| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1997: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1996: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
Flavonoids are belived to play an important role in protection against biotic and abiotic attacks. The primary aim of this project is to elucidate the molecular mechanism of flavenoid biosynthesis in response to the emviromnental stimuli.
Chalcone synthase (CHS), the first step enzyme of flabonoid biosynthesis, is encoded by seven genes in soybean. In this research, we quantitatively analyzed the expression levels of each member in soybean seedlings. Expression of chs7 was induced very early reaching its peak within 6 hours post imbibition. Ultraviolet (UV) -B response of the gene family was found to emerge during 24 hours of imbibition, suggesting a developmental control of the machinery in the germinating embryo. In three-day-dark-grown seedlings, all the seven genes responded to white light and showed up-regulation by UV-Bwith substantial variation in their response among the members.
Some flavonoids are also reported to function as inducer of Rhizobium-legume symbiosis and this is inhibited by nitrate in the growth medium. Here we investigated if expression of CHS genes in soybesn is regulated by the presence of nitrate in the medium and found that expression of gene 7 was inhibited by nitrate and that this kind of response to the nitrogen compound was specifically observed in legume plants.
Most of the light-responsive chs genes contain an H-box except for the least responsive gene, chs2. The H-box is reported to be recognized by MYB-homologous P element in maize, which activates in trans flavonoid genes. In this project, we isolated the whole region of the soybean NYB-homologous genes, Gmmyb10 and Gmmyb29, whose expression was found up-regulated by UV-B.We intend to use thses genes to manipulate flavonoid biosynthesis in legume.
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