29.イネOsOPR7遺伝子にコードされるタンパク質はジャスモン酸生合成に関与する12-オキソフィトジエン酸還元酵素である(口頭発表)

概要

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The enzyme 12-oxophytodienoate (OPDA) reductase, which is involved in the biosynthesis of jasmonic acid (JA), catalyses the reduction of OPDA to yield 3-oxo-2-(2'-pentenyl)-cyclopentane-1-octanoic acid. The rice OsOPRl gene encoding OPDA reductase (OPR) converts (-)-cis-OPDA preferentially, rather than (+)-c/s-OPDA, a natural precursor of JA; therefore, another OPR to convert the natural substrate is assumed to function in the JA biosynthetic pathway in rice. Here, we provide evidence that an OPR family gene in rice chromosome 8, designated OsOPR7, encodes the enzyme involved in the JA biosynthesis in rice. Recombinant OsOPR7-His protein efficiently catalysed the reduction of both enantiomers of cw-OPDA, similar to the Arabidopsis OPR3 protein. The expression of OsOPR7 mRNA was induced and reached maximum levels within 0.5 h of mechanical wounding and drought stress, and the endogenous JA level started to increase in accordance with the increase in OsOPR7 expression. 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 reduction of the natural (+)-cis-OPDA for the JA biosynthesis in rice.
植物化学調節学会の論文
2007-10-05