Abstract
Rice eui mutants show drastic elongation of the final internode at the heading stage. We have reported that the EUI gene encodes a cytochrome P450, CYP714D1, and function as a novel gibberellin (GA) deactivation enzyme that epoxidizes the C16(17) double bond of GAs. In Arabidopsis, CYP714A1 is the closest gene to the CYP714D1 in sequence. To clarify the possible function of CYP714A1 in the GA metabolism pathway, enzymatic activity of recombinant CYP714A1 proteins were analyzed in a yeast expression system. We found that GA12 was metabolized into an unknown compound, which was distinct from 16α,17-epoxy GA12, the product of CYP714D1 protein. In comparison with GA12, this product did not induce growth promotion when applied to the GA-deficient ga1-3 mutant. Furthermore, transgenic Arabidopsis plants overexpressing CYP714A1 showed severe dwarfism like the ga1-3 mutant. These results indicate that CYP714A1 functions as a GA deactivation enzyme in Arabidopsis.
