An Arabidopsis gene induced by wounding functionally homologous to flavoprotein oxidoreductases

The regulation of genes in response to wounding is mediated in part by the octadecanoids 12-oxo-phytodienoic acid (OPDA), jasmonic acid (JA) and its m ethyl ester methyl jasmonate (MeJA). We identified, by differential display , an Arabidopsis gene (OPR3) induced after wounding. OPR3 is homologous to members of the flavin mononucleotide (FMN) binding proteins, including the old yellow enzyme (OYE) from yeast and 12-oxophytodienoate-10,11-reductase (OPR) from Arabidopsis. Transcripts of OPR3 rapidly accumulated in leaves a fter wounding and MeJA treatment, but they were detected in various tissues of unwounded plants at relatively low levels. Expression of the OPR3 gene was significantly reduced in wounded leaves of the coi1 mutant, indicating partial dependence on jasmonate perception for full induction of the gene. The recombinant protein of OPR3 cross-reacted with an antiserum raised agai nst the OYE protein, and showed oxidation of beta -NADPH when OPDA or 15-de oxy-Delta (12,14)-prostaglandin J2 (PGJ2), an analogue of OPDA, was used as substrate. beta -NADPH oxidation was not observed when MeJA, which lacks t he double bond in the ketone ring, was used as substrate. The recombinant O PR3 protein also showed beta -NADPH oxidation activity in the presence of c yclohexenone, but not cyclohexanone, suggesting that the enzyme has specifi city to cleavage of olefinic bonds in cyclic enones. The results show that the OPR3 gene product represents a new OPR of Arabidopsis induced after wou nding.