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First published online April 9, 2004; 10.1104/pp.103.033696 Plant Physiology 134:1642-1653 (2004) © 2004 American Society of Plant Biologists An Overview of Gibberellin Metabolism Enzyme Genes and Their Related Mutants in Rice1,[w]Field Production Science Center, University of Tokyo, Nishi-Tokyo, Tokyo 1880002, Japan (T.S.); Bioscience and Biotechnology Center, Nagoya University, Nagoya, Aichi 4648601, Japan (K.M., H.I., T.T., M.U.-T., H.K., M.A., M.M.); BioResource Center, RIKEN Tsukuba Institute, Tsukuba, Ibaraki 3050074, Japan (K.I., M.K.); and Molecular Genetics Department, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 3058602, Japan (G.K.A., S.T., K.A., A.M., H.H.)
To enhance our understanding of GA metabolism in rice (Oryza sativa), we intensively screened and identified 29 candidate genes encoding the following GA metabolic enzymes using all available rice DNA databases: 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 the Arabidopsis genome, multiple CPS-like, KS-like, and KO-like genes were identified in the rice genome, most of which are contiguously arranged. We also identified 18 GA-deficient rice mutants at six different loci from rice mutant collections. Based on the mutant and expression analyses, we demonstrated that the enzymes catalyzing the early steps in the GA biosynthetic pathway (i.e. CPS, KS, KO, and KAO) are mainly 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 the biosynthesis of diterpene phytoalexins rather than GAs because the expression of two CPS-like and three KS-like genes (OsCPS2, OsCPS4, OsKS4, OsKS7, and OsKS8) were increased by UV irradiation, and four of these genes (OsCPS2, OsCPS4, OsKS4, and OsKS7) were also induced by an elicitor treatment.
1 This work was supported by the Ministry of Agriculture, Forestry and Fisheries of Japan (Rice Genome Project; grant no. IP1010 to T.S.), the Program for Promotion of Basic Research Activities for Innovation of Biosciences (grant to M.U.-T. and H.K.), and the Ministry of Education, Culture, Sports, Science and Technology (Grant-in-Aid for the Center of Excellence to M.M.). [w] The online version of this article contains Web-only data. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.103.033696. * Corresponding author; e-mail makoto{at}nuagr1.agr.nagoya-u.ac.jp; fax 81527895226. Received September 22, 2003; returned for revision December 23, 2003; accepted January 9, 2004.
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