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  • 2005-2009
  • 1990-1994  (68)
  • 1955-1959  (4)
  • 1950-1954
  • 1890-1899
  • Agrobacterium
  • 1
    Digitale Medien
    Digitale Medien
    A reporter gene under the control of tms or aux promoters is differentially expressed in tobacco and barley protoplasts (1994)
    Springer
    Plant cell reports 13 (1994), S. 155-158 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Agrobacterium ; auxin biosynthesis genes ; barley and tobacco protoplasts ; transient expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Agrobacterium tumefaciens and some Agrobacterium rhizogenes strains possess auxin biosynthesis genes (tms and aux genes respectively), responsible for a de novo auxin biosynthetic pathway in transformed plant cells. A comparison is presented of the potential expression of these genes in a monocotyledonous (barley) and a dicotyledonous plant (tobacco). The promoters of the genes were translationally fused to the β-glucuronidase reporter gene and analysed in transient expression experiments. The tms and aux fusions were highly expressed in tobacco, but not in barley. However, the aux enhancer active in tobacco, conferred low β-glucuronidase expression in barley when fused to a truncated cauliflower mosaic virus 35S promoter. The results are discussed in relation to the differential responses to Agrobacterium infection in monocots and dicots.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00239883
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  • 2
    Digitale Medien
    Digitale Medien
    Stable expression of the GUS reporter gene in chrysanthemum depends on binary plasmid T-DNA (1994)
    Springer
    Plant cell reports 14 (1994), S. 59-64 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Agrobacterium ; transformation ; T-DNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Three chrysanthemum (Dendranthema grandiflora) cultivars were cocultivated with 2 Agrobacterium tumefaciens strains in combination with 4 pBIN19 derived binary plasmids, all carrying the Nosnptll selection gene and 35Sgus(intron) reporter gene. All binary plasmids transferred DNA to chrysanthemum explants but only pMOG410 gave good stable expression of GUS. This plasmid differs from the other plasmids in 2 aspects: 1) It carries a restored nptll gene and 2) the selection gene is positioned at the left border side of the reporter gene. Cocultivation with AGLO(pMOG410) yielded up to 13 GUS positive shoots per 100 explants. The presence of the gus and nptll gene in recovered shoots was confirmed by PCR and Southern blot analysis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00233300
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  • 3
    Digitale Medien
    Digitale Medien
    Agrobacterium-mediated transformation of commercial melon (Cucumis melo L., cv. Amarillo Oro) (1994)
    Springer
    Plant cell reports 13 (1994), S. 145-148 
    Details
    ISSN: 1432-203X
    Schlagwort(e): muskmelon ; gene transfer ; Agrobacterium ; regeneration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Cotyledon explants of muskmelon (Cucumis melo L., cv. Amarillo Oro) seedlings were co-cultivated with disarmed Agrobacterium tumefaciens strain LBA4404 that contained the binary vector plasmid pBI121.1. The T-DNA region of this binary vector contains the Nopaline synthase/neomycin phosphotransferase II (NPTII) chimeric gene for kanamycin resistance and the Cauliflower Mosaic Virus 35S/β-glucuronidase (GUS) chimeric gene. After infection, the cotyledon pieces were placed in induction medium containing 100 mg/l kanamycin. Putative transformed shoots were obtained, followed by the development of morphologically normal plantlets. The transgenic nature of regenerants was demonstrated by polymerase chain reaction, Southern blot analysis, plant growth on medium selective for the transgene (NPTII) and expression of the co-transformed GUS gene. Factors affecting the transformation procedure are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00239881
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  • 4
    Digitale Medien
    Digitale Medien
    Effect of plant genotype on the transformation of cultivated alfalfa (Medicago sativa) by Agrobacterium tumefaciens (1994)
    Springer
    Plant cell reports 13 (1994), S. 330-334 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Medicago sativa ; Alfalfa ; Transformation ; Agrobacterium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The trait for somatic embryogenesis is being introduced sexually into alfalfa (Medicago sativa) breeding populations to facilitate genetic transformation of this crop. Cocultivation experiments were conducted with an agronomically-improved embryogenic clone from one such population as well as with two other embryogenic clones, one of which was the source of the embryogenic trait in the breeding populations. Transgenic plants were produced from the agronomically-improved clone whereas none were produced from the other two clones. Among the 16 transgenic plants analyzed there was a range in both copy number and number of integration sites for the NPT-II gene; those plants regenerated after a prolonged selection phase in vitro generally had the highest numbers in both respects. There was no evidence of sectoral chimerism of the transgene in a subsample of transgenic plants analyzed by PCR.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00232631
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  • 5
    Digitale Medien
    Digitale Medien
    Identification of Agrobacterium strains by PCR-RFLP analysis of pTi and chromosomal regions (1994)
    Springer
    Archives of microbiology 161 (1994), S. 300-309 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Agrobacterium ; 16S rDNA ; 16S rDNA-23S rDNA Intergenic spacer ; tmr Gene ; nos Gene ; virA Gene ; virB2 Gene ; Polymerase chain reaction ; Restriction fragment length polymorphism ; Crown gall
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Chromosomes and Ti plasmids of 41 Agrobacterium strains, belonging to biovars 1, 2, 3, and Agrobacterium rubi species were characterized by the restriction fragment length polymorphism of PCR-amplified DNAs. Profiles that were obtained by the analysis of the amplified 16S rDNA confirmed the grouping of the strains according to their species. Higher polymorphism was detected in the intergenic spacer between the 16S rDNA and 23S rDNA genes, allowing efficient discrimination of strains. Identification of most strains was possible, and the genetic relatednesses of Agrobacterium strains could be estimated. The analysis of the plasmid Ti encoded regions between the tmr and nos genes, and the virA and virB2 genes, allowed fingerprinting of Ti plasmids. Genomic typing by the rapid PCR-RFLP method is thus shown to be useful for an independant identification of strains and of the conjugative Ti plasmids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00303584
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  • 6
    Digitale Medien
    Digitale Medien
    Several phenotypic changes in the cell envelope of Agrobacterium tumefaciens chvB mutants are prevented by calcium limitation (1994)
    Springer
    Archives of microbiology 161 (1994), S. 310-315 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Agrobacterium ; β-1,2-Glucan ; chvB Mutants—Ca2+
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The chvB gene of Agrobacterium tumefaciens encodes a 235 kDa proteinaceous intermediate involved in the synthesis of β-1,2-glucan. chvB mutants show a pleiotropic phenotype. Besides not to produce cyclic β-1,2-glucan, chvB mutants have been reported to be avirulent, attachment-deficient, and nonmotile. In this study we report additional differences from the parent strain, probably all linked to changes in the cell envelope. This pleiotropic phenotype — except for attachment and virulence — could largely be prevented by growing chvB cells with low levels of calcium. Although a role for β-1,2-glucan in osmoadaptation has been proposed, the mode of action of β-1,2-glucan is not known. We speculate that in A. tumefaciens β-1,2-glucan stabilizes membranes, which would be important especially in hypotonic media containing calcium.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00303585
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  • 7
    Digitale Medien
    Digitale Medien
    Localization of the VirA domain involved in acetosyringone-mediatedvir gene induction inAgrobacterium tumefaciens (1994)
    Springer
    Plant molecular biology 25 (1994), S. 899-907 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; gene regulation ; sensor protein ; signal transduction ; VirA protein ; acetosyringone
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The VirA protein ofAgrobacterium tumefaciens is thought to be a receptor for plant phenolic compounds such as acetosyringone. Although it is not known whether the interaction between VirA and the phenolics is direct or requires other phenolic-binding proteins, it is shown in this study that the first 280 amino acids of the VirA protein are not essential for the acetosyringone mediatedvir gene induction response. Considering the fact that the cytoplasmic region between the amino acids 283 and 304 is highly conserved between the different VirA proteins, and that deletion of this region abolishes VirA activity, we suggest that the acetosyringone receptor domain is located in this cytoplasmic domain of the VirA protein.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00028884
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  • 8
    Digitale Medien
    Digitale Medien
    The small, versatilepPZP family ofAgrobacterium binary vectors for plant transformation (1994)
    Springer
    Plant molecular biology 25 (1994), S. 989-994 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; binary vectors ; gentamycin resistance ; kanamycin resistance ; tobacco
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The newpPZP Agrobacterium binary vectors are versatile, relatively small, stable and are fully sequenced. The vectors utilize the pTiT37 T-DNA border regions, the pBR322bom site for mobilization fromEscherichia coli toAgrobacterium, and the ColE1 and pVS1 plasmid origins for replication inE. coli and inAgrobacterium, respectively. Bacterial marker genes in the vectors confer resistance to chloramphenicol (pPZP100 series) or spectinomycin (pPZP200 series), allowing their use inAgrobacterium strains with different drug resistance markers. Plant marker genes in the binary vectors confer resistance to kanamycin or to gentamycin, and are adjacent to the left border (LB) of the transferred region. A lacZ α-peptide, with the pUC18 multiple cloning site (MCS), lies between the plant marker gene and the right border (RB). Since the RB is transferred first, drug resistance is obtained only if the passenger gene is present in the transgenic plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00014672
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  • 9
    Digitale Medien
    Digitale Medien
    Purification and partial characterization of a glycoprotein from pea (Pisum sativum) with receptor activity for rhicadhesin, an attachment protein of Rhizobiaceae (1994)
    Springer
    Plant molecular biology 24 (1994), S. 171-183 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; attachment ; plant receptor ; rhicadhesin ; Rhizobium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Attachment of Rhizobium and Agrobacterium bacteria to cells of their host plants is a two-step process. The first step, direct attachment of bacteria to the plant cell wall, is mediated by the bacterial protein rhicadhesin. A putative plant receptor molecule for rhicadhesin was purified from cell walls of pea roots using a bioassay based on suppression of rhicadhesin activity. This molecule appeared to be sensitive to treatments with pronase or glycosidase. Its isoelectric point is 6.4, and its apparent molecular mass was estimated to be 32 kDa before and 29 kDa after glycosidase treatment, as determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and ultrafiltration. The sequence of the first 29 N-terminal amino acids was determined: A-D-A-D-A-L-Q-D-L-C(?)-V-A-D-Y-A-S-V-I-L-V-N-G-F-A-S-K(Q)-(P/Q)-(L)-(I). No homology with known proteins was found. In the course of this research project the extracellular matrix protein vitronectin was reported to inhibit attachment of A. tumefaciens to carrot cells [29]. A variety of adhesive proteins, including vitronectin, contain a common cell attachment determinant with the sequence R-G-D. Since we could not detect other cell wall components able to suppress rhicadhesin activity, and since an R-G-D containing hexapeptide was also active as a receptor, we speculate that the plant receptor for rhicadhesin is a glycoprotein containing an R-G-D attachment site.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00040583
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  • 10
    Digitale Medien
    Digitale Medien
    A simple and efficient gene transfer system of trifoliate orange (Poncirus trifoliata Raf.) (1994)
    Springer
    Plant cell reports 13 (1994), S. 541-545 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Trifoliate orange ; Epicotyl segment ; Agrobacterium ; Transformation ; rolC promoter ; β-glucuronidase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A simple and efficient gene transfer system of trifoliate orange (Poncirus trifoliata Raf.) was developed using epicotyl segments. The segments were infected with Agrobacterium harboring the binary vector pBI121 or pBI101-O12-p1. Both vectors contained the neomycin phosphotransferase II (NPTII) and the β-glucuronidase (GUS) genes. In the plasmid pBI101-O12-p1, the GUS gene was directed to the promoter region of ORF12 (rolC) of the Ri plasmid. On a selection medium containing 100 or 200 μg/ml kanamycin, adventitious shoots were formed from 21.7–44.6% of the segments. Histochemical GUS assay showed that 55.4–87.7% of the shoots expressed the GUS gene. The stable integration of this gene was also confirmed by polymerase chain reaction (PCR) analysis and by Southern blot analysis. When the pBI101-O12-p1 plasmid was used, the GUS activity was found to be located in phloem cells of leaf, stem and root. More than 100 transformed plants were obtained using this method within 2–3 months.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234507
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  • 11
    Digitale Medien
    Digitale Medien
    Expression and inheritance pattern of two foreign genes in petunia (1994)
    Springer
