the presence of extra copies of certain vir genes on the binary vector of pTOK233, and maintaining high concentrations of acetosyringone for inducing the vir genes during co-cultivation of embryos with Agrobacterium.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00195194
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  • 38
    Digitale Medien
    Digitale Medien
    Sequence and characterisation of a ribosomal RNA operon from Agrobacterium vitis (1996)
    Springer
    Molecular genetics and genomics 251 (1996), S. 99-107 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Key words Ribosomal genes ; Agrobacterium ; Evolution ; 23S rRNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  One of the four ribosomal RNA operons (rrnA) from the Agrobacterium vitis vitopine strain S4 was sequenced. rrnA is most closely related to the rrn operons of Bradyrhizobium japonicum and Rhodobacter sphaeroides and carries an fMet-tRNA gene downstream of its 5S gene, as in the case of R. sphaeroides. The 16S rRNA sequence of S4 differs from the A. vitis K309 type strain sequence by only one nucleotide, in spite of the fact that S4 and K309 have very different Ti plasmids. The predicted secondary structure of the S4 23S rRNA shows several features that are specific for the alpha proteobacteria, and an unusual branched structure in the universal B8 stem. The 3′ ends of the three other rrn copies of S4 were also cloned and sequenced. Sequence comparison delimits the 3′ ends of the four repeats and defines two groups: rrnA/rrnB and rrnC/rrnD.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02174350
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  • 39
    Digitale Medien
    Digitale Medien
    Transformation ofBrassica oleracea L.: a critical review (1996)
    Springer
    Molecular breeding 2 (1996), S. 185-210 
    Details
    ISSN: 1572-9788
    Schlagwort(e): Brassica oleracea ; Agrobacterium ; transformation ; direct gene transfer ; regeneration ; virulence ; flowering ; rol genes ; transgene expression ; transgene inactivation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Brassica oleracea is a highly polymorphic species encompassing a wide range of important vegetable and fodder crops. Gene transfer into cultivated forms of this species requires reproducible and efficient methods for genetic transformation and plant regeneration. In this review, we have collated the research experience on transformation ofB. oleracea to highlight the problems encountered. Most research effort has been directed at developingAgrobacterium-mediated transformation methods with relatively little emphasis to date on direct gene transfer techniques. Common procedures for the transformation ofB. oleracea have not emerged, due to the inherent variability between and amongst genotypes. Future progress would be facilitated by the use of genetically fixed material, such as double-haploid or inbred lines, to reduce variation of response within genotypes and would avoid the need for cultivar-specific transformation protocols if responsive lines amenable to crossing with cultivated forms could be identified. The principal difficulties relate to combining efficient plant regeneration with gene transfer. Methods that enhance bacterial virulence and increase the proportion of cells susceptible to transformation and competent for regeneration are discussed. Inefficient selection is a major cause of poor transformation frequencies inB. oleracea and has resulted in the regeneration of chimeric plants uponAgrobacterium tumefaciens-mediated transformation. Promising results have been obtained withAgrobacterium rhizogenes-mediated transformation but the impact of therol genes on flowering of primary transformants has not yet been fully assessed. Strategies to reduce the deleterious effects of therol genes on flowering are discussed. Few agronomically useful characters have been introduced, the majority of research having been confined to the introduction of marker and reporter genes; possible candidate genes are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00564197
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  • 40
    Digitale Medien
    Digitale Medien
    Sequence and characterisation of a ribosomal RNA operon fromAgrobacterium vitis (1996)
    Springer
    Molecular genetics and genomics 251 (1996), S. 99-107 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Ribosomal genes ; Agrobacterium ; Evolution ; 23S rRNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract One of the four ribosomal RNA operons (rrnA) from theAgrobacterium vitis vitopine strain S4 was sequenced.rrnA is most closely related to therrn operons ofBradyrhizobium japonicum andRhodobacter sphaeroides and carries an fMet-tRNA gene downstream of its 5S gene, as in the case ofR. sphaeroides. The 16S rRNA sequence of S4 differs from theA. vitis K309 type strain sequence by only one nucleotide, in spite of the fact that S4 and K309 have very different Ti plasmids. The predicted secondary structure of the S4 23S rRNA shows several features that are specific for the alpha proteobacteria, and an unusual branched structure in the universal B8 stem. The 3′ ends of the three otherrrn copies of S4 were also cloned and sequenced. Sequence comparison delimits the 3′ ends of the four repeats and defines two groups:rrnA/rrnB andrrnC/rrnD.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02174350
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  • 41
    Digitale Medien
    Digitale Medien
    Corresponding 16S rRNA gene segments in Rhizobiaceae and Aeromonas yield discordant phylogenies (1996)
    Springer
    Plant and soil 186 (1996), S. 69-74 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Agrobacterium ; population genetics ; Rhizobium ; systematics ; taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Previous evidence has indicated that the 16S rRNA genes in certain species of Aeromonas may have a history of lateral transfer and recombination. A comparative analysis of patterns of 16S nucleotide sequence polymorphism among species of Rhizobium and Agrobacterium was conducted to determine if there is similar evidence for chimeric 16S genes in members of the Rhizobiaceae. Results from phylogenetic analyses and comparison of patterns of nucleotide sequence polymorphism in portions of rhizobial 16S genes revealed the same type of segment-dependent polymorphic site partitioning that was previously reported for Aeromonas. These results support the hypothesis that certain 16S segments in rhizobia may have a history of lateral transfer and recombination.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00035057
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  • 42
    Digitale Medien
    Digitale Medien
    Identification of Agrobacterium and Rhizobium species based on cellular fatty acid composition (1996)
    Springer
    Plant and soil 184 (1996), S. 143-158 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Agrobacterium ; FAME ; fatty acid analysis ; rapid identification ; Rhizobium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The increasing number of phylogenetically defined species in the genera Agrobacterium, Rhizobium and Sinorhizobium suggests a need for a rapid identification method which will distinguish between these species. We have examined 65 strains of Agrobacterium representing: A. tumefacies, (34); A. rhizogenes, (16) A. vitis, (10) A. rubi (2) and some unclassified strains, and 150 strains of Rhizobium and Sinorhizobium representing: R. etli (21); R. galegae (20); R. huakuii (17); R. leguminosarum (20); R. loti (16); R. topici (18); S. fredii (19); and S. meliloti (20). Fatty acid methyl esters (FAME) were obtained from each strain, as previously described, and analysed by gas-chromatography using the MIDI Hewlett-Packard Microbial Identification System (MIS). Fatty acid profiles were recorded, characteristic fatty acids noted and the overall similarities between fatty acid profiles for each species calculated. Relationships between species were also derived from the fatty acid data by principal component analysis. This showed overlapping clusters for strains of R. leguminosarum and R. etli, R. topici and A. rhizogenes and S. fredii and S. meliloti within one supercluster. Strains of A. tumefaciens, A rubi, A. vitis and R. galegae formed a second supercluster while R. loti and R. huakuii strains formed a third cluster well separated from all the other strains. The fatty acid profiles were used to correctly identify at least 94% of the strains representing each species in the collection except R. etli. R. etli strains (23.8%) were misidentified as R. leguminosarum. This was attributed to the high similarity (44.7%) between R. etli and R. leguminosarum. It is concluded that whole cell fatty acid analysis should form part of the polyphasic description of new species of root nodule bacteria, with the proviso that growth conditions and analytical methods be carefully standardized. It is suggested that FAME-MIS system and the database we have compiled provide a basis for future development.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00029284
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  • 43
    Digitale Medien
    Digitale Medien
    Agrobacterium-mediated transformation of Javanica rice (1996)
    Springer
    Molecular breeding 2 (1996), S. 267-276 
    Details
    ISSN: 1572-9788
    Schlagwort(e): Agrobacterium ; Javanica rice ; regeneration ; rice ; TAIL-PCR ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Difficulties frequently encountered using direct DNA transfer methods for transformation of Javanica varieties of rice (Oryza sativa L.) have limited the application of biotechnology to these varieties. We now reportAgrobacterium-mediated transformation of Javanica cultivars Gulfmont and Jefferson that are, respectively, widely used or about to enter commercial cultivation in the southern USA. Vigorous, phenotypically normal, fertile plants expressing both the selectable marker and the gene of interest were obtained. Southern analysis showed that only one or two copies of the T-DNA insert were present. Sequence analysis of right border fragments of one line confirmed that insertion was into a coding region of rice nuclear DNA. This analysis also revealed the presence of relatively short regions of permuted T-DNA border sequences, similar to those found afterAgrobacterium-mediated transformation of dicots. Progeny analysis of lines bearing two copies showed co-segregation, indicating that they were located relatively closely on the same chromosome. The introduced genes were transmitted to the R1 and R2 generations in a Mendelian fashion, confirming the suitability of this approach for biotechnological improvement of elite rice cultivars.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00564204
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  • 44
    Digitale Medien
    Digitale Medien
    5′-Regulatory region of Agrobacterium tumefaciens T-DNA gene 6b directs organ-specific, wound-inducible and auxin-inducible expression in transgenic tobacco (1995)
    Springer
    Plant molecular biology 29 (1995), S. 1299-1304 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; gene 6b ; phytohormonal regulation of expression ; T-DNA promoter
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The regulatory activity of a 826 bp DNA fragment located upstream of the pTiBo542 TL-DNA gene 6b coding region was analysed in transgenic tobacco, using β-glucuronidase (gus) as a reporter gene. The region was shown to drive organ-specific, wound- and auxin-inducible expression of the reporter, the effect being dependent on the type and concentration of auxin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00020470
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  • 45
    Digitale Medien
    Digitale Medien
    The three-dimensional structure of vascular tissues in Agrobacterium tumefaciens-induced crown galls and in the host stems of Ricinus communis L. (1995)
    Springer
