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  • 1
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Molecular investigation of the process of cold acclimation in woody plants has been limited by the superimposition of dormancy-related events on the process of cold tolerance development. To address this limitation, we have used the grape Vitis labruscana L. ev. Concord to develop a system in which the developmental programme of dormancy can be induced seperately from cold acclimation. Using this system we have characterized differential accumulation of several proteins in grape buds during the normally superimposed endodormancy and cold acclimation programmes, and in buds which have entered only the endodormancy programme. A set of 47 kD proteins accumulated during endodormancy without cold acclimation to a level similar to that found in endodormant and cold-acclimated buds, but without any associated increase in bud cold-acclimation level. However, a 27 kD LEA-like protein accumulated only in cold acclimated buds. We conclude that expression of the 47 kD glycoprotein is endodormancy-related, but is not strictly related to the development of cold acclimation, while the 27 kD protein appears to be more specific to cold acclimation. In addition to strengthening the association of LEA-like proteins with cold acclimation, this system allows more specific assessment of cold acclimation-associated phenomena in overwintering buds.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A cDNA clone encoding an isoform of the plasma membrane H+-ATPase was isolated from Nicotiana tabacum. The steady-state plasma membrane H+-ATPase message levels were the same in unadapted tobacco cells and tobacco cells adapted to 428 mol m−3 NaCl. When cells adapted to 428 mol m−3 NaCl maintained in the absence of NaCl (deadapted) for an excess of 100 passages were exposed to 400 mol m−3 NaCl for 24 h, there was an increased accumulation of plasma membrane H+-ATPase message. The NaCl responsiveness of the deadapted cells was dependent upon the growth cycle stage. Alterations in the levels of plasma membrane FT-ATPase message during the growth cycle support a role for the H+-ATPase in cell growth. These results document the induction by NaCl of plasma membrane FT-ATPase message accumulation in tobacco cells, and suggest that enhanced expression of the plasma membrane FT-ATPase has a role in the short term response of cells of NaCl, but is not necessarily involved in long-term adaptation.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Plants were regenerated from both the wild type and a stable NaCI-tolerant line of tobacco cells (Nicotiana tabacum/gossii). The regeneration process was much more difficult in the case of the NaCI-tolerant line and was only successful in the absence of NaCI. These plants differed morphologically from those regenerated from the wild type cell line, exhibiting abnormally short internodes, small leaves and reduced growth. Cell suspension cultures derived from plants regenerated from the stable NaCI-tolerant line retained a high level of tolerance to salt. The NaCI-concentration required to reduce fresh and dry weight gain by 50% was about twice that observed in the case of the cells obtained from wild type plants.The results presented here, together with those of Watad et al. (1985), indicate that resistance to salt is operating and stable at the cellular level before and after plant regeneration. When the regenerated plants were grown in increasing levels of salt their growth response was not clearly different from that of the plants regenerated from the wild type cell line. However, the survival of plants on high concentrations of NaCI tended to be higher in the case of plants regenerated from the NaCI-tolerant cell line.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell reports 8 (1990), S. 676-679 
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plants regenerated from tobacco (Nicotiana tabacum L. cv. Wisconsin 38) cells that were adapted to 428 mM NaCl were found to have hexaploid or near-hexaploid chromosome numbers compared to the normal tetraploid, 2N(2C)=4X=48 chromosome numbers of plants regenerated from unadapted cells. Even though cells with chromosome numbers other than hexaploid were found in the cell population only hexaploid plants were regenerated. The hexaploid condition may impart some karyotypic stability that allows more efficient morphogenic activity. The hexaploid condition could not be correlated with several phenotypic alterations associated with plants regenerated from adapted cells, including male sterility and increased salt tolerance.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-203X
    Keywords: Key words Lily ; Transformation ; Bialaphos ; Adventitious shoot regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have obtained transgenic lily (Lilium longiflorum) plants after microprojectile bombardment, using the Biolistics PDS 1000/He system, of morphogenic calli derived from bulblet scales, followed by bialaphos selection. Parameters which gave the highest transient uidA expression were used: a bombardment pressure of 1100 psi, a target distance of 6 cm and a 48-h preculture on medium with 3% sucrose. A total of 1800 morphogenic calli were co-bombarded with plasmids containing either the uidA reporter or PAT selectable marker genes. After bombardment, the calli were exposed to 2 mg/l bialaphos. Only 72 of the shoot-forming calli (4%) survived. The 72 shoot clusters produced 342 shoots on elongation medium containing 0.5 mg/l bialaphos. Only 55 plantlets survived subsequent exposure to 2.0 mg/l bialaphos. PCR analysis indicated that 19 of these plantlets contained the PAT transgene. Southern analysis of 3 of the plants indicated that all contained the PAT gene.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-203X
    Keywords: Key words Peppermint ; Transformation ; Co-cultivation ; Coconut water ; Selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Substantial improvement in peppermint (Mentha x piperita L. var. Black Mitcham) genetic transformation has been achieved so that the frequency of transgenic plants regenerated (percent of leaf explants that produced transformed plants) was 20-fold greater than with the original protocol. Essential modifications were made to conditions for Agrobacterium tumefaciens co-cultivation that enhanced infection, and for selection of transformed cells and propagules during regeneration. A systematic evaluation of co-cultivation parameters established that deletion of coconut water from the co-cultivation medium resulted in substantially increased transient β-Glucuronidase (GUS) activity, in both the frequency of explants expressing gusA and the number of GUS foci per explant (〉700 explants). Co-cultivation on a tobacco cell feeder layer also enhanced A. tumefaciens infection. Enhanced transformation efficiencies were further facilitated by increased selection pressure mediated by higher concentrations of kanamycin in the medium during shoot induction, regeneration, and rooting: from 20 to 50 mg/l in shoot induction/regeneration medium and from 15 to 30 mg/l in rooting medium. Raising the concentration of kanamycin in media substantially lowered the number of "escapes" without significant reduction in plant regeneration. These modifications to the protocol yielded an average transformation frequency of about 20% (〉2000 explants) based on expression of GUS activity or the tobacco antifungal protein, osmotin, in transgenic plants. Genetic transformation of peppermint has been enhanced to the extent that biotechnology is a viable alternative to plant breeding and clonal selection for improvement of this crop.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-203X