    Theoretical and applied genetics 88 (1994), S. 433-440 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Agrobacterium ; Transformation ; Gene expression ; Petunia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Transgenic petunia (Petunia hybrida Vilm.) plants were obtained from Agrobacterium-mediated shoot apex transformation. Studies at the phenotypic as well as molecular level established both the presence of the NPT II (neomycin phosphotransferase II) and GUS (β-glucuronidase) genes and their level of activity. Twenty-nine primary transformed plants showed varying patterns of phenotype expression of both genes. NPT II and GUS expression in 7 primary plants over a 4-month interval showed varying levels of gene expression within and among individual plants. All primary transgenic plants were self-pollinated and backcrossed to establish the inheritance patterns of both genes. Mendelian and non-Mendelian inheritance patterns for both genes were observed. Analysis of the progeny showed poor transmission of the foreign genes through the pollen especially when two or more bands were present in the Southern hybridization. Most plants whose progeny segregated in Mendelian ratios for either the NPT II or GUS gene had just one copy of the gene. In this study where both foreign genes were examined in both self and test crosses, no transgenic plant showed Mendelian patterns of inheritance for both foreign traits.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00223657
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  • 12
    Digitale Medien
    Digitale Medien
    Cybridization in Nicotiana tabacum L. using double inactivation of parental protoplasts and post-fusion selection based on nuclear-encoded and chloroplast-encoded marker genes (1994)
    Springer
    Theoretical and applied genetics 88 (1994), S. 1017-1022 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Agrobacterium ; Iodoacetamide Nicotiana protoplast fusion ; Nitrosomethyl urea Rhodamine 6G ; X-irradiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract An effective selection system preceded by double inactivation of parental protoplasts was used to transfer Nicotiana suaveolens Leh. cytoplasmic male sterility into a commercial tobacco (N. tabacum L.) breeding line. Mesophyll protoplasts from transformed plants of N. tabacum cultivar WZ2-3-1-1 possessing a neomycin phosphotransferase II gene were used as the nuclear donors, while those isolated from N. suaveolens plants carrying a chloroplast mutation for resistance to spectinomycin, induced using nitrosomethyl urea, were the cytoplasm donors in somatic cybridizations. Prior to fusion, nuclear donor protoplasts were inactivated with iodoacetamide or rhodamine 6G, while those of the cytoplasm donor were inactivated by X-irradiation. The resultant microcalli were cultured on a shoot regeneration medium containing both kanamycin and spectinomycin to select cybrids. Only regenerants that had typical characteristics of the N. tabacum cultivar were selected for transfer to the glasshouse. Four putative cytoplasmic male-sterile (CMS) plants, out of a total of 44 regenerated plants transferred to the glasshouse, were obtained. Intraspecific somatic transfers of the CMS trait between N. tabacum cultivars with distinctlydifferent morphologies using single inactivation and nonselective shoot regeneration medium were demonstrated. The implications of the results for practical tobacco breeding as a means of circumventing lengthy backcrossing procedures are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00220810
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  • 13
    Digitale Medien
    Digitale Medien
    Transformation of protoplasts and intact cells from slowly growing embryogenic callus of wheat (Triticum aestivum L.) (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 577-582 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Wheat ; Transformation ; Agrobacterium ; Electroporation ; Polyethylene glycol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A procedure for culturing protoplasts from slowly growing embryogenic calli of wheat was developed. The procedure was dependent on the ability to isolate large numbers of culturable protoplasts from slowly growing embryogenic callus. Approximately 68% of the isolated protoplasts divided, and 22% formed colonies; of the latter, 67% continued to proliferate. Plating efficiency was reduced when protoplasts were transformed by polythylene glycol, electroporation, and/or Agrobacterium. Intact cells were also directly transformed by electroporation. Direct electroporation of the Agrobacterium binary vector into intact cells resulted in a significant increase of GUS activity over the control.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00222451
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  • 14
    Digitale Medien
    Digitale Medien
    T-DNA-insert-independent mutations induced in transformed plant cells duringAgrobacterium co-cultivation (1994)
    Springer
    Transgenic research 3 (1994), S. 317-325 
    Details
    ISSN: 1573-9368
    Schlagwort(e): Agrobacterium ; mutagenesis ; Nicotiana plumbaginifolia ; nitrate reductase ; ploidy ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Transformation frequencies were determined for 1n, 2n, and 4n Nicotiana plumbaginifolia protoplast cultures inAgrobacterium-mediated gene transfer experiments. An unexpected large drop (50%) in plating efficiencies was observed in the non-selected (control) 1n populations after transformation treatment with virulent strains. This effect was not observed in the 2n or 4n cultures or in the 1n cultures when treated with avirulent bacteria. The mortality was disproportionally high and could not be explained by the low (0.1–0.5%) transformation efficiency in the 1n population, indicating mutagenesis of the cell populations independently from the T-DNA insertions. Mutagenesis was also indicated in gene tagging experiments where nitrate reductase-deficient (NR−) mutants were selected from haploidNicotiana plumbaginifolia protoplasts, as well as from leaf disc cultures or protoplasts of diploid plants that were heterozygotic for a mutation either in the NR apoenzyme gene (nia/wt) or one of the molybdenum-containing cofactor genes (cnxA/wt), afterAgrobacterium co-cultivation. The chlorate-resistant isolates were tested for the T-DNA-specific kanamycin resistance trait only after NR-deficiency had been established. Thirty-nine independent NR-deficient mutants were analysed further by Southern blot hybridization. There was no indication of integrated T-DNA sequences in the mutated NR genes, despite the fact that NR-deficient cells were found more frequently in cell populations which became transformed during the treatment than in the populations which did not. These observations suggest that transformation-competent cells undergo mutagenesis during theAgrobacterium gene transfer process not only as a result of stable integration events, but also through accompanying events that do not result in major changes in the mutated loci. The nature of these changes at the molecular level remains to be elucidated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01973592
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  • 15
    Digitale Medien
    Digitale Medien
    Spurious localizations of diX-indigo microcrystals generated by the histochemical GUS assay (1994)
    Springer
    Transgenic research 3 (1994), S. 176-181 
    Details
    ISSN: 1573-9368
    Schlagwort(e): Agrobacterium ; β-glucuronidase ; cytoenzymology ; reporter gene ; transgenic plants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract For several models expressing theuidA orgus reporter gene with or without a presequence for mitochondrial targeting, we have demonstrated that the compartmentation of β-glucuronidase (E.C. 3.2.1.31) activity was not in agreement within situ localization of the diX-indigo microcrystals generated by the cytoenzymological GUS assay. These crystals were generally associated with the various cytomembranes and lipid inclusions. Experiments with purified β-glucuronidase or withgus-expressing bacteria incubated with 5-bromo-4-chloro-3-indolyl-β-d-glucuronide and maize oil-phosphate buffer emulsion indicated that the intermediate products resulting from the GUS assay actively diffused and crystallized preferentially in association with lipids, sometimes far from the site of enzyme activity. This phenomenon could not be suppressed by the addition of potassium ferricyanide in the incubation medium. These findings are discussed with regard to previously reported biochemical and histochemical data on animal tissues, and focus on the necessity for caution in studies of tissue-specific gene expression using the GUS assay, particularly for lipid-rich plant models.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01973985
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  • 16
    Digitale Medien
    Digitale Medien
    The NocR repressor-activator protein regulates expression of the nocB and nocR genes of Agrobacterium tumefaciens (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 367-373 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Nopaline ; Repressor Activator ; LysR family
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The NocR protein of Agrobacterium tumefaciens was found to regulate expression of the divergently transcribed nocB and nocR genes of the pTiT37 nopaline catabolism (noc) region. Experiments using the firefly luciferase (luc) gene as reporter demonstrated that NocR represses and activates transcription from the nocB promoter in the absence and presence of nopaline, respectively. NocR also negatively autoregulates its own synthesis irrespective of the presence of nopaline. Regulation of expression of both nocB and nocR is mediated by binding of the NocR protein to the nocR promoter. A 12 by symmetrical sequence, which lies 3 by downstream of the −10 hexamer of the nocR promoter, was confirmed to be essential for binding of the NocR protein. Functional localization of the nocB and nocR promoters verified that they do not overlap at all, and that the interrupted dyad, at which NocR binds, is 137 by upstream of the regulated nocB promoter. The in vivo and in vitro results described here and those published previously suggest that a novel type of regulatory mechanism, which may involve changes in DNA topology, controls gene expression in the noc operon of pTiT37.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00286688
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  • 17
    Digitale Medien
    Digitale Medien
    Agrobacterium vitis nopaline Ti plasmid pTiAB4: relationship to other Ti plasmids and T-DNA structure (1994)
    Springer
    Molecular genetics and genomics 245 (1994), S. 493-505 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Bacterial evolution ; Nopaline strains ; Ti plasmids ; Grapevine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The Ti plasmid of the Agrobacterium vitis nopaline-type strain AB4 was subcloned and mapped. Several regions of the 157 kb Ti plasmid are similar or identical to parts of the A. vitis octopine/cucumopine (o/c)-type Ti plasmids, and other regions are homologous to the nopaline-type Ti plasmid pTiC58. The T-DNA of pTiAB4 is a chimaeric structure of recent origin: the left part is 99.2% homologous to the left part of the TA-DNA of the o/c-type Ti plasmids, while the right part is 97.1 % homologous to the right part of an unusual nopaline T-DNA recently identified in strain 82.139, a biotype Il strain from wild cherry. The 3′ non-coding regions of the ipt genes from pTiAB4 and pTi82.139 are different from those of other ipt genes and contain a 62 by fragment derived from the coding sequence of an ipt gene of unknown origin. A comparison of different ipt gene sequences indicates that the corresponding 62 by sequence within the coding region of the AB4 ipt gene has been modified during the course of its evolution, apparently by sequence transfer from the 62 by sequence in the 3′ non-coding region. In pTi82.139 the original coding region of the ipt gene has remained largely unmodified. The pTiAB4 6b gene differs from its pTi82.139 counterpart by the lack of a 12 by repeat in the 3′ part of the coding sequence. This leads to the loss of four glutamic acid residues from a series of ten. In spite of these differences, the ipt and 6b genes of pTiAB4 are functional. Our results provide new insight into the evolution of Agrobacterium Ti plasmids and confirm the remarkable plasticity of these genetic elements. Possible implications for the study of bacterial phylogeny are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00302262
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  • 18
    Digitale Medien
    Digitale Medien
    Genetic manipulation in vesicular-arbuscular mycorrhizal fungi (1994)
    Springer
    Plant and soil 159 (1994), S. 171-178 
    Details
    ISSN: 1573-5036
    Schlagwort(e): Agrobacterium ; Gigaspora margarita ; Glomus intraradix ; PCR ; mycorrhizae ; rDNA gene ; root organ culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The symbiosis between vesicular-arbuscular mycorrhizal (VAM) fungi and host plants develops after successful interactions between both partners. These interactions probably involve signal molecules produced by the host plant, by the fungi, or by both. So far the biotrophic status of VAM fungi has hampered the understanding of the processes regulating their physiology. However, among different methods for co-cultivating VAM fungi, root organ cultures (ROC) appear to be a useful technique for studying VAM development. This system has been useful in defining the nutritional requirements of VAM fungi in the precolonization stage and in obtaining axenic fungal material in various developmental stages. The work discussed here focuses on the application of Polymerase Chain Reaction (PCR) technology and the potential of promoting hyphal growth in the absence of the plant. These techniques are being used to study VAM fungi in two main areas. The first concerns the determination of the DNA sequences coding for the SSU ribosomal RNA of two VAM fungi. This approach has allowed the design of specific primers for the rapid identification and quantification of VAM fungi. The second area of research concerns the potential use of PCR technology to study selective expression of specific genes during fungal spore development in defined in vitro conditions. The achievement of this future prospect depends on the ability to prepare PCR-based cDNA libraries from small amounts of fungal material after stimulation of hyphal growth with CO2 and plant flavonols.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00000106
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  • 19
    Digitale Medien
    Digitale Medien
    Traits of transgenic Atropa belladonna doubly transformed with different Agrobacterium rhizogenes strains (1994)
    Springer
    Plant cell, tissue and organ culture 38 (1994), S. 257-262 
    Details
    ISSN: 1573-5044
    Schlagwort(e): Agrobacterium ; Atropa belladonna ; double transformation ; phytohormone content ; tropane alkaloids ; viviparous leaves