    Planta 196 (1995), S. 597-605 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Crown gall ; Fiber ; Phloem anastomoses ; Phloem and xylem differentiation ; Phytohormones (auxin, cytokinin, ethylene, gibberellin) ; Ray differentiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The three-dimensional pattern of phloem and xylem in 10-d-to two-month-old tumors induced by Agrobacterium tumefaciens (C58) and in adjacent Ricinus communis L. stem tissues was studied in thick sections by clearing with lactic acid and by staining with lacmoid. The crown galls contained two types of vascular strands: treelike branched bundles, which developed towards the tumor surface in fast-growing regions, and globular bundles in the slowly developing parts. Both types of vascular bundles contained xylem and phloem and were continuous with the vascular system of the host plant. The tumor bundles were interconnected by a dense net of phloem anastomoses, consisting of sieve tubes but no vessels. These vascular patterns reflect the apparent synthesis sites, concentration gradients and flow pathways of the plant hormones additionally produced in the tumors upon expression of the T-DNA-encoded genes. The A. tumefaciens-induced crown gall affected vascular differentiation in the host stem. In the basipetal direction, the tumor induced more xylem differentiation directly below it, where the crown-gall bundles joined the vascular system of the host. In the centripetal direction, the crown gall caused the development of pathologic xylem characterized by narrow vessels, giant rays and absence of fibers. On the other hand, most probably as a consequence of its gibberellic acid content, the host plant stimulated a local differentiation of regenerative phloem and xylem fibers with unique ramifications, only at the base of the tumor. However, fibers were absent from the main body of the crown gall. The study shows that A. tumefaciens-induced crown galls are characterized by a sophisticated network of vascular tissues in the tumor and are accompanied by a perturbated vessel system in the host. The hormonal mechanisms controlling vascular differentiation in the tumor and neighboring host tissues are discussed. In addition, the “gall constriction hypothesis” is proposed for explaining the mechanism which gives priority in water supply to the growing gall over the host shoot.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00203661
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  • 46
    Digitale Medien
    Digitale Medien
    The effect of auxin on cytokinin levels and metabolism in transgenic tobacco tissue expressing an ipt gene (1995)
    Springer
    Planta 196 (1995), S. 84-94 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Auxin ; Cytokinin metabolism ; Cytokinin oxidase ; ipt gene ; Nicotiana (cytokinin)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The ipt gene from the T-DNA of Agrobacterium tumefaciens was transferred to tobacco (Nicotiana tabacum L.) in order to study the control which auxin appears to exert over levels of cytokinin generated by expression of this gene. The transgenic tissues contained elevated levels of cytokinins, exhibited cytokinin and auxin autonomy and grew as shooty calli on hormone-free media. Addition of 1-naphthylacetic acid to this culture medium reduced the total level of cytokinins by 84% while 6-benzylaminopurine elevated the cytokinin level when added to media containing auxin. The cytokinins in the transgenic tissue were labelled with 3H and auxin was found to promote conversion of zeatin-type cytokinins to 3H-labelled adenine derivatives. When the very rapid metabolism of exogenous [3H]zeatin riboside was suppressed by a phenylurea derivative, a noncompetitive inhibitor of cytokinin oxidase, auxin promoted metabolism to adenine-type compounds. Since these results indicated that auxin promoted cytokinin oxidase activity in the transformed tissue, this enzyme was purified from the tobacco tissue cultures. Auxin did not increase the level of the enzyme per unit tissue protein, but did enhance the activity of the enzyme in vitro and promoted the activity of both glycosylated and non-glycosylated forms. This enhancement could contribute to the decrease in cytokinin level induced by auxin. Studies of cytokinin biosynthesis in the transgenic tissues indicated that trans-hydroxylation of isopentenyladenine-type cytokinins to yield zeatin-type cytokinins occurred principally at the nucleotide level.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00193221
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  • 47
    Digitale Medien
    Digitale Medien
    Variability in the response toPseudomonas solanacearum of transgenic lines of potato carrying a cecropin gene analogue (1995)
    Springer
    Potato research 38 (1995), S. 371-378 
    Details
    ISSN: 1871-4528
    Schlagwort(e): bacterial wilt ; resistance ; transformation ; Agrobacterium ; S. tuberosum L. ; transgenic plant
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Transgenic potato plants of cv. Désirée carrying an antibacterial gene, coding for a cecropin lytic peptide analogue, were inoculated with a virulent strain ofPseudomonas solanacearum under controlled conditions. The disease index scored during three repeated infection trials indicated an increased variability in plant response among the transgenic lines which gave either a more susceptible or a more resistant response to the pathogen when compared with untransformed Désirée. Immunity toP. solanacearum was not observed, but it was possible to select a group of transgenic lines that showed resistance levels and disease development curves comparable to the field resistant cv. Cruza 148.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02357742
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  • 48
    Digitale Medien
    Digitale Medien
    Rapid micropreps and minipreps of Ti plasmids and binary vectors fromAgrobacterium tumefaciens (1995)
    Springer
    Transgenic research 4 (1995), S. 349-351 
    Details
    ISSN: 1573-9368
    Schlagwort(e): Agrobacterium ; Ti plasmid ; binary vector ; minipreparation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A simple and versatile procedure has been developed for the isolation of both large helper/Ti plasmids and binary vectors fromAgrobacterium tumefaciens. Using a slightly modified alkaline lysis protocol, intact plasmid can be recovered from cultures grown in standard micro-centrifuge tubes or culture tubes in sufficient yield and purity to allow for restriction analysis on ethidium bromide stained gels of the 〉200 kb Ti plasmid DNA. Contamination by chromosomal DNA is minimal and there is thus no need for isopycnic gradient purification. This same procedure can be combined with a high temperature treatment (37°C) and antibiotic selection to generate preparations containing binary vector DNA that are virtually free of interfering Ti plasmid DNA. Restriction patterns produced from these binary vector DNA preparations are unambiguous and therefore preliminary screening by Southern hybridization can be eliminated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01972532
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  • 49
    Digitale Medien
    Digitale Medien
    Cell competence forAgrobacterium-mediated DNA transfer inPisum sativum L. (1995)
    Springer
    Transgenic research 4 (1995), S. 184-191 
    Details
    ISSN: 1573-9368
    Schlagwort(e): competence ; transient ; transformation ; Agrobacterium ; grain legume ; histochemical GUS-detection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Distribution and properties of pea (Pisum sativum L.) cells, competent forAgrobacterium-mediated transformation were analysed byin situ histochemical detection of GUS (β-glucuronidase) activity, 4 d after inoculation with engineeredAgrobacterium tumefaciens. The vector system consisted of the hypervirulent disarmed strain EHA101 and the binary plasmid pIBGUS, carrying an intron-containing, 35S-promotor drivengusA (oruidA) gene and two selectable marker genes. Cells competent for transformation were mainly restricted to the dedifferentiating cells neighbouring the vascular system of cotyledon and epicotyl explants. A standardized assay was developed, allowing determination and quantification of factors influencing number and distribution of competent cells. In etiolated seedlings, competence for transformation decreased with the distance of the epicotyl explant from the shoot apex and was specifically induced by the exogenous application of auxins. Transient expression ofgusA afterAgrobacterium-mediated DNA transfer was dramatically reduced upon application of cell-cycle and DNA replication inhibitors aphidicolin, colchicine and nalidixic acid. GUS expression after direct DNA transfer of double-stranded plasmid DNA (via PEG into protoplasts or via particle bombardment of epicotyl segments) was independent of cell-division/DNA replication. A GUS-positive mutant of EHA101 was constructed to allowin situ analysis of attaching bacteria within the plant tissue. Attachment and invasion was inhibited by well-developed cuticula but was restored after chloroform treatment of the tissue surface. Moreover, no correlation was found between distribution of attaching bacteria and the pattern of transformation-competent cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01968783
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  • 50
    Digitale Medien
    Digitale Medien
    Ti plasmid-encoded octopine and nopaline catabolism in Agrobacterium: specificities of the LysR-type regulators OccR and NocR, and protein-induced DNA bending (1995)
    Springer
    Molecular genetics and genomics 249 (1995), S. 102-110 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Ti plasmid ; Activator ; Opines ; LysR family
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The occ and noc regions in octopine and nopaline Ti plasmids, respectively, are responsible for the catabolism of octopine and nopaline in Agrobacterium. The functions are activated in the presence of the opines by OccR and NocR, two related regulatory proteins, and the promoters contain common sequence motifs. We have investigated heterologous interactions between the regulators and the promoters. Previous experiments using all possible heterologous combinations of opines, regulators, and promoters in vivo had demonstrated that only the combination of nopalme, NocR, and the occ promoter led to limited promoter activation. We now show that OccR and NocR bind to the heterologous promoters in vitro and in vivo. The weak or non-existent promoter activation actually observed could be explained by the assumption that OccR and NocR use different activation mechanisms; we investigated protein-induced DNA bending because of reports that the two regulators differ in this respect. Analysis with a bending vector showed that both OccR and NocR induced a DNA bend that is relaxed in the presence of the respective opine. The data suggest that subtle differences in regulator/promoter interactions are responsible for the inactivity of the heterologous combinations. Investigations with a chimeric NocR/OccR protein indicated that it induced a DNA bend in both promoters. No opine-induced relaxation was detectable with the hybrid, and the inducible promoter was not activated. These findings suggest that bend relaxation may be an integral part of promoter activation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00290241
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  • 51
    Digitale Medien
    Digitale Medien
    New plant promoter and enhancer testing vectors (1995)
    Springer
    Molecular breeding 1 (1995), S. 419-423 
    Details
    ISSN: 1572-9788
    Schlagwort(e): binary vectors ; gus ; T-DNA ; Agrobacterium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract We describe here a set of binary vectors suitable forAgrobacterium-mediated gene transfer and specially designed for studying plant promoters. These vectors are based on the use of thegus reporter gene, contain multiple unique restriction sites upstream of thegus gene, and minimal promoters for testing the effect of enhancers or activator elements. In addition, an intron-containinggus (uidA) gene was introduced into one of these vectors in order to examine reporter gene activity in tissues whereAgrobacterium contamination may be a problem or in transient expression assays.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01248419
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  • 52
    Digitale Medien
    Digitale Medien
    Efficient transformation and regeneration of carnation cultivars usingAgrobacterium (1995)
    Springer
    Molecular breeding 1 (1995), S. 283-293 
    Details
    ISSN: 1572-9788
    Schlagwort(e): Agrobacterium ; carnation ; Dianthus caryophyllus ; regeneration ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract We have developed an efficient method for transformation and regeneration of plants from carnation,Dianthus caryophyllus L. Whole leaves fromin vitro shoot cultures were mixed withAgrobacterium, cocultivated for 5 days and then plated on 2 µg/l chlorsulfuron (CS). Regenerated shoots and shoot clusters were divided into smaller sections and plated on 3 µg/l CS for selection to produce fully transformed shoots. Geneticin (G418) and kanamycin used were not as effective selective agents as CS. All regenerated shoots were vitrified. These were normalized, rooted and transferred to the greenhouse. 100% of regenerated plants were transformed based on rooting assay, GUS assay, PCR and Southern analysis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02277428
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  • 53
    Digitale Medien
    Digitale Medien
    Isolation and functional analysis of a set of auxin genes with low root-inducing activity from an Agrobacterium tumefaciens biotype III strain (1989)
    Springer
