OPR3

OPR3, short for 12-oxophytodienoate reductase 3, is a gene in Arabidopsis thaliana encoding an enzyme of the old yellow enzyme (OYE) family that functions in jasmonic acid biosynthesis. The enzyme is a peroxisomal NADPH-dependent oxidoreductase that reduces 12-oxophytodienoic acid (OPDA) to a downstream intermediate in the pathway toward jasmonic acid (JA). OPR3 is one of several paralogs in the OPR gene family; OPR1 and OPR2 are related enzymes with overlapping expression patterns but often distinct tissue specificity or stress responses.

Expression of OPR3 is regulated by developmental and environmental cues and is associated with wounding, insect herbivory, and other stresses that activate JA signaling. In many studies, loss-of-function opr3 mutants show strongly reduced JA accumulation and attenuated expression of JA-responsive genes, revealing OPR3’s central role in JA biosynthesis under stress conditions. Phenotypic consequences in such mutants include diminished defense responses to herbivores and pathogens, as well as JA-dependent developmental processes.

Biochemically, OPR3 operates in the peroxisome as part of the JA biosynthetic module that converts OPDA to JA precursors via beta-oxidation. The enzyme’s activity helps regulate JA levels and thereby modulates downstream signaling networks across plant tissues.

Overall, OPR3 is considered a core component of the jasmonate synthesis pathway in Arabidopsis and related species, contributing to the plant’s ability to mount rapid defense responses and to coordinate growth and development in response to environmental challenges.