Functional Characterization of Oxophytodienoate Reductases in Arabidopsis

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. This research project aims to obtain direct evidence for the protective role of OPRs in vivo by (i) complementation of stress-sensitive 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 are analyzed. Potentially different functions for individual OPR isozymes are 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 adaptation.

Dissertations:

Saeid Abu-Romman (2008): Functional Characterization of 12-Oxophytodienoate Reductases in Arabidopsis. Verlag Grauer, Beuren, Stuttgart; ISBN 978-3-86186-550-6

Mahmoud Saleh Mahmoud Mohamed (2013): Alleviation of oxidative stress and detoxification of lipid peroxidation products by flavin-dependent oxidoreductases in plants. In: Schriftenreihe zur Physiologie und Biotechnologie der Pflanzen (Hrsg. A. Schaller), Bd. 2, Cuvillier Verlag, Göttingen; ISBN 978-3-95404-338-5 http://www.cuvillier.de/flycms/de/html/30/-UickI3zKPS32f0g=/Buchdetails.html

Nadja Liebig (2013): The role of flavin-dependent oxidoreductases in stress tolerance and detoxification of reactive carbonyls. In: Schriftenreihe zur Physiologie und Biotechnologie der Pflanzen (Hrsg. A. Schaller), Bd. 3, Cuvillier Verlag, Göttingen; ISBN 978-3-95404-336-9 http://www.cuvillier.de/flycms/de/html/30/-UickI3zKPS33d0g=/Buchdetails.html

Publications:

Bosch, M., Wright, L.P., Gershenzon, J., Wasternack, C., Hause, B., Schaller, A., and Stintzi, AJasmonic acid and its precursor 12-oxophytodienoic acid control different aspects of constitutive and induced herbivore defenses in tomato. Plant Physiol. Vol. 166

Bosch, M., Berger, S., Schaller, A., Stintzi, A. (2014) Jasmonate-dependent induction of polyphenol oxidase activity in tomato foliage is important for defense against Spodoptera exigua but not against Manduca sexta. BMC Plant Biol.

Abu-Romman S., Liebig N., Mohamed M.S.M., Freihart M., Schaller A., Stintzi A. (2013): Oxophytodienoate
reductases 1 and 2 contribute to reactive carbonyl detoxification and the alleviation of photooxidative stress in Arabidopsis; submitted