    Plant molecular biology 12 (1989), S. 271-283 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; auxins ; roots ; oncogenes ; grapevine ; iaa genes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A new type of root-inducing iaa gene set was cloned from the Ti plasmid of the biotype III Agrobacterium tumefaciens strain Tm-4. These iaa genes are characterized by a very low DNA homology with the well-characterized iaa gene set, iaaM and iaaH, of the “common DNA” region of the biotype I strain Ach5 and by a low root-inducing activity. The biological activities of both iaa gene sets were compared by transferring each into a disarmed Ti vector and by testing the resulting strains on Nicotiana rustica leaf discs, decapitated Datura stramonium stems, tomato plants and Kalanchoë daigremontiana. Tm-4 iaa genes have a reproducibly weaker root-inducing ability on Nicotiana rustica, induce very little tumour growth on decapitated Datura plants or on tomato plants and do not induce roots on Kalanchoë daigremontiana. The Tm-4 iaa region was mapped by λ:: Tn5 transposon mutagenesis and tested on Nicotiana rustica. These tests combined with complementation experiments map the iaa genes to a 4.5-kb region. The Tm-4 iaa genes were able to complement the corresponding Ach5 iaa genes on Nicotiana rustica, indicating that the differences between these genes are quantitative rather than qualitative. Complementation experiments on Kalanchoë showed the iaaM gene of Tm-4 responsible for the overall weak auxin activity of the intact iaa set. In view of the observed structural and functional differences we propose to call the Tm-4 iaa genes TB-iaaM and TB-iaaH and the Ach5 iaa genes A-iaaM and A-iaaH.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00043204
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  • 54
    Digitale Medien
    Digitale Medien
    Specificity of Agrobacterium-mediated delivery of maize streak virus DNA to members of the Gramineae (1989)
    Springer
    Plant molecular biology 12 (1989), S. 31-40 
    Details
    ISSN: 1573-5028
    Schlagwort(e): agroinfection ; Agrobacterium ; strains ; maize streak virus ; Gramineae ; maize
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Parameters affecting the efficiency of agroinfection of maize streak virus (MSV) in maize have been determined. Monomeric units, cloned at a number of sites in the MSV genome were not infectious but multimeric units containing partial duplications were equally as infectious as complete tandem dimeric clones. Inoculation of tandem dimeric units conjugated into different strains of Agrobacterium showed that both A. tumefaciens and A. rhizogenes were able to transfer DNA to maize and this ability was Ti (or Ri) plasmid-specific. Nopaline strains of A. tumefaciens and both agropine and mannopine A. rhizogenes strains efficiently transferred MSV DNA to maize. A number of strains were capable of MSV DNA transfer to other members of the Gramineae, providing information which may be essential for Agrobacterium-mediated transformation of monocotyledonous plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00017445
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  • 55
    Digitale Medien
    Digitale Medien
    Transformation of plant cells via Agrobacterium (1989)
    Springer
    Plant molecular biology 13 (1989), S. 327-336 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; plant cell transformation ; plant tumor induction ; plant vector systems
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00025321
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  • 56
    Digitale Medien
    Digitale Medien
    Induction and growth properties of carrot roots with different complements of Agrobacterium rhizogenes T-DNA (1989)
    Springer
    Plant molecular biology 13 (1989), S. 43-52 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; hairy roots ; T-DNA ; geotropism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Single and multiple infections of carrot discs were carried out with Agrobacterium strains harbouring different segments of pRi1855 TL-DNA cloned in the binary vector Bin 19 and with a strain carrying the TR-DNA from the same Ri plasmid. Roots induced by the various co-inoculations were cultured and their growth patterns were followed. Abundant roots could be induced by TL-DNA rol genes A, B and C as a single insert (rolA+B+C) and by rolB alone provided an extended segment beyond its 5′ noncoding region was included in the construction. A depression of rooting capability was caused by the inclusion of rolC together with rolB (rolB+C). In all cases co-inoculation with the Agrobacterium carrying TR-DNA-borne auxin genes was necessary for root induction since none of the rol constructions was in itself capable of eliciting any response; an exceeding majority of these roots were however shown to contain rol genes but no TR-DNA. Rooting was also elicited if rol constructions were co-inoculated with a strain carrying TL-DNA genes 13 and 14 (ORF13+14) instead of the TR-DNA strain. These roots were shown to contain both rol genes and ORF13+14. Striking differences in growth properties were shown by roots containing different complements of TL-DNA genes. Typical hairy root traits, high growth rate, branching and, most noticeably, absence of geotropism, were shown by roots containing rolB alone, while roots with rolA+B+C were geotropic as normal carrot roots. Hairy root traits were conferred to rolA+B+C roots by the concomitant presence of ORF13+14 and by the addition of auxin to the culture medium. A model is presented which attempts to rationalize the growth patterns by assigning interplaying roles to the various TL-DNA genes involved.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00027334
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  • 57
    Digitale Medien
    Digitale Medien
    Phleomycin resistance as a dominant selectable marker for plant cell transformation (1989)
    Springer
    Plant molecular biology 13 (1989), S. 365-373 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; binary vectors ; bleomycin ; phleomycin ; selective markers ; tobacco
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Tobacco cells are sensitive to bleomycin and phleomycin. The Tn5 and the Streptoalloteichus hindustanus (Sh) bleomycin resistance (‘Ble’) genes conferring resistance to these antibiotics have each been inserted into two plant expression vectors. They are flanked by the nopaline synthase (nos) or the cauliflower mosaic virus (CaMV) 35S promoters on one side, and by the nos polyadenylation signal on the other. These four chimaeric genes were introduced into the binary transformation vector pGA 492, which were thereafter mobilized into Agrobacterium tumefaciens strain LBA 4404. The resulting strains were used to transform Nicotiana tabacum cv. Xanthi nc using the leaf disc transformation procedure. In all cases, phleomycin- and bleomycin-resistant tobacco plants were regenerated from transformed cells under selective conditions; however the highest frequency of rooted plants was obtained when transformation was carried out with the ‘Sh Ble’ gene under the control of the 35S promoter. Phleomycin resistance was stably transmitted to sexual offspring as a dominant nuclear trait as confirmed by Southern blotting.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00015548
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  • 58
    Digitale Medien
    Digitale Medien
    Thiophene accumulation in relation to morphology in roots of Tagetes patula (1989)
    Springer
    Planta 179 (1989), S. 43-50 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Auxin and thiophene in roots ; Root culture ; Root morphology ; Tagetes ; Thiophene ; Transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Roots of marigold (Tagetes patula L.) accumulate thiophenes, heterocyclic sulfurous compounds with strong biocidal activity. In detached roots cultured in vitro, the thiophene content was 5 μmol·(g fresh weight)-1 which is 25-times higher than in roots attached to the plant. In roots derived from tissues transformed by Agrobacterium tumefaciens and A. rhizogenes, the morphology and thiophene content varied with the bacterial strain used. Transformation stimulated the elongation of the root tips and the formation of lateral roots but lowered the thiophene level to 20–50% relative to the concentration in untransformed detached roots. A negative correlation was found between the number of laterals in a root system and the thiophene content. Extensive branching and a decrease in thiophene accumulation was evoked in untransformed roots by indole-3-acetic acid (1–10 μmol·l-1) added to the medium. Within the roots, the highest thiophene concentrations were found in the tips. The results indicate that auxin directly or indirectly plays a role in the regulation of the thiophene level in root tips.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00395769
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  • 59
    Digitale Medien
    Digitale Medien
    Carrot (Daucus carota) hypocotyl transformation usingAgrobacterium tumefaciens (1989)
    Springer
    Plant cell reports 8 (1989), S. 354-357 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Agrobacterium ; Somatic Embryogenesis ; Electroporation ; β-Glucuronidase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Daucus carota hypocotyl sections were transformed withAgrobacterium tumefaciens LBA4404 containing CaMV 35S promoter, β-glucuronidase coding sequence and the nopaline synthase (Nos) poly adenylation sequences in Bin 19. Sliced sterile seedling hypocotyl segments were preincubated for 2 days, co-cultivated withAgrobacterium for an additional 2 days, and then transferred to medium containing 100ug/ml of kanamycin and 400ug/ml carbenicillin. In 6 weeks kanamycin resistant calli were obtained in 5.8% of the explants from one variety. Calli were subcultured on solid medium, and in 4 weeks introduced into suspension culture. NPTII and Southern blot analysis confirmed that three selected lines were transformed with 1–3 copies of the GUSII construction. GUS activity in transformants was 5 to 250 fold over background.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00716672
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  • 60
    Digitale Medien
    Digitale Medien
    Upstream non-coding region which confers polar expression to Ri plasmid root inducing gene rolB (1989)
    Springer
    Molecular genetics and genomics 216 (1989), S. 239-244 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Hairy root ; T-DNA ; Glucuronidase gene
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Root differentiation could be elicited on carrot discs by transformation with the agropine Ri plasmid rolB gene cloned in the binary vector Bin19, provided two conditions were met. Firstly, an adequate auxin supply had to be provided. This was achieved by co-inoculation with a strain carrying only the auxin synthetic genes of the TR-DNA. Most of the resulting roots were then shown to harbour only rolB and no aux genes. Secondly, an extended non-coding region (∼1200 bp) at the 5′ end of rolB had to be included in the construction. A shorter (∼300 bp) 5′ region, including TATA and CCAAT boxes, was not sufficient to trigger root differentiation. Both the extended (B1185) and reduced (B310) 5′ regions of rolB were then cloned upstream of the β-glucuronidase (GUS) reporter gene and infections carried out both on the apical and on the basal side of carrot discs. Strong expression of GUS, visualized histochemically as an intense blue colouring of transformed cells was observed with B1185-GUS constructions on the apical side of the discs. Only occasionally could coloured cells be observed on the basal side of the discs with B1185-GUS and on both apical and basal sides with B310-GUS constructions. Strong GUS expression was, on the contrary, achieved on cells of both auxin-rich (apical) and auxin-depleted (basal) sides of the discs with the strong constitutive viral promoter, CaMV35S. These results indicate the presence of an upstream regulatory region which confers polar expression to the rolB gene and suggest a role for auxin in its activation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00334362
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  • 61
    Digitale Medien
    Digitale Medien
    Transformation of meristematic cells in the shoot apex of cultured pea shoots byAgrobacterium tumefaciens andA. rhizogenes (1989)
    Springer
    Protoplasma 148 (1989), S. 101-105 
    Details
    ISSN: 1615-6102
    Schlagwort(e): In vitro shoots ; Pisum sativum ; Meristematic cells ; Shoot apices ; Transformation ; Agrobacterium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Different tissues in cultured pea shoots were inoculated withAgrobacterium tumefaciens wild types C 58 and ACH 5 andA. rhizogenes wild type 9402. The C 58 and 9402 bacteria induced the formation of tumours and hairy roots respectively while the ACH 5 was inactive. The younger the tissue the more rapidly it responded to the active bacteria. The shoot apex was the most reactive organ and developed into a tumour, theA. rhizogenes tumours subsequently giving rise to transformed hairy roots. Histological examination showed that transformed cells (including those within the apical dome) initially became highly vacuolate before dividing rapidly to form a tumour. These changes were accompanied by cell division in surrounding tissues.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02079328