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Hairy root cultures of Atropa belladonna L. were established by infection either with Agrobacterium rhizogenes ATCC 15834 or MAFF 03-01724, and transgenic plants were obtained from both hairy root cultures. Doubly transformed roots were induced by re-infection of the leaf segments of transgenic Atropa belladonna plants (A. rhizogenes 15834) with MAFF 03-01724. Shoots and viviparous leaves were regenerated from the doubly transformed roots. The genetic transformation was determined by the opine assay (agropine, mannopine and/or mikimopine) and polymerase chain reaction. Physiological changes and tropane alkaloid biosynthesis in the hairy roots (singly and doubly transformed) were investigated. The alkaloid content in the doubly transformed root strain was intermediate as compared to the root strains which were singly transformed. On the other hand endogenous IAA levels in doubly transformed roots were significantly decreased compared to both singly transformed roots.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00033885
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  • 20
    Digitale Medien
    Digitale Medien
    Transformation of peas (1993)
    Springer
    Plant cell reports 12 (1993), S. 180-183 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Peas ; Seed ; Transformation ; Agrobacterium ; Meristems
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The lateral cotyledonary meristems present in germinating seed were inoculated with a non-oncogenic strain of A. tumefaciens carrying a gene conferring kanamycin resistance as a selectable marker and a β-glucuronidase sequence as a reporter gene. Kanamycin resistant plants were derived from the meristems and shown to be transformed on the basis of Southern blots, polymerase chain reaction analysis and tests for β-glucuronidase activity. The plants were fertile and tests of their progeny confirmed the transmission of integrated sequences through a sexual generation. This transformation method has the merit of an unlimited supply of material for inoculation and a relatively short time scale from inoculation to the production of rooted plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00239102
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  • 21
    Digitale Medien
    Digitale Medien
    Phenotype and hormonal status of transgenic tobacco plants overexpressing the rolA gene of Agrobacterium rhizogenes T-DNA (1993)
    Springer
    Plant molecular biology 23 (1993), S. 1199-1210 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; growth retardants ; plant hormones ; Ri plasmid ; transgenic tobacco
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The rolA gene of the TL-DNA of Agrobacterium rhizogenes Ri-plasmid plays a major role in establishing the hairy root syndrome in transgenic plants. Transgenic tobacco plants (Nicotiana tabacum L.) expressing constitutively the rolA gene under the transcriptional control of the 35S RNA promoter show pronounced phenotypical alterations. P35S-rolA transgenic tobacco plants are characterized by stunted growth, dark green wrinkled leaves with an altered length-to-width ratio, condensed inflorescences, retarded onset of flowering, a reduced number of flowers and shortened styles. To investigate whether the pleiotropic alterations of growth and development are linked to an altered hormonal status we have compared the immunoreactive content of indole-3-acetic acid, cytokinins, abscisic acid, gibberellin and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) of seedlings and different tissues of P35S-rolA transgenic plants, transgenic plants expressing the rolA gene under control of its own phloem-specific promoter and wild-type plants. Multiple tissue-specific alterations of phytohormone concentrations are the consequence of rolA gene activity. Changes of phytohormonal content can explain part of the rolA-induced phenotypic alterations. Most strikingly, in young and fully developed leaves of rolA and P35S-rolA transgenic clones a 40–60% reduction of immunoreactive gibberellin A1 was found, as compared to wild-type leaves. Treatment of wild-type tobacco plants with inhibitors of gibberellin biosynthesis phenotypic alterations similar to those of rolA transgenic plants. This suggests that the reduction of gibberellic acid content is indirectly but causally involved in rolA-induced alterations of stem elongation and planar leaf blade growth.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00042353
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  • 22
    Digitale Medien
    Digitale Medien
    Agrobacterium-mediated production of transgenic rice plants expressing a chimeric α-amylase promoter/β-glucuronidase gene (1993)
    Springer
    Plant molecular biology 22 (1993), S. 491-506 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; α-amylase promoter ; α-glucuronidase ; Oryza sativa ; potato suspension culture ; transgenic rice
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have successfully transferred and expressed a reporter gene driven by an α-amylase promoter in a japonica type of rice (Oryza sativa L. cv. Tainung 62) using the Agrobacterium-mediated gene transfer system. Immature rice embryos (10–12 days after anthesis) were infected with an Agrobacterium strain carrying a plasmid containing chimeric genes of β-glucuronidase (uidA) and neomycin phosphotransferase (nptII). Co-incubation of potato suspension culture (PSC) with the Agrobacterium inoculum significantly improved the transformation efficiency of rice. The uidA and nptII genes, which are under the control of promoters of a rice α-amylase gene (αAmy8) and Agrobacterium nopaline synthase gene (nos), respectively, were both expressed in G418-resistant calli and transgenic plants. Integration of foreign genes into the genomes of transgenic plants was confirmed by Southern blot analysis. Histochemical localization of GUS activity in one transgenic plant (R0) revealed that the rice α-amylase promoter functions in all cell types of the mature leaves, stems, sheaths and roots, but not in the very young leaves. This transgenic plant grew more slowly and produced less seeds than the wild-type plant, but its R1 and R2 progenies grew normally and produced as much seeds as the wild-type plant. Inheritance of foreign genes to the progenies was also confirmed by Southern blot analysis. These data demonstrate successful gene transfer and sexual inheritance of the chimeric genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00015978
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  • 23
    Digitale Medien
    Digitale Medien
    Quantification of indole-3-acetic acid in untransformed and Agrobacterium rhizogenes-transformed pea roots using gas chromatography mass spectrometry (1993)
    Springer
    Planta 189 (1993), S. 55-59 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Auxin ; Pisum (hairy roots) ; Root (auxin levels) ; Transformation (root)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Root segments of Pisum sativum L. were transformed by several strains of Agrobacterium rhizogenes. The resulting hairy roots, as well as apical segments from untransformed pea roots, were used to initiate root lines cultured in vitro. Levels of free IAA were quantified in the sub-cultured lines by gas-chromatography coupled to mass spectrometry, using selected ion monitoring. For most of the cultured untransformed and transformed root lines the IAA content was very small, compared with levels in untransformed intact primary roots. However, an agropine-type hairy root line (incited by strain 15834) contained significantly higher amounts of IAA. The peculiar phenotype of this root line (abundant production of calli) appears to be associated with an increased IAA level, as opposed to most of the hairy root lines, where the extensive secondary root proliferation associated with the hairy-root disease cannot be merely attributed to a markedly enhanced IAA content.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00201343
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  • 24
    Digitale Medien
    Digitale Medien
    Variation amongst Brassica juncea cultivars for regeneration from hypocotyl explants and optimization of conditions for Agrobacterium-mediated genetic transformation (1993)
    Springer
    Plant cell reports 12 (1993), S. 462-467 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Brassica juncea ; hypocotyl ; plant regeneration ; Agrobacterium ; genetic transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Twelve cultivars of Brassica juncea grown in different agroclimatic regions of the world were tested for their ability to regenerate in vitro from hypocotyl explants and, accordingly, were divided into three groups. One group of cultivars regenerated on MS medium supplemented with 2,4-D, BAP and with NAA, BAP combinations; another group regenerated only on MS with 2,4-D, BAP; and the third group showed very low regeneration on both of these combinations. Inclusion of silver nitrate in the medium was essential for high frequency of regeneration. In general, Indian cultivars were more responsive than the cultivars of CIS and Australian origin. Using the media optimal for regeneration and an Agrobacterium-based binary vector carrying hpt and gus-intron genes, conditions for genetic transformation of B. juncea hypocotyl explants were optimized. Transformation frequencies, identified by GUS staining at the initial stages of growth, were lower on MS medium with 2,4-D, BAP than on MS with NAA, BAP. Plants resistant to 20 μg/ml hygromycin were regenerated at a frequency of 11–36% from hypocotyl explants and were shown to be transformed by Southern blotting, GUS staining and progeny analysis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234713
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  • 25
    Digitale Medien
    Digitale Medien
    Genetic transformation of Brassica nigra by agrobacterium based vector and direct plasmid uptake (1993)
    Springer
    Plant cell reports 12 (1993), S. 418-421 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Brassica nigra ; Transformation ; Agrobacterium ; Direct gene transfer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Genetic transformation systems have been established for Brassica nigra (cv. IC 257) by using an Agrobacterium binary vector as well as by direct DNA uptake of a plasmid vector. Both the type of vectors carried nptII gene and gus gene. For Agrobacterium mediated transformation, hypocotyl tissue explants were used, and up to 33% of the explants produced calli on selection medium. All of these expressed B-glucuronidase gene on histochemical staining. Protoplasts isolated from hypocotyl tissues of seedlings could be transformed with a plasmid vector by FEG mediated uptake of vector DNA. A number of fertile kanamycin resistant plants were obtained using both the methods, and their transformed nature was confirmed by Southern blot analysis and histochemical staining for GUS. Backcrossed and selfed progenies of these transformed plants showed the presence of npt and gus genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234704
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  • 26
    Digitale Medien
    Digitale Medien
    NewAgrobacterium helper plasmids for gene transfer to plants (1993)
    Springer
    Transgenic research 2 (1993), S. 208-218 
    Details
    ISSN: 1573-9368
    Schlagwort(e): Agrobacterium ; plant transformation ; helper plasmids ; host range ; Ti plasmid ; T-DNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We describe the construction of new helper Ti plasmids forAgrobacterium-mediated plant transformation. These plasmids are derived from three differentAgrobacterium tumefaciens Ti plasmids, the octopine plasmid pTiB6, the nopaline plasmid pTiC58, and the L,L-succinamopine plasmid pTiBo542. The T-DNA regions of these plasmids were deleted using site-directed mutagenesis to yield replicons carrying thevir genes that will complement binary vectorsin trans. Data are included that demonstrate strain utility. The advantages ofAgrobacterium strains harbouring these ‘disamed’ Ti plasmids for plant transformation viaAgrobacterium are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01977351
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  • 27
    Digitale Medien
    Digitale Medien
    Localization of target cells and improvement ofAgrobacterium-mediated transformation efficiency by direct acetosyringone pretreatment of carrot root discs (1993)
    Springer
    Protoplasma 174 (1993), S. 10-18 
    Details
    ISSN: 1615-6102
    Schlagwort(e): Acetosyringone ; Agrobacterium ; Carrot ; Cell cycle ; GUS assay ; Indole acetic acid levels
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Localization of target cells forAgrobacterium-mediated transformation in the carrot root disc model has been achieved after inoculation with a disarmedA. tumefaciens strain harbouring a GUS-intron construct. The first GUS positive cells could be detected on both sides of the discs 48 h after inoculation. The transformed cells were always more numerous on the apical side, mainly localized in the intrafascicular cambium and in the immature phloem strands. The kinetics of free endogenous IAA levels on both sides after wounding have been determined, indicating that rapid IAA accumulation on the apical side was not simply due to polar migration from the basal side. Attempts to optimize transformation efficiency were made by pretreating the discs with various concentrations of acetosyringone (AS) and/or naphthalene acetic acid (NAA). Surprisingly, while 25 μM AS applied to bacteria prior to the inoculations was ineffective, the same AS concentration applied as a pretreatment to the discs strongly increased the number of transformed cells in the target tissues and decreased the lag time for the appearance of the first GUS positive cells. NAA pretreatment on the basal side enhanced the AS effect. AS pretreatment was found both to advance the reentry of competent cells with a potential for cell division into the S phase of the cell cycle and to stimulate bacterial attachment to the cell walls. The relationship between transformation efficiency and DNA synthesis in the host cells is discussed. AS treatment of plant tissues prior to inoculation is proposed as a means of increasing the transformation rates.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01404037
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  • 28
    Digitale Medien
    Digitale Medien
    Rapid divergence of Agrobacterium vitis octopine-cucumopine Ti plasmids from a recent common ancestor (1993)
    Springer
