The role of flavin-dependent oxidoreductases in stress tolerance and detoxification of reactive carbonyls

The oxophytodienoic acid reductase (OPR) family in Arabidopsis thaliana consists of six members. Except from OPR3, which is a key regulator in jasmonic acid biosynthesis, the OPRs seem to be involved in the detoxification of lipid peroxidation products during abiotic stress. The loss-of-function mutants of OPR1, 2 and 4 are highly sensitive to highlight stress and genetic complementation of these mutants restore wild-type levels, confirming a role in high-light stress tolerance. In addition, several stress-related metabolites accumulate in the opr mutants. OPR4 has also a senescence promoting function. OPR1 and 2 are localized in the cytosol and are able to reduce the double bond of lipid peroxidation-derived α,β-unsaturated carbonyls in vitro. OPR4, on the other hand, is hardly soluble when expressed heterologously and possesses no catalytic activity. However, its relocalization to processing bodies after stress proves its stress-related function.