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  • DNA/RNA hybridization  (1)
  • Transgenic potato  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Synthesis of fructans in tubers of transgenic starch-deficient potato plants does not result in an increased allocation of carbohydrates (1996)
    Springer
    Planta 199 (1996), S. 528-536 
    Details
    ISSN: 1432-2048
    Keywords: Erwinia ; Fructan ; Levan sucrase ; Transgenic potato ; Sink strength ; Solanum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Inhibition of starch biosynthesis in transgenic potato (Solanum tuberosum L. cv. Désirée) plants (by virtue of antisense inhibition of ADP-glucose pyrophosphorylase) has recently been reported to influence tuber formation and drastically reduce dry matter content of tubers, indicating a reduction in sink strength (Müller-Röber et al. 1992, EMBO J 11: 1229–1238). Transgenic tubers produced low levels of starch, but instead accumulated high levels of soluble sugars. We wanted to know whether these changes in tuber development/sink strength could be reversed by the production of a new high-molecular-weight polymer, i.e. fructan, that incorporates sucrose and thereby should reduce the level of osmotically active compounds. To this end the enzyme levan sucrase from the gram-negative bacterium Erwinia amylovora was expressed in tubers of transgenic potato plants inhibited for starch biosynthesis. Levan sucrase was targeted to different subcellular compartments (apoplasm, vacuole and cytosol). Only in the case of apoplastic and vacuolar targeting was significant accumulation of fructan observed, leading to fructan representing between 12% and 19% of the tuber dry weight. Gel filtration and 13C-nuclear magnetic resonance spectroscopy showed that the molecular weight and structure of the fructan produced in transgenic plants is identical to levan isolated from E. amylovora. Whereas apoplastic expression of levansucrase had deleterious effects on tuber development, tubers containing the levansucrase in the vacuole did not differ in phenotype from tubers of the starch-deficient plants used as starting material for transformation with the levansucrase. When tuber yield was analysed, no increase but rather a further decrease relative to ADP-glucose pyrophosphorylase antisense plants was observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195183
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  • 2
    Electronic Resource
    Electronic Resource
    Transformation of soybean protoplasts from permanent suspension cultures by cocultivation with cells of Agrobacterium tumefaciens (1987)
    Springer
    Plant molecular biology 9 (1987), S. 135-145 
    Details
    ISSN: 1573-5028
    Keywords: azacytidine ; DNA/RNA hybridization ; gene expression ; marker rescue ; nopaline-synthase ; plant tumor cells ; Ti-plasmid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell wall regenerating protoplasts from soybean cells kept in suspension culture were cocultivated with bacteria which were derived from the nopaline strain C58 of Agrobacterium tumefaciens. When the bacteria carried an oncogenic Ti-plasmid, about 5% of the surviving protoplasts were able to form calli on hormone-free agar in contrast to controls, where bacteria without Ti-plasmid were applied, and where no calli were formed. After isolation of DNA from hormone-independently growing cells further evidence for transformation was obtained by hybridization to Ti-plasmid specific RNA and by rescue of a segment with a bacterial resistance gene which had been inserted before into the T-DNA. Transfer of T-DNA harboring a neomycin-resistance gene activated by the nos-promoter resulted in calli growing on kanamycin. Verification of segments located at the left and the right part of the T-DNA indicated the presence of its entire length in transformed soybean cells. Expression of T-DNA genes was measured by the assay of nopaline-synthase. Cells cultured on agar had a much higher level of nopaline-synthase than fast growing cells in suspension culture. Transferring them to agar or treatment with azacytidine strongly increased synthesis of nopaline-synthase indicating a reversible repression presumably via a methylation mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00015646
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    Paper (German National Licenses)
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