    Molecular genetics and genomics 240 (1993), S. 49-57 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Microbial evolution ; RFLP analysis ; Ti plasmids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The octopine/cucumopine (o/c) Ti plasmids of the grapevine-associated Agrobacterium vitis strains constitute a family of related DNA molecules. Restriction maps were established of two limited-host-range o/c Ti plasmids, pTiAg57 and pTiAB3, and of the wide-host-range o/c Ti plasmid pTiHml. Together with the previously obtained map of the wide-host-range o/c Ti plasmid pTiTm4, about 1000 kb were mapped with a resolution of 0.2 kb, allowing a detailed comparison of the various structures. One region of the o/c Ti plasmids is highly conserved and differs mainly by the presence or absence of relatively small DNA fragments (0.9–2.7 kb); the other region has been modified more extensively and carries large sequences specific for each Ti plasmid type. The sequence similarity within large conserved regions shows that these plasmids have diverged recently and that their evolution was driven by large-scale genetic events rather than single nucleotide changes. These results have important implications for studies on bacterial evolution.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00276883
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  • 29
    Digitale Medien
    Digitale Medien
    Nopaline causes a conformational change in the NocR regulatory protein-nocR promoter complex of Agrobacterium tumefaciens Ti plasmid pTiT37 (1993)
    Springer
    Molecular genetics and genomics 241 (1993), S. 65-72 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Nopaline ; Gene regulation ; Protein-DNA interaction ; DNA topology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The nocR gene of Agrobacterium tumefaciens Ti plasmid pTiT37 is the regulatory gene of the nopaline catabolism (noc) operon of pTiT37. We have cloned and sequenced nocR, which encodes a DNA-binding protein. The deduced amino acid sequence is similar to those of members of the LysR family of prokaryotic activator proteins. Gel retardation experiments demonstrated that the NocR protein binds to the nocR promoter in both the presence and absence of nopaline. The increased mobility of the complex and alterations in the DNase I footprints revealed a nopaline-induced conformational change in the NocR-DNA complex. Sequence analysis of the NocR binding site indicated the presence immediately downstream of the −10 sequence of the nocR promoter of a 12 by putative operator overlapping a consensus gyrase recognition sequence and an 18 by long alternating purine-pyrimidine sequence. These results suggest that nopaline-induced alterations in the NocR protein-nocR promoter complex might control gene expression in the noc operon.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00280202
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  • 30
    Digitale Medien
    Digitale Medien
    A study of some factors affectingAgrobacterium transformation and plant regeneration ofDendranthema grandiflora Tzvelev (syn.Chrysanthemum morifolium Ramat.) (1993)
    Springer
    Plant cell, tissue and organ culture 33 (1993), S. 171-180 
    Details
    ISSN: 1573-5044
    Schlagwort(e): Agrobacterium ; Dendranthema grandiflora ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In an attempt to develop a system for producing transformed plants from explants ofDendranthema grandiflora, the susceptibility of the cultivar Super White to various wild-type strains ofAgrobacterium tumefaciens andA. rhizogenes was investigated. Tumour formation was not a reliable indicator of the ability of a related disarmed strain to mediate transformation. Following inoculation of explants with disarmedAgrobacterium strains, a number of shoots developed on selective media. However, none of these shoots were transformed. By co-cultivating stem internode explants with a mixed inoculum of wild-type and disarmed strains, it was possible to obtain a callus stably transformed withAgrobacterium carrying a disarmed T-DNA. Histological analysis of explants revealed that shoot regeneration initially occurred from the cells of the epidermis and subsequently from the cortex. However, the cells which were susceptible to T-DNA transfer were confined to the vascular tissue.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01983231
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  • 31
    Digitale Medien
    Digitale Medien
    The biotechnology of crop legumes (1993)
    Springer
    Euphytica 74 (1993), S. 165-185 
    Details
    ISSN: 1573-5060
    Schlagwort(e): transgenic legumes ; genetic engineering ; particle bombardment ; Agrobacterium ; direct DNA transfer ; crop legumes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The absence of variety-independent gene transfer methods for major agronomic species has, until now, limited the usefulness of recombinant DNA techniques to crop improvement programs. Until recently, only Solanaceous crops could be used to study fundamental and applied problems in plant sciences. During the past five years rapid advances in cell biology, in combination with the development of novel gene transfer methodology allowed utilization of the tools of plant molecular biology in conventional breeding programs. Cereal and leguminous species were considered to be recalcitrant to genetic manipulation. As a result of the development of direct DNA transfer methodology into organized tissue, we are now in a position to introduce any foreign gene into almost all of the major cereals and legumes. This can be achieved efficiently, often in a variety-independent fashion. The object of this review is to provide a comprehensive account of the state of the art in gene transfer for the cultivated leguminous crops. Important oilseed and feed species primarily in industrialized countries, as well as minor but equally important species for sustaining growth populations in developing countries will be examined. Advantages of the various gene transfer methods that were shown to be useful for specific crops, as well as limitations and problems associated with each crop and gene transfer method will be discussed. Data from field trials of transgenic legumes, where available, will be presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00040399
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  • 32
    Digitale Medien
    Digitale Medien
    Agrobacterium-mediated genetic transformation of oilseed Brassica campestris: Transformation frequency is strongly influenced by the mode of shoot regeneration (1992)
    Springer
    Plant cell reports 11 (1992), S. 506-513 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Genetic transformation ; Oilseed Brassica campestris ; Agrobacterium ; Shoot differentiation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Protocols were developed for efficient shoot regeneration from hypocotyl and cotyledon explants of oilseed Brassica campestris (brown sarson) cv. ‘Pusa Kalyani’. These were used for genetic transformation by an Agrobacterium based binary vector carrying neomycin phosphotransferase (npt) gene and β-glucuronidase (gus)-intron gene for plant cell specific expression. Transformed plants were recovered from hypocotyl explants at a frequency of 7–13%. Addition of silver nitrate markedly enhanced shoot regeneration in hypocotyl explants under non-selection conditions and was found to be an absolute requirement under selection conditions. Cotyledon explants, inspite of being more regenerative, proved to be highly refractory to transformation. Only two chimeric transformed shoots were obtained from more than 10,000 cotyledons treated with Agrobacterium. In hypocotyl explants, shoot regeneration occurred from the vascular parenchyma both with and without the intervention of callus phase. Only the shoot buds differentiating from callus tissue were positive for GUS activity. In cotyledons, shoot buds originated only directly from the vascular parenchyma, generally at a distance of about 450–625 μ from the cut surface. Such shoots were negative for GUS activity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00236266
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  • 33
    Digitale Medien
    Digitale Medien
    Auxin autonomy in cultured tobacco teratoma tissues transformed by an auxin-mutant strain of Agrobacterium tumefaciens (1992)
    Springer
    Planta 188 (1992), S. 123-128 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Auxin (tumor tissue) ; Compensation (tms genes) ; Nicotiana (cell transformation) ; tms genes ; Tumor morphology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have studied the mechanism of auxin autonomy in tobacco (Nicotiana tabacum L.) crowngall tissues transformed by the auxin-mutant (tms −) A66 strain of Agrobacterium tumefaciens. Normally, tms − tobacco tumor tissues require the formation of shoots to exhibit auxin-independent growth in culture. We have isolated from tms − tobacco cells several stable variants that are fully hormone-independent and grow rapidly as friable, unorganized tissues, thus mimicking the growth and morphology of tms + tobacco cells that produce high levels of auxin. However, none of the variants contained the high levels of auxin found in tms + tumor cells. The variants could be divided into two classes with respect to their response to applied auxin. The first class was highly sensitive to applied auxin: low concentrations (1 μM) of α-naphthaleneacetic acid (NAA) severely inhibited growth and markedly stimulated the accumulation of the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC). The second class of variants showed a low sensitivity to applied auxin: growth was promoted by concentrations of NAA up to 10 μM, and growth inhibition and high ACC levels were observed only at high NAA concentrations (100 μM). Unorganized variants with low auxin sensitivity were also isolated from a variant line with high auxin sensitivity. The isolation of tumor cells that exhibited the growth phenotype of tms + cells while retaining the low auxin content and low auxin sensitivity of tms − cells indicates that full hormone autonomy, characteristic of wild-type crown-gall tumors, can be achieved by a mechanism that is independent of changes in the auxin physiology of the cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00198948
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  • 34
    Digitale Medien
    Digitale Medien
    Auxin autonomy in cultured tobacco teratoma tissues transformed by an auxin-mutant strain ofAgrobacterium tumefaciens (1992)
    Springer
    Planta 188 (1992), S. 123-128 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Auxin (tumor tissue) ; Compensation (tms genes) ; Nicotiana (cell transformation) ; tms genes ; Tumor morphology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have studied the mechanism of auxin autonomy in tobacco (Nicotiana tabacum L.) crowngall tissues transformed by the auxin-mutant (tms −) A66 strain ofAgrobacterium tumefaciens. Normally,tms − tobacco tumor tissues require the formation of shoots to exhibit auxin-independent growth in culture. We have isolated fromtms − tobacco cells several stable variants that are fully hormone-independent and grow rapidly as friable, unorganized tissues, thus mimicking the growth and morphology oftms + tobacco cells that produce high levels of auxin. However, none of the variants contained the high levels of auxin found intms + tumor cells. The variants could be divided into two classes with respect to their response to applied auxin. The first class was highly sensitive to applied auxin: low concentrations (1 μM) of α-naphthaleneacetic acid (NAA) severely inhibited growth and markedly stimulated the accumulation of the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid (ACC). The second class of variants showed a low sensitivity to applied auxin: growth was promoted by concentrations of NAA up to 10 μM, and growth inhibition and high ACC levels were observed only at high NAA concentrations (100 μM). Unorganized variants with low auxin sensitivity were also isolated from a variant line with high auxin sensitivity. The isolation of tumor cells that exhibited the growth phenotype oftms + cells while retaining the low auxin content and low auxin sensitivity oftms − cells indicates that full hormone autonomy, characteristic of wild-type crown-gall tumors, can be achieved by a mechanism that is independent of changes in the auxin physiology of the cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01160721
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  • 35
    Digitale Medien
    Digitale Medien
    Characterization of competent cells and early events of Agrobacterium-mediated genetic transformation in Arabidopsis thaliana (1992)
    Springer
    Planta 188 (1992), S. 439-456 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Arabidopsis ; Cotyledon ; Root explant (in vitro culture) ; Transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The insertion of foreign DNA in plants occurs through a complex interaction between Agrobacteria and host plant cells. The marker gene β-glucuronidase of Escherichia coli and cytological methods were used to characterize competent cells for Agrobacterium-mediated transformation, to study early cellular events of transformation, and to identify the potential host-cell barriers that limit transformation in Arabidopsis thaliana L. Heynh. In cotyledon and leaf explants, competent cells were mesophyll cells that were dedifferentiating, a process induced by wounding and-or phytohormones. The cells were located either at the cut surface or within the explant after phytohormone pretreatment. In root explants, competent cells were present in dedifferentiating pericycle, and were produced only after phytohormone pretreatment. Irrespective of their origin, the competent cells were small, isodiametric with thin primary cell walls, small and multiple vacuoles, prominent nuclei and dense cytoplasm. In both cotyledon and root explants, histological enumeration and β-glucuronidase assays showed that the number of putatively competent cells was increased by preculture treatment, indicating that cell activation and cell division following wounding were insufficient for transformation without phytohormone treatment. Exposure of explants for 48 h to A. tumefaciens produced no characteristic stress response nor any gradual loss of viability nor cell death. However, in the competent cell, association between the polysaccharide of the host cell wall and that of the bacterial filament was frequently observed, indicating that transformation required polysaccharide-to-polysaccharide contact. Flow cytofluorometry and histological analysis showed that abundant transformation required not only cell activation (an early state exhibiting an increase in nuclear protein) but also cell proliferation (which in cotyledon tissue occurred at many ploidy levels). Noncompetent cells could be made competent with the appropriate phytohormone treatments before bacterial infection: this should aid analysis of critical steps in transformation procedures and should facilitate developing new strategies to transform recalcitrant plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00192812
