| Budget Amount *help |
¥4,300,000 (Direct Cost: ¥4,300,000)
Fiscal Year 1989: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1988: ¥3,100,000 (Direct Cost: ¥3,100,000)
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| Research Abstract |
It is well known that Cichorium intybus requires low temperature and long day treatments for the flower bub differentiation. However, Cichorium plants transformed with T-DNA of Ri plasmid exhibited flower formation without low temperature treatment under a long day condition. Similar phenomenon of flower bud formation without low temperature treatment was also observed in Cichorium plants transformed with single rol C gene located on the T-DNA of Ri plasmid. When not-transformed (normal) Cichorium plants were treated with some plant growth regulators, such as gibberellin, anti-gibberellin, cytokinin, and ethylene, gibberellin (GA_3) induced the stem elongation, but not the flower bud differentiation. On the other hand, anti-gibberellin (S-3307, a potent inhibitor of gibberellin biosynthesis) induced the flower bud differentiation with low frequency.
Moreover, when Cichorium plants transformed with Ri T-DNA were treated with GA_3, flower bud formation could not be observed. These results indicate that a possible physiological function of Ri T-DNA is an inhibition of gibberellin biosynthesis or a suppression of gibberellin activity).
Qualitative and quantitative analyses of endogenous gibberellin in Atropa belladonna transformed with Ri T-DNA were carried out by using radio-immunoassay with monoclonal antibodies against some gibberellins. The major gibberellin in the transformed and normal plants was GA_1, and the contents of GA_1 in the transformed plants was less than 1/100 as compared to that of the normal plants. This result suggests that some physiological responses (including dwarfism) observed specifically in plants transformed with Ri T-DNA were induced by the decrease of endosenous gibberellin contents in the transformed plants.
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