The contribution of oxophytodienoate reductases to oxidative stress tolerance and oxylipin signalling in Arabidopsis thaliana

• Applicant: Dr. Annick Stintzi
• Subject Area: Plant Biochemistry and Biophysics
• Term: from 2008 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 76879199

A small family of six flavin-dependent oxidoreductases exists in Arabidopsis thaliana designated as oxophytodienoate reductases (OPRs). Despite their name, OPR3 is the only family member catalyzing the reduction of oxophytodienoic acid, a key step in the jasmonic acid biosynthetic pathway. The function and physiological substrates of the other OPR isozymes are unknown. Our preliminary characterization of Arabidopsis opr1, 2, and 4 loss-of-function mutants indicates a role for these enzymes in the alleviation of (photo)-oxidative stress by detoxification of lipid peroxidation products. The research proposed here aims to obtain direct evidence for the protective role of OPRs in vivo by (i) complementation of stresssensitive yeast mutants, and (ii) by gain- and loss-of-function experiments in transgenic plants. The influence of OPRs on the cellular redox status and the concentration of toxic stress-related metabolites will be analyzed. Potentially different functions for individual OPR isozymes will be addressed by transcriptome analysis in mutant vs. wild-type plants, by fluorescence microscopy to analyze subcellular targeting of OPR-GFP fusion proteins, and, at the biochemical level, by characterization of the recombinant enzymes. We expect these studies to yield important insights into the physiological role of OPRs within the complex network of genes contributing to oxidative stress tolerance, and to further our understanding of lipid peroxidation products as mediators of oxidative stress and, possibly, as signals in development and/or stress acclimation.

• DFG Programme: Research Grants