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  • 62
    Digitale Medien
    Digitale Medien
    Agrobacterium tumefaciens 6bgenes are strain-specific and affect the activity of auxin as well as cytokinin genes (1989)
    Springer
    Molecular genetics and genomics 219 (1989), S. 217-224 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; 6b gene ; Agrobacterium host range ; Oncogenes ; Plant growth regulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The T-region located 6b gene of Agrobacterium tumefaciens has been found to interfere with cytokinin effects produced by the cotransferred ipt gene. We have compared the biological activity of three different 6b genes: A-6b from Ach5 (octopine, biotype 1), C-6b from C58 (nopaline, biotype 1) and T-6b from Tm4 (octopine, biotype III) by using different biological assays. Each 6b gene was inserted into a disarmed vector and tested on tobacco stems in coinfection experiments with the Ach5 cytokinin (ipt) gene (A-ipt). A-ipt/C-6b coinfections produced tumours with shoots, A-ipt/A-6b coinfections green tumours and A-ipt/T-6b coinfections tumours with a necrotic surface. The tumour phenotypes obtained were independent of the 6b/A-ipt coinfection ratios, indicating that the strain-specific 6b effects result from the activity of a non-diffusible 6b encoded product. Studies with ipt-less Tm4 mutants showed that 6b genes affect other tumour genes besides the ipt gene and pointed to an influence of T-6b on auxin effects resulting from the Tm4 iaa system. T-iaa/T-6b coinfection experiments showed that T-6b did indeed strongly increase tumour formation by the Tm4 iaa genes. The three 6b genes also have effects which do not require other T-region genes. The complex role of the 6b gene in crown gall induction and Agrobacterium host range will be discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00261180
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  • 63
    Digitale Medien
    Digitale Medien
    Single-stranded DNA transforms plant protoplasts (1989)
    Springer
    Molecular genetics and genomics 220 (1989), S. 65-68 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Transformation ; Single-stranded DNA ; Agrobacterium ; Transient expression ; Extrachromosomal
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The transfer of the Agrobacterium T-DNA to plant cells involves the induction of the Ti plasmid virulence genes. This induction results in the generation of linear single-stranded (ss) copies of the T-DNA inside Agrobacterium and such molecules might be directly transferred to the plant cell. A central requirement of this ss transfer model is that the plant cell must generate a second strand and integrate the resulting double-stranded (ds) molecule into its genome. Here we report that incubating plant protoplasts with ss or ds DNA under conditions favouring DNA uptake results in transformation. The frequencies of transformation are similar and analysis of ss transformants suggests that the introduced DNA becomes double stranded and integrated. Analysis of transient expression from introduced ss DNA suggests that generation of the second strand is rapid and extrachromosomal.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00260857
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  • 64
    Digitale Medien
    Digitale Medien
    Distribution of two Agrobacterium tumefaciens insertion elements in natural isolates: Evidence for stable association between Ti plasmids and their bacterial hosts (1989)
    Springer
    Molecular genetics and genomics 219 (1989), S. 145-152 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; IS elements ; Ti plasmid ; T-region ; Bacterial evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A large number of Agrobacterium tumefaciens strains of the biotype III group carry two to ten copies of two related IS elements, IS866 and IS867. A study of the distribution and localization of these elements in 54 strains showed that one IS866 and two IS867 copies are always found at characteristic sites on the octopine/cucumopine and vitopine Ti plasmids, whereas varying amounts of IS866 and IS867 copies occur at different positions on the chromosome. By comparison of the IS patterns, an evolutionary tree could be deduced which shows the phylogenetic relationships between 23 different types of Agrobacterium strains. The structures of the T-regions of the different strains were also compared. Within the octopine/cucumopine group, eight T-region patterns could be defined. These patterns were found to be correlated with the chromosomal IS patterns. This strongly suggests that the IS866 and IS867 containing Ti plasmids are stably associated with their bacterial hosts. The possible role of the IS866 and IS867 elements in Ti plasmid evolution is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00261170
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  • 65
    Digitale Medien
    Digitale Medien
    Agrobacterium-mediated transformation of somatic embryos as a method for the production of transgenic plants (1989)
    Springer
    Methods in cell science 12 (1989), S. 145-150 
    Details
    ISSN: 1573-0603
    Schlagwort(e): Agrobacterium ; gene transfer ; somatic embryos ; walnut ; β-glucuronidase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Somatic embryos have been successfully used as a target tissue for transformation and regeneration of transgenic walnut plants. Walnut somatic embryos, initiated originally from developing zygotic embryos, proliferate numerous secondary embryos from single cells in the epidermal layer. These single cells in intact somatic embryos are susceptible to transformation by genetically engineeredAgrobacterium tumefaciens and provide a means to regenerate nonchimeric transgenic plants. This gene transfer system has been made more efficient using, a) vector plasmids containing two marker genes encoding β-glucuronidase (GUS) and aminoglycoside phosphotransferase (APH(3′)II) and B) a more virulent strain ofAgrobacterium. This system should be applicable to any crop that undergoes repetitive embryogenesis from singleAgrobacterium-susceptible cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01404441
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  • 66
    Digitale Medien
    Digitale Medien
    Mass-spectrometric quantitation of cytokinins in tobacco crown-gall tumours induced by mutated octopine Ti plasmids of Agrobacterium tumefaciens (1988)
    Springer
    Planta 176 (1988), S. 230-234 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Auxin in tumors ; Cytokinin (in tumors, turnover, oxidase) ; Mutant (T-DNA) ; Nicotiana (crown gall) ; T-DNA mutants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The levels of the major cytokinins, zeatin, zeatin riboside, zeatin riboside-5′-monophosphate and zeatin-7-glucoside were measured in tobacco (Nicotiana tabacum L.) crown-gall tissues carrying insertion and deletion mutations in the T-DNA. Measurements were made by combined gas chromatography-mass spectrometry using selected ion monitoring with 15N- and 2H-labelled internal standards. The results demonstrate that, relative to wild-type tumour tissue, cytokinin levels are considerably elevated in tissues lacking functional T-DNA auxin-biosynthetic genes. From a detailed analysis of the major cytokinin metabolites it is concluded that a reduction in the extent of cytokinin degradation via N6-side-chain cleavage is an important factor leading to increased cytokinin levels in these tissues.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00392449
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  • 67
    Digitale Medien
    Digitale Medien
    Tissue-specific expression of a pea legumin gene in seeds of Nicotiana plumbaginifolia (1988)
    Springer
    Plant molecular biology 10 (1988), S. 203-214 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; gene expression ; legumin (Pisum) ; Nicotiana ; seed storage protein ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A 3.4-kilobase genomic DNA fragment from Pisum sativum L. containing the LegA gene, which encodes a major legumin storage protein, was transferred to Nicotiana plumbaginifolia using an Agrobacterium tumefaciens strain containing the Bin 19 binary vector system. Northern hybridisation analysis of legA-transformed plants demonstrated that legumin-specific RNA was present in developing seeds but not in developing leaves. Legumin protein was immunologically detected in the mature seeds of legA-transformed plants, and was present as the correct-size protein composed of disulphide-bonded polypeptides. It is concluded that the transferred pea genomic fragment contains all the information necessary for seed-specific expression of the legA gene, and for correct processing of the primary transcript and the precursor legumin protein.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00027397
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  • 68
    Digitale Medien
    Digitale Medien
    Agrobacterium-mediated inoculation of plants with tomato golden mosaic virus DNAs (1988)
    Springer
    Plant molecular biology 10 (1988), S. 225-234 
    Details
    ISSN: 1573-5028
    Schlagwort(e): geminivirus ; Agrobacterium ; tomato golden mosaic virus ; agroinoculation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have adapted the “agroinfection” procedure of Grimsley and co-workers [4,5] to develop a simple, efficient, reproducible infectivity assay for the insect-transmitted, split-genome geminivirus, tomato golden mosaic virus (TGMV). Agrobacterium T-DNA vectors provide efficient delivery of both components of TGMV when used in mixed inoculation of wild-type host plants. A greater increase in infection efficiency can be obtained by Agrobacterium delivery of the TGMV A component to “permissive” transgenic plants. These “permissive” plants contain multiple tandem copies of the B component integrated into the host genome. An inoculum containing as few as 2000 Agrobacterium cells can produce 100% infection under these conditions. Further, our results show that there is a marked effect of the configuration of the TGMV A components within the T-DNA vector on time of symptom development. We have also found that transgenic plants carrying tandem copies of the A component do not complement the B component. Possible mechanisms to explain these results and the potential use of this system to further study the functions of the geminivirus components in infection are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00027399
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  • 69
    Digitale Medien
    Digitale Medien
    Enhanced nodule initiation on alfalfa by wild-typeRhizobium meliloti co-inoculated withnod gene mutants and other bacteria (1988)
    Springer
    Planta 174 (1988), S. 385-395 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Co-inoculation ; Medicago ; Mutant (Rhizobium) ; Nodulation ; Rhizobium ; Root nodule initiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Nodule formation on alfalfa (Medicago sativa L.) roots was determined at different inoculum dosages for wild-typeRhizobium meliloti strain RCR2011 and for various mutant derivatives with altered nodulation behavior. The number of nodules formed on the whole length of the primary roots was essentially constant regardless of initial inoculum dosage or subsequent bacterial multiplication, indicative of homeostatic regulation of total nodule number. In contrast, the number of nodules formed in just the initially susceptible region of these roots was sigmoidally dependent on the number of wild-type bacteria added, increasing rapidly at dosages above 5·103 bacteria/plant. This behavior indicates the possible existence of a threshold barrier to nodule initiation in the host which the bacteria must overcome. When low dosages of the parent (103 cells/plant) were co-inoculated with 106 cells/plant of mutants lacking functionalnodA, nodC, nodE, nodF ornodH genes, nodule initiation was increased 10- to 30-fold. Analysis of nodule occupancy indicated that these mutants were able to help the parent (wild-type) strain initiate nodules without themselves occupying the nodules. Co-inoculation withR. trifolii orAgrobacterium tumefaciens cured of its Ti plasmid also markedly stimulated nodule initiation by theR. meliloti parent strain. Introduction of a segment of the symbiotic megaplasmid fromR. meliloti intoA. tumefaciens abolished this stimulation.Bradyrhizobium japonicum and a chromosomal Tn5 nod- mutant ofR. meliloti did not significantly stimulate nodule initiation when co-inoculated with wild-typeR. meliloti. These results indicate that certainnod gene mutants and members of theRhizobiaceae may produce extracellular “signals” that supplement the ability of wild-typeR. meliloti cells to induce crucial responses in the host.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00959525
