15. イネのジャスモン酸生合成に関与する12-oxophytodienoic acid reductase 8 (OsOPR8)の機能解析

概要

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12-Oxophtrodienoic acid reductase (OPR) is one of jasmonic acid (JA) biosynthetic enzymes. Although in Arabidopsis thaliana and Lycopersicon esculentum there exist a few OPR isozymes, only AtOPR3 and LeOPR3 have been shown to be involved in JA biosynthesis in A. thaliana and L. esculentum, respectively. Biological functions of AtOPR1, AtOPR2, and LeOPR1 remains to be clarified. We found that more than 10 OPR genes exist in rice using a rice (O. sativa L. cv. Nipponbare) genome database recently opened to the public. One of these OPRs, tentatively named OPR8, has the peroxisomal targeting signal, as in the cases of AtOPR3 and LeOPR3, and fusions of OsOPR8 with Green Fluorescent Protein were detected exclusively in peroxisomes of onion epidermal cells. OsOPR8 expressed in a functional form in E. coli exhibited AtOPR3-like activity that reduces effectively naturally occurring (+)-cis-OPDA. It was also shown that both of the OsOPR8 mRNA and endogenous JA levels in rice leaves began to increase within 1/4 h after the wounding and drought treatments. These results strongly suggest that OsOPR8 is the OPR responsible for JA biosynthesis in rice. In addition, we are now investigating whether the male-sterility in opr3 (a T-DNA-tagged, male-sterile mutant of Arabidopsis) is alleviated by transformation of the mutant with an OsOPR8 cDNA.
植物化学調節学会の論文
2005-10-13