455 / 2019-02-26 12:50:52

CYP72A Enzymes Catalyzed 13-Hydrolyzation of Gibberellin Are Indispensable for Primary Seed Dormancy in Brassicaceae Plants

13-OH GA,13-H GA,13-hydroxylase,Arabidopsis,cytochrome P450,CYP72A

全体主题 > Metabolism

Bioactive gibberellins (GAs, diterpenes) are essential hormones in land plants, which control many aspects of plant growth and developments. In flowering plants, 13-OH (low bioactivity; such as GA1) and 13-H GAs (high bioactivity; such as GA4) frequently coexist. However, the bona fide GA 13-hydroxylase and its physiological functions in Arabidopsis remain unknown. Here, we report that novel cytochrome P450 genes (CYP72A9 and its homologs) encode active GA 13-hydroxylases in Brassicaceae plants. CYP72A9-overexpressing plants show semi-dwarfism which caused by significant reduction in GA4. Biochemical assays showed that recombinant CYP72A9 protein catalyzed the conversion from 13-H GAs to corresponding 13-OH GAs. CYP72A9 was expressed predominantly in developing seeds in Arabidopsis. Fresh harvested seeds of cyp72a9 mutants germinated more quickly than wild-type, while long-term storage and stratification treated seeds did not. Evolutionary origin of GA 13-oxidases from CYP72A subfamily is also investigated and discussed.