Abstract
Gibberellin (GAs) affects various aspects of plant development. Thus both biosynthesis and signal transduction of GA must be regulated precisely. GAs controls biosynthesis of themselves by GA-negative feedback through regulating the expression of GA biosynthetic and metabolic genes. For maintaining the amount of endogenous GAs, GA-negative feedback is indicated to play a central role. Among genes regulated by GA-feedback, GA3ox might be most important because it catalyzes the final step to generate active GAs. We have found only AtGA3ox1 is under GA-negative feedback among GA3oxes in Arabidopsis. We also localized cis element, designated GNFEI, necessary for the feedback, and isolated trans factor, designated AGF1, binds to GNFEI. To investigate the function of AGF1, we generated AGF1 constitutive expressor. Up-regulation of the expression of AtGA3ox1 under GA-negative feedback was observed in AGF1 constitutive expressor. We will report about further analysis of AGF1 function.