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  • 70
    Digitale Medien
    Digitale Medien
    Genotype-independent leaf disc transformation of potato (Solanum tuberosum) using Agrobacterium tumefaciens (1988)
    Springer
    Theoretical and applied genetics 76 (1988), S. 767-774 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Solanum tuberosum ; Transformation ; Agrobacterium ; Ethylene ; Phosphinotricin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Leaves of the in vitro grown potato cultivars ‘Bintje’, ‘Berolina’, ‘Desiree’, and ‘Russet Burbank’ were wounded and co-cultivated with Agrobacterium strains having chimeric bar and nptII genes on a disarmed T-DNA. Each leaf from these cultivars formed numerous calli on kanamycin-containing medium, and almost all calli regenerated shoots. For ‘Russet Burbank’, it was necessary to include AgNO3 in the medium to obtain efficient shoot regeneration. The transformed plants have one to a few copies of the T-DNA, show NPT-II and PAT activities, and are resistant to high doses of the commercial preparation of phospinotricin (glufosinate). Almost no somaclonal variation was detected in trans-genic plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00303524
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  • 71
    Digitale Medien
    Digitale Medien
    Expression of bacterial chitinase protein in tobacco leaves using two photosynthetic gene promoters (1988)
    Springer
    Molecular genetics and genomics 212 (1988), S. 536-542 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Small subunit of ribulose bisphosphate carboxylase ; Chlorophyll a/b binding protein ; Promoter comparisons ; Chitinase activity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A bacterial chitinase gene from Serratia marcescens (chiA) was fused to (i) a promoter of the ribulose bisphosphate carboxylase small subunit (rbcS) gene and (ii) two different chlorophyll a/b binding protein (cab) gene promoters from petunia. The resulting constructions were introduced into Agrobacterium Ti plasmid-based plant cell transformation vectors and used to generate multiple independent transgenic tobacco plants. ChiA mRNA and protein levels were measured in these plants. On average, the rbcS/chiA fusion gave rise to threefold more chiA mRNA than either cab/chiA fusion. We investigated the influence of sequences around the translational initiation ATG codon on the level of ChiA protein. The rbcS/chiA and cab/chiA fusions in which the sequence in the vicinity of the translational initiation codon is ACC ATGGC gave rise to transformants with higher levels of ChiA protein than those carrying a cab/chiA fusion with the sequence CAT ATGCG in the same region. This difference in translational efficiency is consistent with previous findings on preferred sequences in this region of the mRNA. In those transformants showing the highest level of ChiA expression, ChiA protein accumulated to about 0.25% of total soluble leaf protein. These plants contained significantly higher chitinase enzymatic activity than control plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00330861
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  • 72
    Digitale Medien
    Digitale Medien
    Relative strengths of the 35S califlower mosaic virus, 1′, 2′, and nopaline synthase promoters in transformed tobacco sugarbeet and oilseed rape callus tissue (1988)
    Springer
    Molecular genetics and genomics 212 (1988), S. 182-190 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Promoter strength ; Transformed callus ; Chitinase gene ; Octopine synthase gene ; Agrobacterium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The 35S promoter of cauliflower mosaic virus and promoters from the nopaline synthase, 1′ and 2′ genes of Agrobacterium tumefaciens T-DNA were fused to the bacterial octopine synthase and chitinase gene coding regions. These chimaeric gene constructions were introduced into tobacco, sugarbeet and oilseed rape cells and their relative levels of expression measured by primer extension analysis of RNA isolated from pooled populations of stably transformed calli. In tobacco callus, the 35S promoter provided the highest levels of gene expression, followed by the 2′, 1′ and nopaline synthase promoters. While the ranking of these promoters is conserved in sugarbeet and oilseed rape callus, there is between-species variation in the relative strength of these promoters. In all three species, transcription initiation is conserved for each of the chimaeric gene constructions. Additional constructions in which the 5′ untranslated leader of a petunia chlorophyll a/b binding protein gene is substituted for DNA downstream of the 35S transcription start site demonstrates that heterologous 5′ leader sequences can be utilized to augment steady-state levels of reporter gene expression
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00322463
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  • 73
    Digitale Medien
    Digitale Medien
    Construction of a Tra− deletion mutant of pAgK84 to safeguard the biological control of crown gall (1988)
    Springer
    Molecular genetics and genomics 212 (1988), S. 207-214 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Crown gall ; Biological control ; Agrocin 84 ; Agrocin plasmid transfer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Agrobacterium radiobacter strain K84 is used commercially for the biological control of crown gall. It contains the conjugative plasmid pAgK84, which encodes the synthesis of agrocin 84, an antibiotic that inhibits many pathogenic agrobacteria. A breakdown of control is threatened by the transfer of pAgK84 to pathogens, which then become resistant to agrocin 84. A mutant of pAgK84 with a 5.9-kb deletion overlapping the transfer (Tra) region was constructed using recombinant DNA techniques. The BamHI fragment B1 which covers most of the Tra region was cloned in pBR325 and its internal EcoRI fragments D1 and H, which overlap the Tra region, were removed, leaving 3.7 kb and 0.5 kb of pAgK84 on either side of the deletion. The latter was increased to 3.3 kb by adding EcoRI fragment D2 from a BamHI fragment C clone. The modified pBR325 clone was mobilized into Agrobacterium strain NT1 harbouring pAgK84 with a Tn5 insertion just outside the Tra region but covered by the deletion. A Tra+ cointegrate was formed between the Tn5-insertion derivative and the pBR325-based deletion construct by homologous recombination. The cointegrate was transferred by conjugation to a derivative of strain K84 lacking pAgK84, in which a second recombination event generated a stable deletion-mutant by deletion-marker exchange. The resultant new strain of A. radiobacter, designated K1026, shows normal agrocin 84 production. Mating experiments show that the mutant plasmid, designated pAgK1026, is incapable of conjugal transfer at a detectable frequency.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00334686
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  • 74
    Digitale Medien
    Digitale Medien
    Rhizobium phaseoli: A molecular genetics view (1988)
    Springer
    Plant and soil 108 (1988), S. 179-184 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Agrobacterium ; genomic rearrangements ; molecular genetics ; Rhizobium ; strains instability ; symbiosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract We have used molecular genetics techniques to analyze the structural and functional organization of genetic information ofRhizobium phaseoli, the symbiont of the common bean plantPhaseolus vulgaris. As in otherRhizobium species, the genome consists of the chromosome and plasmids of high molecular weight. Symbiotic determinants, nitrogen fixation genes as well as nodulation genes, are localized on a single replicon, the symbiotic (sym) plasmid. Thesym plasmid of differentR. phaseoli strains was transferred to anAgrobacterium tumefaciens strain cured of its native plasmids. In all cases, Agrobacterium transconjugants able to nodulate bean plants were obtained. Some of the transconjugants had the capacity to elicit an effective symbiosis. The genome ofR. phaseoli is complex, containing a large amount of reiterated DNA sequences. In mostR. pahseoli strains one of such reiterated DNA families corresponds to the nitrogenase structural genes (nif genes). A functional analysis of these genes suggested that the presence of reiteratednif genesis is related to the capacity of fixing atmospheric nitrogen in the symbiotic state. The presence of several repeated sequences in the genome might provide sites for recombination, resulting in genomic rearrangements. By analyzing direct descendants of a single cell in the laboratory, evidence of frequent genomic rearrangements inR. phaseoli was found. We propose that genomic rearrangements constitute the molecular basis of the frequent variability and loss of symbiotic properties in different Rhizobium strains.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02370113
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  • 75
    Digitale Medien
    Digitale Medien
    Structure, organization and expression of transferred DNA in Nicotiana plumbaginifolia crown-gall tissues (1987)
    Springer
    Planta 171 (1987), S. 393-405 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Crown-gall ; DNA, transferred ; Nicotiana (T-DNA) ; T-DNA structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Data are provided which show that transferred DNA (T-DNA) present in Nicotiana plumbaginifolia crown-gall lines in most cases was scrambled and not intact. Both wild-type, and ‘rooter’- and ‘shooter’-type mutants of octopine-type Agrobacterium tumefaciens were used to infect N. plumbaginifolia plantlets, cultured in vitro. Resulting tumors were excised from the plantlets and cultured for more than three years. During subculturing the tumor lines were scored for the following phenotypic traits: phytohormone autonomous growth in vitro (Aut+), spontaneous shoot regeneration (Reg+), root deficiency of shoots (Rod+), octopine production (Ocs+) and mannopine and agropine production (Mas+Ags+). An unexpectedly large variety of phenotypes was observed. For instance, two out of three tumor lines induced on haploid plantlets by the rooter mutant LBA4210 regenerated shoots, a phenomenon which is not observed for octopine tobacco tumor lines. Fifty percent of the crown-gall lines studied did not contain octopine. Only one line out of six independent lines analyzed was found to have a ‘regular’ T-DNA structure. Occurrence of aberrant T-DNA structures was not correlated with the ploidy level of infected plantlets, nor with the T-region structure of the inciting bacterial strain. The pattern of TL-DNA transcripts was studied for one line and correlated well with the aberrant T-DNA structure detected. Segments of TR-DNA, having irregular structures as well, were detected in two out of the six lines studied. The scrambled nature of the TR-DNA explained the absence of mannopine and agropine in these two lines. In addition, it was observed that N. plumbaginifolia tissue lines which did not carry T-DNA, became readily phytohormone autotrophic (habituated) at an early stage in tissue culture.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00398685
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  • 76
    Digitale Medien
    Digitale Medien
    Stability and expression of transferred DNA in F1 tobacco transformants studied at various states of differentiation (1987)
    Springer
    Planta 172 (1987), S. 448-462 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Crown gall ; Nicotiana (crown gall, T-DNA) ; Transformation (tobacco) ; Transferred DNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Grafts from the SR1 tobacco crown-gall lines NT1 (having a deletion eliminating part of the transferred (TL)-DNA auxin locus) and NT2 (having an IS60 insertion in gene 2 of this auxin locus) were cross-pollinated with pollen from nontransformed SR1 tobacco plants. One half of the resulting F1 progeny resembled the female parent (“transformed” NT1-like and NT2-like seedlings respectively) and one half resembled the male parent (“non-transformed” SR1-like seedlings). For three states of differentiation (callus, shoot, graft) all phenotypic markers of the transformed seedlings studied were identical to those of the transformed female parent. Most phenotypic markers of non-transformed seedlings corresponded with markers of the male parent. Unlike the SR1 male parent, however, the SR1-like seedlings showed the maternal traits hyperstyly and male sterility. These two traits were inherited by 100% of the F1 seedlings studied. Ninety percent of the non-transformed F2 seedlings were still male-sterile whereas in as much as 50–100% of the non-transformed F3 progeny, male fertility had been restored. The SR1-like F1 seedlings did not contain any T-DNA. At the level of restriction-fragment analysis the T-DNA structures of all 22 NT1-like seedlings examined were identical to the T-DNA structure of their female parent NT1. The steady-state level of transcripts 4 (cytokinin locus) and 6a/6b relative to transcript 3 (octopine-synthase locus) was less in shoots and grafts than in callus. Observed variation in shoot morphology among the twenty-two NT1-like seedlings was not correlated with T-DNA structure, organization and expression at the level of steady-state mRNA. The T-DNA structure of NT2 and its transformed seedlings deviated from regular border-to-border TL-DNA, in that it extended beyond the left border repeat.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00393860