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  • 36
    Digitale Medien
    Digitale Medien
    Agrobacterium-mediated transformation of tomatillo (Physalis ixocarpa) and tissue specific and developmental expression of the CaMV 35S promoter in transgenic tomatillo plants (1992)
    Springer
    Plant cell reports 11 (1992), S. 558-562 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Agrobacterium ; Plant Transformation ; Gene Expression ; CaMV 35S Promoter ; Physalis ixocarpa
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A protocol for the Agrobacterium-mediated transformation of tomatillo was developed. Up to 40 transgenic plants could be obtained in experiments using 60 cotyledon expiants. The transformed nature of the regenerated plants was confirmed by NPT II and Southern blot hybridization analysis. Using the b-glucuronidase system the tissue specific and developmental patterns of expression of the Cauliflower Mosaic Virus 35S promoter were determined in transgenic tomatillo plants. It was found that this promoter is developmentally regulated during fruit and seed formation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00233092
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  • 37
    Digitale Medien
    Digitale Medien
    Efficient transformation of Arabidopsis thaliana: comparison of the efficiencies with various organs, plant ecotypes and Agrobacterium strains (1992)
    Springer
    Plant cell reports 12 (1992), S. 7-11 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Arabidopsis thaliana ; Transformation ; Agrobacterium ; T-DNA ; Shoot regeneration ; Transgenic plant
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The efficiency of Agrobacterium-mediated transformation of Arabidopsis thaliana was compared with different organs, Arabidopsis ecotypes, and Agrobacterium strains. Efficiency of shoot regeneration was examined using hypocotyl, cotyledon and root explants prepared from young seedlings. Hypocotyl expiants had the highest regeneration efficiency in all of the four Arabidopsis ecotypes tested, when based on a tissue culture system of callus-inducing medium (CIM: Valvekens et al. 1988) and shoot-inducing medium (SIM: Feldmann and Marks 1986). Histochemical analysis using the ß-glucuronidase (GUS) reporter gene showed that the gusA gene expression increased as the period of preincubation on CIM was extended, suggesting that dividing cells are susceptible to Agrobacterium infection. In order to obtain transgenic shoots, hypocotyl explants preincubated for 7 or 8 days on CIM were infected with Agrobacterium containing a binary vector which carries two drug-resistant genes as selection markers, and transferred to SIM for selection of transformed shoots. Of four Arabidopsis ecotypes and of three Agrobacterium strains examined, Wassilewskija ecotype and EHA101 strain showed the highest efficiency of regeneration of transformed shoots. By combining the most efficient factors of preincubation period, Arabidopsis ecotype, tissue, and bacterial strain, we obtained a transformation efficiency of about 80–90%. Southern analysis of 124 transgenic plants showed that 44% had one copy of inserted T-DNA while the others had more than one copy.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00232413
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  • 38
    Digitale Medien
    Digitale Medien
    Translation controls the expression level of a chimaeric reporter gene (1992)
    Springer
    Plant molecular biology 20 (1992), S. 921-938 
    Details
    ISSN: 1573-5028
    Schlagwort(e): β-D-glucuronidase ; mannopine synthase promoter ; Agrobacterium ; gene expression ; initiation of translation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Transcriptional and translational fusions between the reading frame of the β-D-glucuronidase gene (gusA) and the 2′ as well as the 1′ promoter of mannopine synthase (mas), a TR locus of Agrobacterium tumefaciens, were made. The expression of these constructs was studied in the transgenic F1 offspring of independent tobacco transformants at the protein level by assaying for GUS activity and western blot analysis of the GUS protein and at the steady-state mRNA level. In leaves, stems and roots no correlation was found between steady-state levels of GUS mRNA and enzyme activity. In older tissues significantly higher GUS activities were found. This is explained by the stable character of the GUS protein together with an accumulation of protein upon ageing. Three to ten times higher GUS activities were found for in vitro grown plants than for greenhouse-grown plants of the same offspring, despite similar levels of GUS mRNA. Roots from in vitro grown plants display three to ten times higher GUS activities than stems and leaves. In transgenic plants grown in vitro, containing a translational fusion with two AUGs in phase, the initiation of translation in leaf material occurred at both AUGs. Initiation of translation at the first AUG, however, was ten times more frequent. In contrast, initiation in roots from in vitro grown plants occurred exclusively at the second AUG.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00027163
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  • 39
    Digitale Medien
    Digitale Medien
    Factors influencing Agrobacterium-mediated transient expression of gusA in rice (1992)
    Springer
    Plant molecular biology 20 (1992), S. 1037-1048 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; rice ; transformation ; Ti plasmid ; GUS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Transient expression of GUS in rice (Oryza sativa L.) mediated by Agrobacterium tumefaciens was characterized using binary vectors containing gusA genes that express minimal (pKIWI105 and pCNL1) or no (p35S-GUS-INT and pCNL56) GUS activity in bacteria. Four-day old seedlings obtained from seeds or immature embryos of rice were cut into shoot, root, and seed remnants and inoculated with various strains of A. tumefaciens. Transient GUS expression events were quantitated histochemically by determining the frequency of explants exhibiting blue spots indicative of GUS at four to six days after cocultivation with A. tumefaciens. A. tumefaciens strains that did not contain the gusA gene (At643) or a Ti-plasmid (At563 and At657) did not elicit any blue staining characteristic of GUS activity. Several parameters were important in obtaining efficient transient expression of GUS in rice mediated by A. tumefaciens. The growth regulator 2,4-D inhibited GUS expression if present during the seed germination period, but the presence of 6 mg/1 2,4-D during cocultivation of the explants with A. tumefaciens slightly enhanced GUS expression efficiency. All 21 rice cultivars tested expressed GUS after co-cultivation with A. tumefaciens. The GUS expression frequency was highest amongst the indica cultivars. The frequencies of GUS expression in japonica cultivars and in Oryza glaberrima cultivars (grown primarily in Africa) were generally one-half to one-third the level found for indica varieties. Leaf explants were more susceptible to A. tumefaciens-facilitated GUS expression than were roots or seed remnants. The vir genes of an agropine-type Ti-plasmid of A. tumefaciens were most effective in directing transient GUS expression in rice, whereas those of a nopaline-type and an octopine-type plasmid were less effective. We have also found that the frequency of transient expression of GUS was higher with pBIN19 as the precursor cloning vector than with pEND4K as the precursor cloning vector. Reasons for differences in effectiveness of these binary vectors are discussed. Using the conditions described here, A. tumefaciens-mediated frequencies of transient GUS expression in four-day old shoots of several rice cultivars were routinely in excess of 50%.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00028891
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  • 40
    Digitale Medien
    Digitale Medien
    A versatile binary vector system with a T-DNA organisational structure conducive to efficient integration of cloned DNA into the plant genome (1992)
    Springer
    Plant molecular biology 20 (1992), S. 1203-1207 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; binary vector ; CaMV 35S ; gene expression ; β-glucuronidase ; Nicotiana plumbaginifolia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A versatile gene expression cartridge and binary vector system was constructed for use in Agrobacterium-mediated plant transformation. The expression cartridge of the primary cloning vector, pART7, comprises of cauliflower mosaic virus Cabb B-JI isolate 35S promoter, a multiple cloning site and the transcriptional termination region of the octopine synthase gene. The entire cartridge can be removed from pART7 as a Not I fragment and introduced directly into the binary vector, pART27, recombinants being selected by blue/white screening for β-galactosidase. pART27 carries the RK2 minimal replicon for maintenance in Agrobacterium, the ColE1 origin of replication for high-copy maintenance in Escherichia coli and the Tn7 spectinomycin/streptomycin resistance gene as a bacterial selectable marker. The organisational structure of the T-DNA of pART27 has been constructed taking into account the right to left border, 5′ to 3′ model of T-DNA transfer. The T-DNA carries the chimaeric kanamycin resistance gene (nopaline synthase promoter-neomycin phosphotransferase-nopaline synthase terminator) distal to the right border relative to the lacZ′ region. Utilisation of these vectors in Agrobacterium-mediated transformation of tobacco demonstrated efficient T-DNA transfer to the plant genome.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00028910
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  • 41
    Digitale Medien
    Digitale Medien
    Multiple ocs-like elements required for efficient transcription of the mannopine synthase gene of T-DNA in maize protoplasts (1992)
    Springer
    Plant molecular biology 20 (1992), S. 219-233 
    Details
    ISSN: 1573-5028
    Schlagwort(e): promoter ; electroporation ; protoplasts ; transient assay ; Agrobacterium ; Ti plasmid ; Zea mays
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Regulatory elements controlling transcriptional activity of the mannopine synthase 2′ promoter (mas 2′) were defined by analysis of deletion mutants in transient expression assays in maize protoplasts. Deletion of the region between −305 and −290 containing sequence similarity to the octopine synthase (ocs) promoter element reduced activity by 67% compared to wild type activity. Less than 1% of the activity remained in 5′ deletions downstream of −153. Inclusion of various heterologous enhancer-like sequences immediately upstream of position −325 increased activity by up to 7.5-fold. Insertion of the −325 to −275 sequence alone, or in combination with heterologous enhancer-like elements, restored activity of some of the 5′-deletion mutants. Restoration of activity was not obtained with mutants deleted past position −127. Our results suggest that a single class of nuclear proteins from maize interact with high affinity at elements designated mas b (−306 to −275; mas 1′ element), d (−127 to −108), and e (−82 to −39; mas 2′ element) as well as the 20 bp element from the ocs promoter. Although the binding site at mas d only appears to accommodate a single protein, this element has the potential to make a weak, but positive, contribution to the activity of the mas 2′ promoter. The binding of nuclear proteins could not be demonstrated at mas a and c, both of which showed limited homology to the ocs element. Mutational evidence suggested that mas a and c may also contribute to mas 2′ transcription.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00014490
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  • 42
    Digitale Medien
    Digitale Medien
    Expression of a chimaeric heat-shock-inducible Agrobacterium 6b oncogene in Nicotiana rustica (1992)
    Springer
    Plant molecular biology 18 (1992), S. 921-930 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; 6b gene ; oncogenes ; tumour induction ; wound-induced cell division
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The T-6b gene of Agrobacterium tumefaciens strain Tm4 induces tumours on Nicotiana rustica by an as yet unknown mechanism. These tumours cannot be regenerated into normal plants. To study the effect of the T-6b gene product on normal plant cells, the T-6b gene was placed under control of the Drosophila melanogaster hsp70 heat-shock promoter and introduced into N. rustica. Progeny of an hsp70-T-6b transformant developed into normal plants. The inducibility of the hsp70-T-6b construct was shown by northern analysis and by heat-shock-dependent growth alterations on the level of whole seedlings. Upon wounding at normal temperature conditions hsp70-T-6b plants formed small tumours on leaves and stems. Grafts between transformed plants and normal plants led to a wound callus which remained limited to transformed tissues, indicating that the T-6b gene product does not diffuse. Protoplasts of hsp70-T-6b plants divided in the same way as control protoplasts under standard culture conditions. However, when protoplast cultures were started in the absence of hormones, normal cells rapidly lost their sensitivity towards hormones, whereas hsp70-T-6b cells remained sensitive for a significantly longer period. Thus, the T-6b gene product alters hormone sensitivity during the initial phases of protoplast culture.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00019206
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  • 43
    Digitale Medien
    Digitale Medien
    Organization and functional analysis of three T-DNAs from the vitopine Ti plasmid pTiS4 (1992)
    Springer
    Molecular genetics and genomics 235 (1992), S. 292-303 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Ti plasmid ; T-DNA ; Vitopine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The vitopine Ti plasmid pTiS4 of Agrobacterium vitis has an unusual T-DNA organization. The pTiS4 oncogenes, localized by screening selected pTiS4 clones for growth-inducing activity, are localized on three T-DNAs, whereas in all other characterized Ti plasmids one or two T-DNAs are found. The nucleotide sequences and predicted amino acid sequences of the pTiS4 oncogenes set them apart from the corresponding genes from other Ti or Ri plasmids. The oncogenes induce the same type of reaction on various test plants as the well-known pTiAch5 oncogenes but the pTiS4 ipt gene induces considerably more shoots than its Ach5 homologue. We have also identified the gene coding for vitopine synthase as well as a vitopine synthase pseudogene. Both sequences show homology to the octopine synthase gene. In terms of both nucleotide sequence and overall organization, the pTiS4 T-DNAs appear to be only distantly related to previously characterized T-DNAs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00279373
