An Overview of Gibberellin Metabolic Enzyme Genes in Rice

Abstract

To enhance our understanding of gibberellin (GA) metabolism in rice (Oryza sativa L.), we identified 29 candidate genes encoding the following GA metabolic enzymes: ent-copalyl diphosphate synthase (CPS), ent-kaurene synthase (KS), ent-kaurene oxidase (KO), ent-kaurenoic acid oxidase (KAO), GA 20-oxidase (GA20ox), GA 3-oxidase (GA3ox), and GA 2-oxidase (GA2ox). In contrast to Arabidopsis, multiple CPS-like, KS-like, and KO-like genes were identified in rice, most of which are contiguously arranged. We demonstrated that the enzymes catalyzing the early steps (i.e. CPS, KS, KO, and KAO) are encoded by single genes, while those for later steps (i.e. GA20ox, GA3ox, and GA2ox) are encoded by gene families. The remaining CPS-like, KS-like, and KO-like genes were likely to be involved in biosynthesis of diterpene phytoalexins rather than GAs, because the expression of some genes were up-regulated by UV irradiation and elicitor treatment.