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  • 77
    Digitale Medien
    Digitale Medien
    Initiation of auxin autonomy in Nicotiana glutinosa cells by the cytokinin-biosynthesis gene from Agrobacterium tumefaciens (1987)
    Springer
    Planta 171 (1987), S. 539-548 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Cytokinin biosynthesis ; Auxin autonomy ; Nicotiana (auxin autonomy) ; Tumor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Agrobacteria carrying mutations at the auxin-biosynthesizing loci (iaaH and iaaM of the Ti plasmid) induce shoot-forming tumors on many plant species. In some cases, e.g. Nicotiana glutinosa L., tumors induced by such mutant strains exhibit an unorganized and fully autonomous phenotype. These characteristics are stable in culture at both the tissue and cellular level. We demonstrate that the cytokinin-biosynthesis gene (ipt) of the Ti plasmid is responsble for the induction of both auxin and cytokinin autonomy in N. glutinosa. Cloned cell lines carrying an ipt gene but lacking iaaH and iaaM are capable of accumulating indole-3-acetic acid. Interestingly, non-transformed N. glutinosa tissues exhibit an auxin-requiring phenotype when they are grown on medium supplemented with an exogenous supply of cytokinin. These results strongly indicate that exogenously supplied cytokinin does not mimic all the effects of the expression of the ipt gene in causing the auxin-autonomous growth of N. glutinosa cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00392304
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  • 78
    Digitale Medien
    Digitale Medien
    The Pseudomonas savastanoi tryptophan-2-mono-oxygenase is biologically active in Nicotiana tabacum (1987)
    Springer
    Planta 172 (1987), S. 555-562 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Auxin biosynthesis ; Indole-3-acetamide ; Pseudomonas ; Tryptophan-2-mono-oxygenase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract It has been proposed that the “eukaryotic” T-DNA-encoded indole-3-acetic acid (IAA) biosynthesis genes of Agrobacterium tumefaciens and their prokaryotic counterpart in Pseudomonas savastanoi originated from common ancestor genes. This paper provides additional evidence for the functional similarity between the gene products. We have demonstrated that a chimeric gene consisting of the coding sequence of the P. savastanoi tryptophan-2-mono-oxygenase (iaaM gene) and a plant promoter encodes an active enzyme in Nicotiana tabacum. Transformants obtained with this chimeric gene grew as a callus on hormone-free media. No stably transformed plantlets could be isolated. The callus tissues contained extremely high levels of indole-3-acetamide and slightly elevated levels of IAA. Either indole-3-acetamide by itself has a low auxin activity or, alternatively, it is converted aspecifically and at low rates into IAA. The P. savastanoi tryptophan-2-mono-oxygenase activity in plants is also able to detoxify the amino-acid analogue 5-methyltryptophan. This property can be used for positive selection of transformed calli.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00393874
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  • 79
    Digitale Medien
    Digitale Medien
    Two Agrobacterium tumefaciens genes for cytokinin biosynthesis: Ti plasmid-coded isopentenyltransferases adapted for function in prokaryotic or eukaryotic cells (1987)
    Springer
    Molecular genetics and genomics 210 (1987), S. 156-164 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Ti plasmids ; Cytokinin biosynthesis ; Isopentenyltransferase ; trans-zeatin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Tzs and ipt are two Ti plasmid genes coding for proteins with isopentenyltransferase (IPT) activity in vitro. We cloned both genes for protein expression in Escherichia coli and in Agrobacterium tumefaciens, and we investigated differences between the two genes by analysing the properties of the proteins in vitro and in vivo. In vitro, extracts with tzs or ipt-coded proteins had high IPT activity, and the enzymes were identical in most properties. The most important difference was detected in vivo: the tzs-encoded protein was very active in cytokinin production, while the ipt protein required overexpression in order to obtain measurable activity in bacteria. In both cases, rans-zeatin was the major product of the gene activity. Formation of this cytokinin requires a hydroxylase function in addition to the IPT reaction. No such activity could be ascribed to tzs or ipt-encoded proteins in vitro or in vivo, but cytokinin hydroxylase activity was detected in cells and extracts of E. coli, regardless of the presence or absence of the cytokinin genes. Based on these results it is proposed that both genes code for a single enzyme activity (isopentenyltransferase), that the genes and proteins are adapted for function either in bacteria (tzs) or in transformed plant cells (ipt), and that in both prokaryotic and eukaryotic cells hydroxylation to trans-zeatin is a function contributed by host enzymes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00337773
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  • 80
    Digitale Medien
    Digitale Medien
    Sequence context of the T-DNA border repeat element determines its relative activity during T-DNA transfer to plant cells (1987)
    Springer
    Molecular genetics and genomics 210 (1987), S. 338-346 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Ti plasmid ; T-DNA borders ; T-DNA transfer activity ; Plant cell transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We present a detailed analysis of the function of the right and left T-DNA border regions of the nopaline Ti plasmid of Agrobacterium tumefaciens. An avirulent deletion of the right border of the nopaline Ti plasmid (pGV3852) was used as an acceptor for 14 different T-DNA border constructs. The functional activities of these constructs were assayed by their ability to restore virulence, i.e. transformation on inoculated plants. Tumorigenicities were measured in several independent experiments over a 2 year period and the statistical significance of their relative levels was evaluated. The data indicate: (i) the entire sequence of the 25 bp direct repeat of the T-DNA is required to provide an efficient substrate for mediating T-DNA transfer events; deletion derivatives of either the conserved or the vaiable domain of the repeat are defective in T-DNA transfer; (ii) while the 25 bp direct repeat alone can promote the T-DNA transfer, the flanking sequences of the repeats enhance (on the right) or attenuate (on the left) their activity; and (iii) tumorigenicity measurements vary depending on the plant assay system: potato discs are more sensitive than wounded tobacco leaves in detecting differences in T-DNA border activity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00325703
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  • 81
    Digitale Medien
    Digitale Medien
    High meiotic stability of a foreign gene introduced into tobacco by Agrobacterium-mediated transformation (1987)
    Springer
    Molecular genetics and genomics 207 (1987), S. 171-175 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Nicotiana tabacum ; Agrobacterium ; Plant transformation ; Genetic stability ; Kanamycin resistance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Two lines of transgenic Nicotiana tabacum transformed to kanamycin resistance by means of a binary Agrobacterium vector containing a nos-npt gene were investigated over three generations. Southern hybridization and crossing analyses revealed that a single copy of T-DNA had integrated in each line and that the kanamycin resistance was regularly transmitted to the progeny as a monogenic dominant trait. Homozygous transgenic plants were fully fertile, morphologically normal and did not significantly differ from wild-type plants in the quantitative characters examined (plant height, flowering time). The two lines showed very low, but significantly different levels of meiotic instability: kanamycin-sensitive plants occurred among backcross progeny from homozygous transgenic plants with frequencies of 6/45,000 and 25/45,000, respectively. The sensitive plants arose independently of each other and thus resulted from meiotic rather than mitotic events. These findings demonstrate for the first time that integrated foreign genes can be transmitted to progeny with the high degree of meiotic stability required for commercial varieties of crop plants. They emphasize the importance of non-homologous integration and of avoiding co-integration of inactive gene copies for achieving meiotically stable transformants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00331506
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  • 82
    Digitale Medien
    Digitale Medien
    Agrobacterium rhizogenes T-DNA genes capable of inducing hairy root phenotype (1987)
    Springer
    Molecular genetics and genomics 209 (1987), S. 475-480 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Hairy root ; T-DNA ; Transgenic tobacco
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Segments of the TL-DNA of the agropine type Ri plasmid pRi 1855 encompassing single and groups of open-reading frames were cloned in the Ti plasmid-derived binary vector system Bin 19. Leaf disc infections on Nicotiana tabacum led to transformed plants, some of which showed typical hairy root phenotypes, such as the wrinkled leaf morphology, excessive and partially non geotropic root systems and the ability of leaf explants to differentiate roots in a hormone-free culture medium. Particularly interestingly, most of these traits were shown by plants transformed with a TL-DNA segment encompassing the single ORF 11, corresponding to the rolB locus. Hairy root can be induced by this latter T-DNA segment on wounded stems of tobacco plants; hairy root induction on carrot discs requires, on the contrary, a more complex complement of TL-DNA genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00331152
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  • 83
    Digitale Medien
    Digitale Medien
    Characterization and sequence determination of the replicator region in the hairy-root-inducing plasmid pRiA 4b (1987)
    Springer
    Molecular genetics and genomics 206 (1987), S. 1-8 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Ri plasmid ; Agrobacterium ; Mini replicon ; Replication origin ; Incompatibility
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Starting from a cosmid library of the 250 kb hairy root inducing plasmid pRiA 4b, a mini-pRiA 4b replicon of 4.6 kb was isolated. This mini-plasmid was stably maintained in Agrobacterium species and its replication characteristics, such as temperature-sensitive replication, copy number and incompatibility, were similar to those of the parental pRiA 4b. Analysis of deletion mutants indicated that almost the entire 4.6 kb region was required for autonomous replication. The nucleotide sequence of mini-pRiA 4b was determined by the chain-termination method. Three large open reading frames, which are likely to contribute to the replication of pRiA 4b, were identified in the same orientation along the sequence.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00326529
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  • 84
    Digitale Medien
    Digitale Medien
    Agrobacterium mediated transformation and regeneration of Populus (1987)
    Springer
    Molecular genetics and genomics 206 (1987), S. 192-199 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Poplar ; Transformation ; Agrobacterium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A plant transformation and regeneration system has been developed for Populus species. Leaf explants, from stabilized shoot cultures of a Populus hybrid NC-5339 (Populus alba x grandidentata), were co-cultivated with Agrobacterium tumefaciens on a tobacco nurse culture. Both oncogenic and disarmed strains of A. tumefaciens harboring a binary vector which contained two neomycin phophotransferase II (NPT II′) and one bacterial 5-enolpyruvylshikimate 3-phosphate (EPSP) synthase (aroA) chimeric gene fusions were used. Shoots did not develop when leaf explants were co-cultivated with the binary disarmed strain of A. tumefaciens. However, transformed plants with and without the wild type T-DNA were obtained using an oncogenic binary strain of A. tumefaciens. Successful genetic transformation was confirmed by NPT II′ enzyme activity assays, Southern blot analysis and immunological detection of bacterial EPSP synthase by Western blotting. This is the first report of a successful recovery of transformed plants of a forest tree and also the first record of insertion and expression of a foreign gene of agronomic importance into a woody plant species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00333574