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  • 44
    Digitale Medien
    Digitale Medien
    The region essential for efficient autonomous replication of pSa in Escherichia coli (1992)
    Springer
    Molecular genetics and genomics 235 (1992), S. 55-63 
    Details
    ISSN: 1617-4623
    Schlagwort(e): RepA protein ; Agrobacterium ; recombination ; Recombinase ; Interons
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Comparative analyses were made between plasmid pSa17, a deletion derivative of pSa that is capable of replicating efficiently in Escherichia coli and plasmid pSa3, a derivative that is defective for replication. By comparing the restriction maps of these two derivatives, the regions essential for replication and for stable maintenance of the plasmid were determined. A 2.5 kb DNA segment bearing the origin of DNA replication of pSa17 was sequenced. A 36 kDa RepA protein was encoded in the region essential for replication. Downstream of the RepA coding region was a characteristic sequence including six 17 bp direct repeats, the possible binding sites of RepA protein, followed by AT-rich and GC-rich sequences. Furthermore, an 8 bp incomplete copy of the 17 bp repeat was found in the promoter region of the repA gene. Based on the hypothesis that RepA protein binds to this partial sequence as well as to intact 17 bp sequences, an autoregulatory system for the synthesis of RepA protein may be operative. Another open reading frame (ORF) was found in the region required for the stability of the plasmid. The putative protein encoded in this ORF showed significant homology to several site-specific recombination proteins. A possible role of this putative protein in stable maintenance of the plasmid is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00286181
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  • 45
    Digitale Medien
    Digitale Medien
    Enhanced stable expression of aVibrio luciferase under the control of the Ω-translational enhancer in transgenic plants (1992)
    Springer
    World journal of microbiology and biotechnology 8 (1992), S. 638-644 
    Details
    ISSN: 1573-0972
    Schlagwort(e): Agrobacterium ; bioluminescence ; high-copyvir vector ; high-efficiency protein production ; high-efficiency transformation of plants ; T-vectors ; Vibrio fischeri ; Vibrio harveyi
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Abstract A fusion gene usingluxA andluxB genes ofVibrio species has been designed to express light autonomously in plants.LuxA:luxB was introduced into plants by a high-efficiency transformation system consisting of a high-copy virulence helper plasmid pUCD2614 and T-vector pUCD2715 containingluxA:luxB. The expression ofluxA:luxB fusion gene was optimized by adjusting the spacing between the genes and by placing the translational efficiency of its mRNA under the control of the Ω-3 translational enhancer. The resulting transgenic plants synthesized luciferase at levels greater than 1% of the total leaf protein. These plants produced light autonomously and light intensity was enhanced by the addition of aldehyde. That theluxA:luxB fusion has been optimized enables its use as a reporter for gene activity in plants during development and under various stress-inducing conditions. These results show that a specific protein from an introduced foreign gene can be produced with high efficiency in cultivated plants and such a system is therefore amenable for production of desired proteins through conventional farming methods.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01238805
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  • 46
    Digitale Medien
    Digitale Medien
    Agrobacterium-mediated transformation of pepino and regeneration of transgenic plants (1991)
    Springer
    Plant cell reports 10 (1991), S. 208-212 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Agrobacterium ; mediated transformation ; Pepino ; pKIWI110 ; Regeneration ; Solanum muricatum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Regeneration of pepino (Solanum muricatum Ait.) shoots was achieved both by organogenesis and by embryogenesis. Shoots derived via organogenesis were easily rooted and most regenerated plants appeared phenotypically normal. Transgenic plants were obtained using the binary vector pKIWI110 in the avirulent Agrobacterium tumefaciens strain LBA4404. Optimization of transformation protocols was rapidly achieved by monitoring early expression of the GUS (β-D-glucuronidase) reporter gene carried on pKIWI110. Transgenic plants expressed GUS and selectable marker genes for kanamycin resistance and chlorsulfuron resistance. PCR (polymerase chain reaction) and Southern analysis provided molecular evidence for transformation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00234297
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  • 47
    Digitale Medien
    Digitale Medien
    Genetic transformation of Chrysanthemum using wild type Agrobacterium strains; strain and cultivar specificity (1991)
    Springer
    Plant cell reports 9 (1991), S. 505-508 
    Details
    ISSN: 1432-203X
    Schlagwort(e): Agrobacterium ; Tumour induction ; Dendranthema grandiflora ; Polymerase chain reaction ; ß-Glucuronidase ; Neomycine phosphotransferase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary To develop an Agrobacterium mediated transformation protocol for chrysanthemum we studied the transformation efficiency of commonly used A.tumefaciens strains on 14 genotypes by comparing tumour size and frequency. One genotype was analyzed in detail using 14 strains of both A.tumefaciens and A.rhizogenes. Only a few genotype/strain combinations resulted in significant tumour formation. Especially 0-type strains were highly efficient. An 0-type strain was used to transfer genes for neomycine phosphotransferase (NPT II) and ß-glucuronidase (GUS) to a susceptible cultivar. Transfer of the GUS gene was confirmed by using the Polymerase Chain Reaction (PCR).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00232106
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  • 48
    Digitale Medien
    Digitale Medien
    35S-β-glucuronidase gene blocks biological effects of cotransferred iaa genes (1991)
    Springer
    Plant molecular biology 16 (1991), S. 853-864 
    Details
    ISSN: 1573-5028
    Schlagwort(e): GUS ; UidA ; 35S promoter ; Agrobacterium ; plant cell transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The iaaM and iaaH genes of Agrobacterium tumefaciens and Agrobacterium rhizogenes play an important role in crown gall and hairy root disease. The iaaM gene codes for tryptophan monooxygenase which converts tryptophan into indole-3-acetamide (IAM). IAM is converted into the auxin indole-3-acetic acid (IAA) by indoleacetamide hydrolase, encoded by the iaaH gene. In functional studies on the activity of the iaa genes of the TB region of the A. tumefaciens biotype III strain Tm4, the frequently used 35S-β-glucuronidase (35S-UidA or GUS) marker gene was found to inhibit IAA synthesis and root induction encoded by the TB iaa genes. To exert this inhibition, the 35S-UidA gene must be cotransferred with the iaaH gene. The 35S promoter alone is sufficient to cause the inhibitory effect.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00015077
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  • 49
    Digitale Medien
    Digitale Medien
    Detection of gene regulatory signals in plants revealed by T-DNA-mediated fusions (1991)
    Springer
    Plant molecular biology 17 (1991), S. 837-851 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; binary vector ; gene fusion ; β-glucuronidase ; T-DNA insertion ; transgenic tobacco
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A binary vector, pPRF120, was designed to detect T-DNA insertions within transcriptionlly active areas of the plant genome. Linked to the right-border repeat, the vector contains a promoterless β-glucuronidase (GUS) gene which can, upon integration into chromosomes, be activated by cis-acting regulatory elements. The vector also incorporates a chimeric marker gene conferring resistance to kanamycin to ensure recovery of gene fusions regardless of the extent of their tissue-specific or developmentally regulated expression, and to permit analysis of the frequency of plants which express the promoterless reporter. Approximately 1000 transgenic tobacco plants harboring pPRF120 were regenerated. Analysis of 52 individuals indicated that more than 80% contain single, intact copies of the T-DNA, regardless of their ability to express the promoterless GUS gene. Screening of leaf tissue from the 1000 pPRF120 transformants revealed that ca. 5% of the plants contained GUS activity. Fluorogenic and histological GUS assays were used to visualize and quantify tissue- and cell-specific gene expression. The potential usefulness of pPRF120 in comparison to other vectors designed to generate in vivo gene fusions is discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00037065
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  • 50
    Digitale Medien
    Digitale Medien
    Environmental conditions differentially affect vir gene induction in different Agrobacterium strains. Role of the VirA sensor protein (1991)
    Springer
    Plant molecular biology 16 (1991), S. 1051-1059 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; virulence gene ; VirA protein ; gene regulation ; sensor protein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The induction of vir gene expression in different types of Agrobacterium strains shows different pH sensitivity profiles. The pH sensitivity pattern demonstrated by octopine Ti strains was similar to that of a supervirulent leucinopine Ti strain, whereas this was different from that shown by nopaline Ti strains and agropine Ri strains. Data are given which indicate that these differences are due to different properties of the virA genes of these wild types. An exceptional case was formed by strains with the limited-host-range plasmid pTiAG57 which showed AS-dependent vir induction only if reduced inoculum sizes were used and the temperature was 28°C or below.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00016076
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  • 51
    Digitale Medien
    Digitale Medien
    An alternative approach for gene transfer in trees using wild-typeAgrobacterium strains (1991)
    Springer
    Plant molecular biology 17 (1991), S. 441-452 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; crown gall ; poplar ; tree transformation ; wild cherry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Micropropagated shoots of three forest tree species, poplar (Populus tremula × P.alba), wild cherry (Prunus avium L.) and walnut (Juglans nigra × J. regia), were inoculated each with six different wild-typeAgrobacterium strains. Poplar and wild cherry developed tumors that grew hormone-independently, whereas on walnut, gall formation was weak. On poplar and wild cherry, tumors induced by nopaline strains developed spontaneously shoots that had a normal phenotype and did not carry oncogenic T-DNA. From these observations, we have established a co-inoculation method to transform plants, using poplar as an experimental model. The method is based on inoculation of stem internodes with anAgrobacterium suspension containing both an oncogenic strain that induces shoot differentiation and a disarmed strain that provides the suitable genes in a binary vector. We used the vector pBI121 carryingneo (kanamycin resistance) anduidA (β-glucuronidase) genes to facilitate early selection and screening. Poplar plants derived from kanamycin-resistant shoots that did not carry oncogenic T-DNA, were shown to contain and to expressneo anduidA genes. These results suggest that wild-typeAgrobacterium strains that induce shoot formation directly from tumors can be used as a general tool for gene transfer, avoiding difficult regeneration procedures.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00040638
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  • 52
    Digitale Medien
    Digitale Medien
    Pea lectin is correctly processed, stable and active in leaves of transgenic potato plants (1991)
    Springer
    Plant molecular biology 17 (1991), S. 89-100 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; haemagglutination ; lectin (Pisum) ; protein processing ; transgenic potato
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A gene encoding the preproprotein of the pea (Pisum sativum) lectin was expressed in transgenic potato plants using a cauliflower mosaic virus (CaMV) 35S promoter or a tobacco ribulose bisphosphate carboxylase small subunit (ssRubisco) promoter. Presence of the pea lectin to levels greater than 1% of total soluble leaf protein was detected by radioimmunoassay (RIA). The pattern of expression derived from the two promoters was established using both RIA and a squash-blot immunolocalisation technique. Western blotting demonstrated that the preproprotein was correctly processed, generating α and β subunits that assembled to give an isolectin form observed in pea seeds and roots. It was also found that the haemagglutination activity and specificity of pea lectin synthesised in transgenic potato leaves was comparable to purified lectin from pea cotyledons.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00036809
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  • 53
    Digitale Medien
    Digitale Medien
    Cross-talk between the virulence and phosphate regulons of Agrobacterium tumefaciens caused by an unusual interaction of the transcriptional activator with a regulatory DNA element (1991)
    Springer
    Molecular genetics and genomics 227 (1991), S. 385-390 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Cis-acting DNA element ; Cross-talk ; DNA-protein interaction ; Positive regulator
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Transcription of a virulence gene on the hairyroot-inducing plasmid A4, which is induced by plant factors in Agrobacterium tumefaciens, was also activated by phosphate limitation in both A. tumefaciens and Escherichia coli. The starting site of RNA synthesized under the two inducing conditions was the same, and an identical promoter was responsible for both inducible expressions. The response of the virulence gene to phosphate limitation did not require the positive regulator VirG for the virulence regulon, but depended entirely on the presence of PhoB protein, the positive regulator for the phosphate regulon. The DNA signal upstream of the virulence gene, which is targeted by the VirG protein, was recognized by the E. coli PhoB protein in vitro. These results indicate that cross-talk between the two regulons occurred during the recognition of a DNA signal by the regulatory protein.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00273927
