Authors: Tomoyuki Tani Hiroyuki Sobajima Kazunori Okada Tetsuya Chujo Shinichi Arimura Nobuhiro Tsutsumi Mikio Nishimura Hideharu Seto Hideaki Nojiri Hisakazu Yamane
Publish Date: 2007/10/16
Volume: 227, Issue: 3, Pages: 517-
Abstract
Enzyme 12oxophytodienoate OPDA reductase EC13142 which is involved in the biosynthesis of jasmonic acid JA catalyses the reduction of 10 11double bonds of OPDA to yield 3oxo22′pentenylcyclopentane1octanoic acid OPC80 The rice OsOPR1 gene encodes OPDA reductase OPR converting −cisOPDA preferentially rather than +cisOPDA a natural precursor of JA Here we provide evidence that an OPR family gene in rice chromosome 8 designated OsOPR7 encodes the enzyme involved in the JA biosynthesis Recombinant OsOPR7His protein efficiently catalysed the reduction of both enantiomers of cisOPDA similar to the OPR3 protein in Arabidopsis thaliana L Heynh The expression of OsOPR7 mRNA was induced and reached maximum levels within 05 h of mechanical wounding and drought stress and the endogenous JA level started to increase in accordance with the increase in OsOPR7 expression The GFPOsOPR7 fusion protein was detected exclusively in peroxisomes in onion epidermal cells Furthermore complementation analysis using an Arabidopsis opr3 mutant indicated that the OsOPR7 gene but not OsOPR1 was able to complement the phenotypes of male sterility in the mutant caused by JA deficiency and that JA production in the opr3 mutant was also restored by the expression of the OsOPR7 gene We conclude that the OsOPR7 gene encodes the enzyme catalysing the reduction of natural +cisOPDA for the JA biosynthesis in riceWe are most grateful to Dr Tsuyoshi Nakagawa Shimane University for providing the pGWB series vectors and Dr Yusuke Jikumaru Plant Science Center RIKEN for technical advice for JA measurement using LCMS/MS We also thank the ABRC for providing seeds of the opr3 mutant This work was supported in part by a GrantinAid for Scientific Research No 15380080 to HY from the Japanese Society for the Promotion of Science and by the Program for the Promotion of Basic Research Activities for Innovative Biosciences PROBRAIN
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