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  • 85
    Digitale Medien
    Digitale Medien
    Absence in monocotyledonous plants of the diffusible plant factors inducing T-DNA circularization and vir gene expression in Agrobacterium (1987)
    Springer
    Molecular genetics and genomics 209 (1987), S. 221-226 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Monocotyledonous plants ; Plant factors ; T-DNA circularization ; vir gene expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary T-DNA circularization is one of the molecular events specifically induced in agrobacterial cells upon their infection of dicotyledonous plant cells. We developed a seedling co-cultivation procedure to determine whether or not monocotyledonous plants have the ability to induce T-DNA circularization and vir gene expression. Co-cultivation of Agrobacterium tumefaciens with seedlings of dicotyledonous plants showed that the circularization event takes place efficiently. The exudates and extracts of the seedlings also effectively induced T-DNA circularization and vir gene expression, indicating that dicotyledonous seedlings contain diffusible factors capable of inducing these molecular events. In contrast, neither T-DNA circularization nor vir gene expression was detectable when Agrobacterium was incubated with seedlings of monocotyledonous plants. Supplementing with acetosyringone, a known inducer of vir gene expression and T-DNA circularization, resulted in the induction of circularization during co-cultivation with monocotyledonous seedlings. These results indicate that the seedlings of monocotyledonous plants have no detectable amounts of diffusible inducers, unlike dicotyledonous seedlings. Therefore, it is unlikely that the vir genes are expressed in Agrobacterium inoculated in monocotyledonous plants. This may be one of the blocks in tumorigenesis of monocotyledonous plants by Agrobacterium.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00329646
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  • 86
    Digitale Medien
    Digitale Medien
    A plasmid sequence from Rhizobium leguminosarum 300 contains homology to sequences near the octopine TL-DNA right border (1987)
    Springer
    Molecular genetics and genomics 209 (1987), S. 580-584 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Rhizobium ; Agrobacterium ; TDNA ; Insertion sequence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The DNA sequence from a Rhizobium leguminosarum 300 (RL300) plasmid that contains homology to the Tc-DNA of Agrobacterium tumefaciens is described. The RL300 sequence has 78% homology to a 359 bp sequence in the Tc-DNA of pTi15955. The RL300 homology starts approximately 100 bp from the 24 bp border sequence of the TL-DNA and ends approximately 3 bp from an IS66 homolog in the Tc-DNA. An unusual feature of the RL300 homology is the presence of 81 bp direct repeats with Tc-DNA homology, separated by 201 bp. One end of each direct repeat has a 12 bp palindrome. Four cloned sequences of RL300 with homology to the T DNA region were hybridized to plasmid lysates of RL300 derivatives to determine the source of each plasmid. The sequenced homolog, originally on pRH228, was isolated from pRL7JI; the other 3 homologs were isolated from the transmissable plasmids pRL7JI (pRH235) and pRL8JI (pRH235 and pRH236).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00331166
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  • 87
    Digitale Medien
    Digitale Medien
    Strain and cultivar specificity in the Agrobacterium-soybean interaction (1987)
    Springer
    Plant cell, tissue and organ culture 8 (1987), S. 3-15 
    Details
    ISSN: 1573-5044
    Schlagwort(e): soybean ; plant transformation ; Agrobacterium ; Tiplasmid ; nopaline
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The response of Glycine max., G. soja and G. canescens genotypes to inoculation with different Agrobacterium strains was assessed. Percent visual tumor formation and tumor size varied widely among species and genotypes. Susceptible genotypes displayed a heightened response to nopaline strains of A. tumefaciens, relative to octopine, agropine, and A. rhizogenes strains. A nopaline strain engineered to contain a chimeric neomycin phosphotransferase II gene conferred kanamycin resistance to soybean tissue at kanamycine levels as high as 300 μg/ml.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00040728
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  • 88
    Digitale Medien
    Digitale Medien
    Rhizobium nod genes are involved in the induction of two early nodulin genes in Vicia sativa root nodules (1987)
    Springer
    Plant molecular biology 9 (1987), S. 171-179 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; nodulin gene expression ; Rhizobium ; root nodule ; sym-plasmid ; Vicia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Nodulin gene expresison was studied in Vicia sativa (common vetch) root nodules induced by several Rhizobium and Agrobacterium strains. An Agrobacterium transconjugant containing a R. leguminosarum symplasmid instead of its Ti-plasmid, that was previously shown to form “empty” nodules on pea, induced nodules on Vicia roots in which nodule cells were infected with bacteria. In the Vicia nodules induced by this transconjugant, two so-called early nodulin genes were found to be expressed, whereas in the nodules formed on pea the expression of only one early nodulin gene was detected. In both cases the majority of the nodulin genes was not expressed. Apparently, an intracellular location of the bacteria is not sufficient for the induction of the majority of the nodulin genes. All nodulin genes were expressed in nodules induced by cured Rhizobium strains containing cosmid clones that have a 10 kb nod region of the sym-plasmid in common. Since in tumours no nodulin gene expression was found at all, the Agrobacterium chromosome does not contribute to the induction of nodulin genes. Therefore it is concluded that the signal for the induction of the expression of the two Vicia early nodulin genes is encoded by the nod-region, and the signal involved in the induction of all other nodulin genes has to be located outside the sym-plasmid, on the Rhizobium chromosome. The apparent difference in early nodulin gene expression between pea and Vicia is discussed in the light of the usefulness of Agrobacterium transconjugants in the study of nodulin gene expression.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00015649
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  • 89
    Digitale Medien
    Digitale Medien
    The 5′ flanking DNA of a patatin gene directs tuber specific expression of a chimaeric gene in potato (1987)
    Springer
    Plant molecular biology 9 (1987), S. 345-375 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Patatin ; Solanum tuberosum L. ; Agrobacterium ; chimaeric gene ; chloramphenicol acetyltransferase (CAT)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A member of the patatin multigene family which encodes the major soluble tuber protein was isolated from potato cultivar Désirée. Analysis by strategic nucleotide sequencing demonstrated close homology to analogous regions of previously isolated patatin genomic clones from different cultivars. A 3.8-kb fragment containing the promoter and 5′ flanking DNA of the patatin gene was used to construct a transcriptional fusion gene with the coding DNA of the bacterial chloramphenicol acetyltransferase (CAT) gene and the polyadenylation/termination sequences of the nopaline synthase gene (nos). The chimaeric gene was reintroduced into potato cultivar Désirée by agrobacterial transformation of tissue slices. Regenerated transformed plants showed expression of the chimaeric gene (as determined by CAT activity) in tubers, but not in leaves, stems or roots of in vitro grown plants. Independent transformants did not show substantial variation in the level of induced tuber-specific CAT activity. Thus, information contained within 3.8 kb of the 5′ flanking DNA of the patatin gene analysed is sufficient to direct tuber-specific expression, largely independent of position effects.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00014911
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  • 90
    Digitale Medien
    Digitale Medien
    Neoplastic progression in crown gall in tobacco without elevated auxin levels (1986)
    Springer
    Planta 169 (1986), S. 454-461 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Auxin in tumor tissue ; Crown gall ; Nicotiana (cell transformation) ; Tumor morphology and progression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have isolated two stable variants from a crown-gall teratoma tissue of tobacco (Nicotiana tabacum L.) transformed by Agrobacterium tumefaciens strain A66, a mutant of the virulent A6 strain containing an insertion sequence in the tumor-inducing (Ti) plasmid at the locus coding for auxin biosynthesis. Normally tobacco cells transformed by strain A66 spontaneously form shoots in culture and will not grow on hormone-free medium unless shoots develop. The variant tissue lines, isolated from the teratoma tissue after prolonged culture in the dark, grew as friable and unorganized tissues on hormone-free growth medium. Growth of the variants was more sensitive to auxin feeding than growth of the parental teratoma line, and the auxin dose-response curves of the variant lines were similar to those obtained with A6-transformed tobacco cells. Southern blot analysis of DNA from the parental teratoma line and one of the variants showed no differences in copy number or organization of the oncogenic DNA sequence (T-DNA) transferred from the bacterium, indicating that the variant phenotype did not result from reversion of the A66 mutation. Radio-immunoassay analysis showed similar levels of indole-3-acetic acid (IAA) in the variants and parental teratoma line (3–50 and 38–42 pmol·(gFW)-1, respectively), whereas an A6-transformed cell line contained much higher IAA levels (150–1200 pmol·(g FW)-1). Low levels of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid in the variants and the parental teratoma line (〈5 nmol·(g FW)-1) as compared with that found in the A6-transformed line (〉100 nmol· (g FW)-1) provided additional, indirect evidence for low auxin levels in the variant lines. These results indicate that crown-gall teratoma tissues of tobacco may switch to the unorganized, auxin-sensitive phenotype without an increase in auxin content.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00392144
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  • 91
    Digitale Medien
    Digitale Medien
    TL-DNA from Agrobacterium rhizogenes plasmid pRi1855 reduces the osmotic pressure in transformed plants grown in vitro (1986)
    Springer
    Planta 168 (1986), S. 106-112 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Brassica (transformed plants) ; Genetic manipulation ; Osmotic pressure ; Potassium ; Solanum (transformed plants)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Growth, water content, osmotic pressure and solute content were examined for normal potato (Solanum tuberosum L. cv. Desiree) and a derivative (line D9X8a), which was genetically transformed with TL-DNA from Agrobacterium rhizogenes. Plants were grown (i) in vitro, (ii) in a growth chamber and (iii) in the field. In vitro, the transformed potato plants produced more biomass than the untransformed plants, partly because they had a higher water content. Potassium concentration and osmotic pressure were lower in cell sap extracted from the transformed potato shoots. In some cases the difference was as much as 50%. These differences were less clear, absent or reversed in plants from a growth chamber or from the field. In the field, however, transformed potato senesced early. It is suggested that a cellular basis for these observations may be changes induced by Ri TL-DNA expression products in plant membrane properties.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00407016
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  • 92
    Digitale Medien
    Digitale Medien
    Isozyme gene expression in potato tumors incited by Agrobacterium (1986)
    Springer