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  • 54
    Digitale Medien
    Digitale Medien
    Characterization of the supervirulent virG gene of the Agrobacterium tumefaciens plasmid pTiBo542 (1991)
    Springer
    Molecular genetics and genomics 230 (1991), S. 302-309 
    Details
    ISSN: 1617-4623
    Schlagwort(e): VirG ; Agrobacterium ; vir activation ; Supervirulence ; pTiBo542
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The virG gene of the Agrobacterium tumefaciens Ti plasmid pTiBo542 has previously been reported to elicit stronger vir gene expression than its counterpart in the pTiA6 plasmid, a property we call the “superactivator” phenotype. The DNA sequence of the pTiBo542 virG gene was determined and compared to that of the pTiA6 gene. The DNA sequences of these genes differ at 16 positions: two differences are in the promoter regions, 12 are in the coding regions, and two are in the 3′ untranslated regions. The 3′ end of the pTiA6 virG gene also contains a probable insertion sequence that is not found downstream of the pTiBo542 gene. The base pair differences in the two coding regions result in only two amino acid differences, both in the amino-terminal halves of the proteins. Five hybrid virG genes were constructed and used to activate the expression of a virB::lacZ gene fusion. Differences in the coding regions of these genes accounted for most of the superactivator phenotype, while differences at the promoter and 3′ untranslated regions also contributed. These findings suggest that the properties of these VirG proteins and their quantities are important for vir gene induction, and also suggest a long-term selective pressure for mutations contributing to differences between these two genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00290681
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  • 55
    Digitale Medien
    Digitale Medien
    Mapping of the ros virulence regulatory gene of A. tumefaciens (1991)
    Springer
    Molecular genetics and genomics 230 (1991), S. 24-27 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Ti plasmid ; Tn5mob ; Chromosome ; Repressor
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Virulence functions associated with the oncogenicity of Agrobacterium tumefaciens are encoded by vir genes contained in six major operons located on the Ti plasmid. The virC and virD operons encode functions responsible for host range and T-intermediate processing. These two operons are regulated positively by the product of virG and negatively by the product of the chromosomal gene ros, which encodes a 15.5 kDa repressor. To determine the location of the ros gene we have constructed A. tumefaciens HFR strains, using transposon Tn5mob to mobilize the ros locus, and used them to map the location of ros relative to auxotrophic loci. Tight linkage was found between ros, his-34 and his-19. A linkage map is presented showing the location of ros relative to other known chromosomal genes associated with virulence functions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00290645
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  • 56
    Digitale Medien
    Digitale Medien
    Regeneration and transformation of Ribes (1991)
    Springer
    Plant cell, tissue and organ culture 24 (1991), S. 91-95 
    Details
    ISSN: 1573-5044
    Schlagwort(e): Agrobacterium ; regeneration ; Ribes nigrum ; tissue culture ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Transformation of the black currant cv. Ben More was achieved by utilising the binary vector system of Agrobacterium tumefaciens. This system involved the inoculation of peeled internodal stem segments with A. tumefaciens strain LBA4404 containing the binary vector PBI121.X with the marker genes Betaglucuronidase (GUS) and neomycin phosphotransferase II (NPTII). Shoot regeneration occurred on nutrient media based on M&S salts. Transformation was confirmed by the fluorogenic assay procedure which determined that the GUS gene had been transferred into the plant material and was being expressed. Concurrent transfer of the NPTII gene into the plant material was also confirmed with a ‘dot blot’ assay on selected GUS positive plantlets.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00039736
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  • 57
    Digitale Medien
    Digitale Medien
    Transformation of Nicotiana tabacum, N. debneyi, and N. rustica: Inheritance and protoplast expression of antibiotic resistance (1991)
    Springer
    Plant cell, tissue and organ culture 25 (1991), S. 189-197 
    Details
    ISSN: 1573-5044
    Schlagwort(e): Agrobacterium ; leaf explant ; mesophyll protoplast ; regeneration ; selective agent ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Agrobacterium tumefaciens strains harbouring plasmid vectors pBCAT1, pVU1011 or pMON806 were used to transform leaf explants of Nicotiana tabacum cultivars ‘Delgold’ and ‘Candel’, N. debneyi, and N. rustica var. NRT. Transgenic plants resistant to the selective agents kanamycin, hygromycin or methotrexate were regenerated and used as sources of leaf mesophyll protoplasts. Protoplasts divided and regenerated plants in the presence of selective agents at levels inhibitory to protoplasts of non-transformed plants. Cross-resistance of protoplasts to more than one selective agent was not observed in this study which suggests that this approach may lead to an efficient interspecific somatic hybrid selection system.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00036210
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  • 58
    Digitale Medien
    Digitale Medien
    A novel assay for genetic and environmental changes in the architecture of intact root systems of plants grown in vitro (1991)
    Springer
    Plant cell, tissue and organ culture 27 (1991), S. 129-139 
    Details
    ISSN: 1573-5044
    Schlagwort(e): Agrobacterium ; auxins ; cytokinins ; roots ; Solanum tuberosum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A novel and versatile in vitro assay system is presented which has considerable scope for accurate description of environmentally and/or genetically induced changes in the architecture of intact plant root systems. Use of the assay system is exemplified by the analysis of potato plants with visibly distinct root systems. These were obtained by growth of normal and transgenic potato plants, transformed with Agrobacterium Tcyt and rol genes on standard culture medium and on media supplemented with NAA and zeatin. Consequences for parameters such as root weight, root length, percentage secondary roots and root density distribution with depth were quantified. The logarithmic regression: log10(ϱ)=A+Bd, in which ϱ is the root density (root weight per media volume) at depth d, proved useful in quantifying the decline of root density with depth by the single slope parameter B. From the calculated relations for the various root systems, and their root weights, profiles of their comparable root weight distributions were drawn. A number of features and drawbacks, and possible uses of the assay system are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00041281
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  • 59
    Digitale Medien
    Digitale Medien
    Glyphosate degradation byAgrobacterium radiobacter isolated from activated sludge (1990)
    Springer
    Journal of industrial microbiology and biotechnology 6 (1990), S. 219-221 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Agrobacterium ; Achromobacter ; Glyphosate degradation ; Biodegradation ; Sequencing batch reactor ; Activated sludge
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Two species of bacteria capable of growth onN-phosphonomethylglycine (glyphosate) were isolated from a bench scale sequencing batch reactor degrading a waste stream containing glyphosate. The enrichment and isolation medium contained defined salts and glyphosate as the sole carbon and energy source. Glyphosate was stoichiometrically degraded to aminomethylphosphonic acid (AMPA). The bacteria have been identified asAgrobacterium radiobacter andAchromobacter Group V D.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01577700
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  • 60
    Digitale Medien
    Digitale Medien
    3-Fluorobenzoate enriched bacterial strain FLB 300 degrades benzoate and all three isomeric monofluorobenzoates (1990)
    Springer
    Archives of microbiology 153 (1990), S. 193-199 
    Details
    ISSN: 1432-072X
    Schlagwort(e): 3-Fluorobenzoate ; 4-Fluorocatechol ; Orthopathway ; Chemotaxonomy ; rRNA analysis ; Quinone pattern analysis ; Polyamine pattern analysis ; Agrobacterium ; Rhizobium branch
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The bacterial strain FLB300 was enriched with 3-fluorobenzoate as sole carbon source. Besides benzoate all isomeric monofluorobenzoates were utilized. Regioselective 1,2-dioxygenation rather than 1,6-dioxygenation yielded 4-fluorocatechol and minimized the production of toxic 3-fluorocatechol. Degradation of 4-fluorocatechol was mediated by reactions of ortho cleavage pathway activities. Chemotaxonomic and r-RNA data excluded strain FLB300 from a phylogenetically defined genus Pseudomonas and suggested its allocation to the alpha-2 subclass of Proteobacteria in a new genus of the Agrobacterium-Rhizobium branch.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00247820
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  • 61
    Digitale Medien
    Digitale Medien
    T-DNA presence and opine production in tumors of Picea abies (L.) Karst induced by Agrobacterium tumefaciens A281 (1990)
    Springer
    Plant molecular biology 14 (1990), S. 111-117 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; conifers ; DNA hybridization ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The hypervirulent Agrobacterium tumefaciens strain A281 formed frequent tumors (31%) on Picea abies (Norway spruce), an economically important tree species in Swedish forests. Three-month-old seedlings were inoculated and tumors were established that grew hormone-independently in culture. Tumors contained agropine and mannopine/mannopinic acid as determined by acid pH paper electrophoresis. In addition, DNA hybridization studies showed that the DNA from these tumor lines contained sequences homologous to Ti plasmid T-DNA, whereas wild-type spruce seedling DNA did not. These results suggest that Agrobacterium vectors can be used for gene transfer into this important forest species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00018552
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  • 62
    Digitale Medien
    Digitale Medien
    Improved binary vectors for Agrobacterium-mediated plant transformation (1990)
    Springer
    Plant molecular biology 14 (1990), S. 269-276 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; binary vectors ; ColE1 replicon ; lac Z′ ; pRi replicon ; plant transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Improved plant transformation vectors were constructed which utilize the pRiHRI origin of replication for highly stable maintenance in Agrobacterium tumefaciens, the ColE1 origin of replication for high copy maintenance in Escherichia coli, and a gentamycin resistance gene as a strong selectable marker for bacteria. Concise T-DNA elements were engineered with border sequences from the TL-DNA of pTiA6, the Tn5 neomycin phosphotransferase gene (npt II) expressed from either CaMV 35S or mannopine synthase (mas) promoters, and the lac Z′ gene segment from pUC18 as a source of unique restriction sites as well as an insertional inactivation marker for cloned DNA. The order of T-DNA components in all vectors is left border, plant marker cassette, lac Z′, and right border, respectively. The prototype vector, pCGN1547, was shown to be very stable in A. tumefaciens strain LBA4404 and to act as an efficient donor of T-DNA in tomato transformation experiments. Use of the other vectors is also described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00018567
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  • 63
    Digitale Medien
    Digitale Medien
    The non-conserved region of cucumopine-type Agrobacterium rhizogenes T-DNA is responsible for hairy root induction (1990)
    Springer
    Plant molecular biology 15 (1990), S. 747-753 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium ; hairy roots ; T-DNA ; geotropism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The T-DNA regions of three strains of Ri plasmids 1855, 8196, 2659 (agropine, mannopine and cucumopine type respectively) share two highly conserved regions flanking a non-homologous central part [1,2]. We have cloned segments of the cucumopine Ri plasmid 2659 T-DNA in the binary vector system Bin 19 and infected carrot discs with recombinant Agrobacterium strains. We show here that the central non-conserved region is crucial in hairy root induction as it is sufficient to induce rooting on the apical (auxin-rich) surface of carrot discs; in order to observe rooting on the basal (auxin-depleted) side of the discs, a longer T-DNA fragment, also encompassing part of the right conserved region, had to be utilized in conjunction with a Agrobacterium strain carrying aux genes. Differences of growth properties in culture are exhibited by roots transformed with different fragments of pRi 2659 T-DNA, although all transformed roots show the plagiotropic behaviour typical of hairy roots.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00016124
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  • 64
    Digitale Medien
    Digitale Medien
    Pea convicilin: structure and primary sequence of the protein and expression of a gene in the seeds of transgenic tobacco (1990)
    Springer
    Planta 180 (1990), S. 461-470 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Agrobacterium ; Convicilin ; Nicotiana (transgenic) ; Pisum (convicilin gene) ; Transgenic tobacco