    Keywords: Key words Peppermint ; Transformation ; Agrobacterium ; GUS ; Transgenic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The first transgenic peppermint (Mentha×piperita L. cultivar Black Mitcham) plants have been obtained by Agrobacterium-mediated transformation by cocultivation with morphogenically responsive leaf explants. Basal leaf explants with petioles, from leaves closest to the apex of in-vitro-culture-maintained shoots (5 cm), exhibited optimal shoot organogenetic responsiveness on medium supplemented with thidiazuron (8.4 µm). Shoot formation occurred at sites of excision on the leaf blade and petiole either directly from cells of the explant or via a primary callus. Analyses of transient GUS activity data indicated that DNA delivery by microprojectile bombardment was more effective than Agrobacterium infection. However, no transgenic plants were obtained from over 22,000 leaf explants after particle bombardment. Cocultivation of leaf explants with Agrobacterium strain EHA 105 and kanamycin selection produced transgenic plants. Greater transient and stable -glucuronidase (GUS) activities were detected in explants or propagules transformed with the construct where gusA was driven by the pBISN1 promoter rather than a CaMV 35S promoter. Eight plants were subsequently regenerated and verified as transgenic based on detection of the nptII transgene by PCR and Southern blot analyses. The Southern analyses indicated that the plants were derived from eight unique transformation events. All transgenic plants appeared morphologically normal. Analyses of GUS activities in leaves sampled from different portions of these transgenic plants, 10 months after transfer to the greenhouse, indicated that six out of the eight original regenerants were uniformly transformed, i.e., did not exhibit chimeric sectors.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cultured tobacco (Nicotiana tabacum L. cv. Wisconsin 38) cells were found to have altered DNA contents and chromosome numbers after adaptation to NaCl. Cells adapted to 428 mM NaCl were predominately hexaploid compared to the normal tetraploid 2N(2C)=4X=48 chromosome number of unadapted cells. Enrichment of the cell population for hexaploid cells occurred only after exposure to higher NaCl (428 mM), not lower levels of NaCl (171 mM). The majority of adapted cells remain hexaploid for at least 25 cell generations after removal from NaCl exposure. Adapted cell populations were found to have fewer cells with highly polyploid (2N≥96) nuclei. Salt tolerance of hexaploid cells was not found to be significantly greater than that of tetraploid cells. Cells with higher ploidy levels were less salt tolerant. It is suggested that high levels of NaCl induce polyploidization and that exposure to NaCl selects against cells with very high ploidy levels.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 82 (1991), S. 430-440 
    ISSN: 1432-2242
    Keywords: Solanum tuberosum L. ; Adventitious regeneration ; Heritability ; Statistical analyses ; Quantitative traits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Approximately 1,600 potato (Solanum tuberosum L.) plants of the cultivar ‘Superior’ were regeneratedin vitro from meristems adventitiously initiated on tuber disc expiants. Direct regeneration from tuber disc cells, by passing a callus intermediary, is efficient and results in low frequencies of plants with gross phenotypic aberrations. The somaclonal plant population was statistically characterized in field plots over five asexual generations and in three diverse locations. When compared in advanced generations to a large population of control plants propagated from stem cuttings, the means of the somaclonal population were significantly different, often shifted in the desirable direction, for 16 of 22 horticulturally important traits. Somaclonal population variances statistically exceeded those of the controls for 13 of the 22 traits. Regressions between consecutive tuber generations and between locations or replications (blocks) within a generation were significant in the somaclonal population for all traits analyzed. In a few instances, significant control population regressions occurred that are interpreted to be the result of non-random, non-genetic factors primarily affecting control plants of low vigor. Selected somaclones exhibiting desirable alterations for yield, tuber number and shape, and vigor were stable over more than two consecutive asexual generations.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 87 (1993), S. 305-313 
    ISSN: 1432-2242
    Keywords: Adventitious regeneration ; Potato cultivars ; Quantitative traits ; Solanum tuberosum L. ; Statistical analyses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Three somaclonal populations of potato (Solanum tuberosum L.), each comprised of at least 1,000 plants, were regenerated from the cultivars Kennebec, Russet Burbank, and Superior. The frequency of formation of adventitious meristems from tuber disc explants varied significantly between these potato genotypes. Only 1.0–1.3% of each somaclonal population exhibited morphological aberrations. Regenerated populations of ‘Kennebec’ and ‘Superior’, when compared to respective control populations over three asexual generations, were similarly enriched with somaclones having more elongated tubers, a higher total tuber number and weight, a higher cull tuber number and weight, and earlier maturity. Somaclones of ‘Russet Burbank’ also produced more elongated tubers, a higher total tuber number, and a higher cull tuber number and weight but, in contrast, these somaclones were lower in total tuber weight, lower in U.S. 1 tuber number and weight, shorter in stem length, and lower in vigor. Of the three cultivars, ‘Russet Burbank’ somaclones possessed the greatest variability for most traits. Besides this significant genotype effect, quantitative traits differed amongst each other in respect of relative changes resulting from somaclonal variation. Observed differences among genotypes and quantitative traits will undoubtedly affect the success or failure of plant improvement programs attempting to utilize somaclonal variation.
    Type of Medium: Electronic Resource
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