    Theoretical and applied genetics 72 (1986), S. 373-376 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Crown gall tumors ; Hairy root disease ; Potato ; Isozyme gene expression ; Agrobacterium ; Solanum tuberosum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Two plant tumors (crown galls and hairy roots) were experimentally provoked on potato cv. ‘Désirée’ by oncogenic strains of Agrobacterium tumefaciens and A. rhizogenes. A marked shift in the expression of some organ-specific genes occurred in crown galls derived from the central zone of tubers: two novel isozyme genes (Est-B and Pox-E) were expressed, two others (Est-C and Pox-F) were suppressed and the remaining ones were maintained in the original state. When the starting tissue was the stem segment, a smaller shift occurred, namely the activation of Adh-A and the suppression of Pox-F. In all cases, the isozyme profiles characterizing all crown galls, whatever their origin, were identical. Under normal aeration conditions, Adh-A was not expressed in either tumoral or non-tumoral roots. However, under the relative anaerobic conditions of in vitro cultures, a difference existed between both types of roots: Adh-A was expressed in normal but not in tumoral roots. This means that hairy roots can tolerate higher levels of anaerobiosis without giving rise to an anaerobic response. For the remaining isozymes, no alteration occurred in either organized (hairy root) or unorganized (crown gall) tumors, as compared to the corresponding non-tumoral tissues (normal root and callus, respectively).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00288575
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  • 93
    Digitale Medien
    Digitale Medien
    Multiple transformation of plant cells by Agrobacterium may be responsible for the complex organization of T-DNA in crown gall and hairy root (1986)
    Springer
    Molecular genetics and genomics 202 (1986), S. 388-393 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Ti plasmid ; Ri plasmid ; Opines ; T-DNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Inoculation of carrot discs and Lotus corniculatus plantlets with mixtures of different Agrobacterium rhizogenes or of A. rhizogenes and A. tumefaciens or with Agrobacterium strains harboring both an Ri and a modified Ti plasmid resulted in frequent multiple (pluribacterial) transformation of cells, as revealed by the mixed opine-type of hairy roots arising from them. Multiple transformation may account for the presence of dispersed T-DNA inserts in crown gall and hairy root lines. A plant genetic engineering strategy based on segregation of T-DNA inserts in the progeny of multiple transformants is proposed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00333267
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  • 94
    Digitale Medien
    Digitale Medien
    Genetic studies on the role of octopine T-DNA border regions in crown gall tumor formation (1986)
    Springer
    Molecular genetics and genomics 202 (1986), S. 312-320 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Plant transformation ; T-DNA borders ; T-DNA transfer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Crown gall tumors result from transfer and integration of the T-DNA from the Ti plasmid of Agrobacterium tumefaciens into plant nuclear DNA. In the present study, recombinant plasmids containing deletion and rearrangement deriviatives of the T-DNA region of the octopine Ti plasmid pTiA6 were tested in a binary tumorigenesis system (Hoekema et al. 1983) to determine the requirements for T-DNA border regions in tumor formation. Since two defined segments of the T-DNA region of octopine Ti plasmids can be detected in tumor DNA (the left (TL-) and right (TR-) DNA), four border regions exist in this Ti plasmid. Agrobacteria harboring plasmid constructs which contain a T-DNA gene capable of inciting tumors (gene 4, the tmr gene, which is involved in cytokinin biosynthesis) and various T-DNA border regions were tested for ability to cause tumors on Nicotiana glauca and other host plants. Such tmr constructs containing as their only border region the right border of either the TL-DNA or the TR-DNA are fully tumorigenic. Analogous tmr constructs containing only the TL-DNa left border region are not tumorigenic. These results do not depend on the orientation or position of the single border with respect to the tmr gene; furthermore, the TR-DNA right border can confer tumor-forming ability despite the presence of an intervening copy of the TL-DNA left border. These results for relatively small plasmids are contrasted with previously determined requirements for border regions in tumorigenesis by intact Ti plasmids. A model previously proposed by Wang et al. (1984) for the role of border regions in DNA transfer to plant cells is extended in order to explain the tumor-forming ability of plasmid constructs containing a single border region. The results of this study interpreted according to the model suggest that the octopine TL-DNA left border is defective in this DNA-transfer process.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00331657
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  • 95
    Digitale Medien
    Digitale Medien
    Characterisation of the T-region of the SAP-type Ti-plasmid pTiAT181: identification of a gene involved in SAP synthesis (1986)
    Springer
    Molecular genetics and genomics 202 (1986), S. 62-67 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Succinamopine ; T-DNA ; AT181
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The T-region of pTiAT181, a SAP(succinamopine)-type Ti-plasmid, is described and is found to be similar to that of the nopaline-type pTiT37. The two major differences are a deletion of 2.9 kb inside the left hand end of pTiAT181, and a right hand region comprised of DNA specific to pTiAT181. This novel DNA was shown by its transfer to plants using a binary vector, to encode an enzyme involved in the synthesis of SAP.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00330518
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  • 96
    Digitale Medien
    Digitale Medien
    Isolation and characterization of a light-inducible, organ-specific gene from potato and analysis of its expression after tagging and transfer into tobacco and potato shoots (1986)
    Springer
    Molecular genetics and genomics 205 (1986), S. 14-22 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Light induction ; Position effect ; Transformed plants ; Gene isolation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The isolation and analysis of several cDNAs and of one genomic clone encoding ST-LS1, a single-copy gene fromSolanum tuberosum with leaf/stem-specific, light-inducible expression, is described. The structure of the gene was determined by sequencing several overlapping partial cDNA clones as well as the genomic clone and by determining the transcription start site by RNA protection experiments. A “tagged” derivative of the gene, obtained by exon modification, was reintroduced into potato and into tobacco shoots usingAgrobacterium/Ti-plasmid vector systems. The modified gene was expressed in both tobacco and potato shoots giving rise to an RNA of approximately 1,200 nucleotides which exceeded the length of the RNA made from the endogenous gene by the expected size of the “tag” (470 nucleotides). The level of expression of the modified gene varied substantially between independent transformants. A high proportion of the transformants (20%–40%) synthesized as much RNA from the added gene as from the resident gene. Expression of the transferred gene was light induced. Qualitatively and quantitatively the expression of the introduced gene was similar in a homologous (potato) and in a heterologous, but related, cellular background (tobacco).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02428027
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  • 97
    Digitale Medien
    Digitale Medien
    A convenient autoradiographic technique for study of uptake of minerals by plant roots and the effects of environmental factors upon the process (1986)
    Springer
    Plant and soil 92 (1986), S. 299-302 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Agrobacterium ; Iron uptáke ; Siderophore
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary An autoradiographic procedure for the investigation of the uptake of minerals by plant roots and its application to the stimulation of uptake of ferric iron by agrobactin is described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02372643
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  • 98
    Digitale Medien
    Digitale Medien
    The role of bacterial attachment in the transformation of cell-wall-regenerating tobacco protoplasts by Agrobacterium tumefaciens (1985)
    Springer
    Planta 166 (1985), S. 300-308 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Nicotiana (protoplast transformation) ; Protoplast (attachment) of Agrobacterium) ; Transformation (protoplasts)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The presence of a newly formed primary cell wall was shown to be required for attachment and subsequent transformation of tobacco leaf protoplasts by Agrobacterium tumefaciens in cocultivation experiments. In these experiments both protoplasts at different stages after their isolation and cell-wall inhibitors were used. The specificity of Agrobacterium attachment was shown by using other kinds of bacteria that did not attach. By diminishing the concentration of divalent cations using ethylenediaminetetraacetic acid, neither attachment nor transformation was found; however, when more specifically the Ca2+concentration was lowered by ethylene glycol-bis (β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid, both phenomena occurred. Commercial lectins had no effect on binding, but this observation does not exclude the involvement of other lectins. Protoplasts isolated from various crown-gall callus tissues also developed binding sites, but when they were at the stage of dividing cells, attachment of agrobacteria was no longer observed. In this respect, cells from protoplasts of normal tobacco leaves behaved differently. Even 16 d after protoplast isolation, the dividing cells were still able to bind A. tumefaciens, while transformation was not detected. For transformation of 3-d-old tobacco protoplasts, a minimal co-cultivation period of 24 h was required, while optimal attachment took place within 5 h. It is concluded that the primary cell wall was sufficiently well formed that certain functional receptor molecules were available for attachment of Agrobacterium as the first step of a multistep process leading to the transformation of cells. The expression of bacterial functions required for attachment, moreover, was independent of the presence of Ti-plasmid.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00401165
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  • 99
    Digitale Medien
    Digitale Medien
    The effect of right terminal repeat deletion on the oncogenicity of the T-Region of pTiT37 (1985)
    Springer
    Plant molecular biology 5 (1985), S. 3-11 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; tumorigenicity ; border repeats ; tmr locus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A modified pTiT37 plasmid was constructed by deleting a 103 base fragment between an AhaIII and a Bc/I site. This fragment, located to the right of the nopaline synthase gene contains the right terminal 25 base pair repeat sequence which defines the right limit of the T-Region. The effect of this deletion was determined on a number of host plants. In contrast to previous reports, the deletion does not destroy tumorigenicity on all plant species. It had no effect on tumorigenicity when Linum usitatissimum was used as the test species and an attenuating effect when Kalanchoë tubiflora was used. Only when Nicotiana tabacum was used did the mutant appear avirulent. We propose from these data and the phenotype of those tumours that form, that a pseudo border located in the 3′ untranslated region of the ipt locus has been used to provide the right hand limit of the T-Region in the absence of the normal border.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00017868
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  • 100
    Digitale Medien
    Digitale Medien
    Transformation of lily by Agrobacterium (1955)
    Springer
    Euphytica 85 (1955), S. 97-100 
    Details
    ISSN: 1573-5060
    Schlagwort(e): Agrobacterium ; transformation ; lily ; β-glucuronidase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Lily cv. Harmony was inoculated with several Agrobacterium strains to study its susceptibility to Agrobacterium infection and transformation. Tumorous tissue formation on inoculated stem internodes of sterile-grown plantlets, as well as expression of a β-glucuronidase marker gene interrupted by an intron in cells of inoculated stem nodes, indicate that the monocotyledon Lilium is a host for Agrobacterium.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00023935
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