シロイヌナズナの種子発芽過程におけるジベレリン生合成酵素遺伝子の発現制御

概要

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Gibberellin (GA) plays an essential role during germination of Arabidopsis seeds. We studied the regulation of two Arabidopsis genes, AtGA3ox1 (GA4) and AtGA3ox2 (GA4H), both of which encode GA 3-oxidase that catalyze the final biosynthetic step to produce bioactive GAs. These two genes are expressed during seed germination with distinct temporal patterns of mRNA accumulation. In situ hybridization showed that both AtGa3ox1 and AtGA3ox2 transcripts are predominantly localized in cortical cells in embryo axis during seed germination. Interestingly, in contrast to the AtGA3ox1 gene, the AtGA3ox2 gene was not down-regulated by GA activity. Therefore, the AtGA3ox2 gene may play an important role in the maintenance of bioactive GA levels during seed germination. The Arabidopsis AtCPS (GAl) gene encodes copalyl diphosphate synthase which catalyzes an early step of the GA biosynthetic pathway. Unlike the AtGA3ox genes, AtCPS-GUS expression is localized in shoot apex and provasculature during seed germination. Distinct localization patterns of these genes suggest intercellular translocation of a GA intermediate. To determine which intermediate could be transported, we are examining cellular localization of other GA biosynthetic genes in germinating seeds.
植物化学調節学会の論文
2000-11-02