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Convicilin, a trimeric globulin of pea (Pisum sativum L.) seeds, is closely related to vicilin and composed of polypeptides of 68.2 kilodaltons. A partial copy DNA (cDNA) clone encoding convicilin was isolated, sequenced, and used to select a convicilin gene from a pea genomic library. A part of the genomic clone was sequenced to obtain the coding sequences missing in the cDNA clone and a further 1 kilobase 5′ to the start of transcription were also obtained. The entire sequence of convicilin was deduced from the combined genomic and cDNA sequences. The complete gene encoding convicilin was transferred to tobacco (Nicotiana tabacum L.) and the characteristics of its expression in the seeds of transgenic plants were studied. An unprocessed polypeptide, which was found only in the seeds of the transgenic plants, was identical in size to pea convicilin, and was recognized by vicilin antibodies. Convicilin, which does not undergo posttranslational cleavage in peas, was partially processed to polypeptides of a relative molecular mass (Mr) of approx. 50000 in transgenic tobacco seeds. There was a twofold variation in the level of convicilin accumulated by the mature seeds of a number of transgenic plants and this was well correlated with the number of gene copies incorporated in the different transformants. In the seeds of tobacco plants that contained a single copy of the transferred gene it was estimated that convicilin comprised up to 2% of the seed protein. Thus, using a combination of gene sequencing and expression in a heterologous host we believe we have characterized the gene corresponding to theCvc locus, whereas the gene described by D. Bown et al. (1988, Biochem J.,251, 717–726) probably encodes a minor convicilin-related protein.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02411442
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  • 65
    Digitale Medien
    Digitale Medien
    The virB operon of Agrobacterium tumefaciens pTiC58 encodes 11 open reading frames (1990)
    Springer
    Molecular genetics and genomics 221 (1990), S. 256-266 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Vir proteins ; virB DNA sequence ; Membrane proteins ; T-DNA transport
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Agrobacterium tumefaciens genetically transforms plant cells by transferring a copy of its T-DNA to the plant where it is integrated and stably maintained. In the presence of wounded plant cells this process is activated and mediated by the products of the vir genes which are grouped into six distinct loci. The largest is the virB locus spanning 9.5 kb. Transposon mutagenesis studies have shown that virB gene products are required for virulence but their functions remain largely unknown. To provide information relevant to understanding the function of VirB polypeptides, the nucleotide sequence of the virB operon from a nopaline plasmid, pTiC58, is presented here. Eleven open reading frames (ORFs) are predicted from this sequence. The predicted sizes of 10 of the 11 VirB polypeptides are verified by specific expression in Escherichia coli. Only the product of the smallest ORF potentially encoding a 5.8 kDa polypeptide has not been detected. The initiation of translation of five virB ORFs occurs at codons that overlap the termination codons of the ORF immediately upstream; thus, translational coupling may be an important mechanism for efficient translation of the large virB polycistronic mRNA. Based on hydropathy plot analysis nine of the virB ORFs encode proteins that may interact with membranes; these data support the earlier hypothesis (Engstromm et al. 1987) that virB gene products may form a membrane pore or channel to mediate exit of the T-DNA copy (T-strands) from Agrobacterium into the plant cell. A comparison of the two published octopine virB sequences with the nopaline sequence presented here is made.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00261729
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  • 66
    Digitale Medien
    Digitale Medien
    Agrobacterium tumefaciens T-DNA gene 6b stimulates rol-induced root formation, permits growth at high auxin concentrations and increases root size (1990)
    Springer
    Molecular genetics and genomics 223 (1990), S. 1-10 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; 6b gene ; Oncogenes ; Tumour induction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary All Agrobacterium tumefaciens strains studied up to now transfer an active 6b gene to plant cells. However, the role of this gene in natural tumour induction is unknown. Various effects of 6b on plant cell growth have been described, but the precise mechanism by which 6b causes these effects has not been elucidated. Earlier experiments indicated that the 6b gene might increase auxin sensitivity as do the A. rhizogenes rol genes. The 6b gene from Tm4 (T-6b) was therefore compared with the rolB and rolABC genes. Although T-6b was unable to induce root formation, it strongly interfered with root induction and root elongation. In rolABC/T-6b coinfection experiments on carrots, T-6b-transformed cells stimulated root outgrowth of rolABC-transformed cells, indicating that the biologically active T-6b product is diffusible. Carrot rolABC roots containing the T6b gene rapidly developed into unorganized calli. Nicotiana rustica roots with rolABC and T-6b continued their development, but became very large. Fragments of such roots formed callus at α-naphthaleneacetic acid concentrations which inhibited growth of rolABC and normal root fragments, suggesting that the role of 6b genes in natural tumour induction may be to reduce the inhibitory effects of high auxin levels and to keep cells in an undifferentiated state.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00315790
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  • 67
    Digitale Medien
    Digitale Medien
    Agrobacterium plasmids encode structurally and functionally different loci for catabolism of agrocinopine-type opines (1990)
    Springer
    Molecular genetics and genomics 223 (1990), S. 465-473 
    Details
    ISSN: 1617-4623
    Schlagwort(e): Agrobacterium ; Opine catabolism ; Ti plasmids ; Agrocinopine ; Agrocin 84
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Agrobacterium tumefaciens strains C58, T37, K827 and J73, A. rhizogenes strains A4 and 15834, and A. radiobacter strain K299 were all susceptible to agrocin 84 and this sensitivity was enhanced in each case by addition of agrocinopines A and B. Analysis of transconjugants showed that sensitivity of strain A4 to agrocin 84 was encoded by pArA4a and not by the rhizogenic plasmid, pRiA4. The acc region of the A. tumefaciens nopaline-type Ti plasmid pTiC58, contained on the recombinant plasmid pTHH206, hybridized strongly to restriction fragments of plasmids from strains T37, K827, J73 and K299. Hybridizing fragment patterns generated with BamHI and EcoRI were identical among the four Ti plasmids while pAtK299 showed restriction fragment length polymorphisms at acc with the two enzymes. At moderate stringency, the pTiC58 acc region hybridized weakly to a single restriction fragment from the Ar plasmid of A. rhizogenes strain A4, but not to pTiBo542, which encodes catabolism of the closely related opines agrocinopines C and D. Plasmid pAtK84b of A. radiobacter strain K84 is induced for conjugal transfer by agrocinopines A and B. However, no hybridization was detected between this plasmid and acc from pTiC58 under conditions of moderate stringency. Like pTiC58, pAtK84b conferred transport of agrocinopines A and B on its host bacteria despite the absence of detectable sequence homology with the pTiC58-derived acc probe. However, unlike pTiC58, pAtK84b failed to confer sensitivity to or uptake of agrocin 84 on its bacterial host. These results indicate that at least four distinguishable systems exist for catabolism of the two agrocinopine opine families with the prototype locus, exemplified by acc from pTiC58, being strongly conserved among nopaline-type Ti plasmids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00264455
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  • 68
    Digitale Medien
    Digitale Medien
    Oxygen-dependent desulphation of monomethyl sulphate by Agrobacterium sp. M3C (1990)
    Springer
    Biodegradation 1 (1990), S. 229-241 
    Details
    ISSN: 1572-9729
    Schlagwort(e): Agrobacterium ; desulphation ; monomethyl sulphate ; oxygenase ; methylotrophy ; sulphate ester degradation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Agrobacterium sp. M3C, previously isolated from canal-water for its ability to grow on monomethyl sulphate, degraded this ester with stoichiometric liberation of inorganic sulphate. In contrast with the biodegradation of monomethyl sulphate in Hyphomicrobium sp., and of other longer-chain alkyl sulphates in Pseudomonas spp., the pathway in Agrobacterium appeared not to involve a sulphatase enzyme capable of catalysing ester-bond hydrolysis. No such sulphatase was detectable under a range of conditions of bacterial culture, or using various methods for preparing cell-extracts, or different assay conditions. There was no incorporation of 18O-label from H2 18O into the liberated inorganic sulphate. No methanol was detectable during biodegradation, and the organism was incapable of growth on methanol, and did not produce methanol dehydrogenase activity when grown on monomethyl sulphate. Tracer studies using mono[14C]-methyl sulphate indicated that formate serine and glycine were produced during the biodegradation. The presence of these amino acids, together with high activity of hydroxypyruvate reductase, indicated the operation of the serine pathway common in methylotrophs. Use of an oxygen electrode in conjunction with monomethyl[35S]sulphate showed that release of 35SO4 2- was dependent on availability of O2, and that there was equimolar stoichiometry among monomethyl sulphate degraded, O2 consumed and 35SO4 2- released. A proposed pathway for the degradation involved an initial mono-oxygenation to methanediol monosulphate with subsequent elimination of SO4 2- and concomitant formation of formaldehyde. The pathway was compared with degradation mechanisms for other C1 compounds and for other sulphate esters.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00119760
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  • 69
    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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  • 70
    Digitale Medien
    Digitale Medien
    A study of different (CaMV 35S and mas) promoter activities and risk assessment of field use in transgenic rapeseed plants (1955)
    Springer
    Euphytica 85 (1955), S. 411-416 
    Details
    ISSN: 1573-5060
    Schlagwort(e): Agrobacterium ; Brassica napus ; CaMV 35S promoter ; mas promoter ; gene expression ; risk assessment
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Gene fusions between the β-glucuronidase (GUS) reporter gene and the promoters of the cauliflower mosaic virus 35S RNA transcript (CaMV 35S) and the mannopine synthase (mas) genes were introduced into rapeseed varieties via Agrobacterium-mediated transformation. Fluorometric assay of β-glucuronidase activity indicated different expression patterns for the two promoters. In seedlings, the CaMV 35S promoter had maximum activity in the primary roots, while the mas promoter was most active in the cotyledons. Etiolated seedlings cultured in the dark showed reduced activity of the mas promoter. Before vernalization at the rosette stage, both promoters were more active in older plant parts than in younger ones. At this stage the highest activity was recorded in cotyledons. After the plants had bolted reduced promoter function was detected in the upper parts of the transformed plants. Both promoters were found to be functional in the majority of the studied organs of transgenic rapeseed plants, but the promoter activity varied considerably between the organs at different developmental stages. The ability of pollen to transfer the introduced genes to other varieties and related species (e.g. Brassica napus and Diplotaxus muralis) by cross-pollination was studied in greenhouse experiments, and field trials were carried out to estimate the distance for biologically-relevant gene dispersal. In artificial crossing, the introduced marker gene was transferable into other varieties of Brassica napus. In field trials, at a distance of 1 metre from the source of transgenic plants, the frequency of an outcrossing event was relatively high (10-3). Resistant individuals were found at 16 and 32 metres from the transgenic pollen donors, but the frequency of an outcrossing event dropped to 10-5.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00023974
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  • 71
    Digitale Medien
    Digitale Medien
    An assessment of morphogenic and transformation efficiency in a range of varieties of potato (Solanum tuberosum L.) (1955)
    Springer
    Euphytica 85 (1955), S. 101-108 
    Details
    ISSN: 1573-5060
    Schlagwort(e): Agrobacterium ; plant regeneration ; potato ; Solanum tuberosum ; tissue culture ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary To provide a truly genotype-independent transformation system, it is necessary to be able to transform a wide range of potato genotypes. The ability to regenerate shoots in vitro was determined for 34 potato varieties using tuber disc explants. Following a culture regime used extensively in previous studies with the variety Desiree, half of the varieties could be regenerated from tuber discs and half could not. From a sample of varieties that could be regenerated from tuber discs, all but one variety gave transgenic plants. Twelve varieties were evaluated for the capacity to regenerate shoots from leaf and internode explants excised from in vitro grown plants. All of the varieties tested regenerated adventitious shoots. Leaf and internode explants from 5 varieties were subsequently used for transformation, and transgenic plants were produced from two potato varieties that did not give transgenic plants from tuber disc explants. Some varieties could not be transformed by either method, and will require modification of the in vitro regeneration and transformation system to be successful.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00023936
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  • 72
    Digitale Medien
    Digitale Medien
    Some methodological aspects of apple transformation by Agrobacterium (1955)
    Springer
    Euphytica 85 (1955), S. 131-134 
    Details
    ISSN: 1573-5060
    Schlagwort(e): apple ; transformation ; Agrobacterium ; preculture ; azacytidine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Leaf explants of apple cvs Gala and Golden Delicious were infected with the Agrobacterium tumefaciens strain AGL0(pMOG410). The effects of a 2 d preculture of the explants before infection and the addition of 5-azacytidine to the selection medium were studied. The percentages of GUS-positive explants after 5 w did not significantly alter due to these treatments. One of the ‘Gala’ shoots, which was removed from a leaf explant cultured for 8 w on selection medium, proved to be GUS-positive and will be analyzed further. In general, however, it should be concluded that regeneration of transgenic shoots directly from leaf tissue was not very effective.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00023941
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