(1000-03) A reduction signaling by a glutathione relays a 12-oxophytodienoic acid signal in coordinating growth and defense responses under environmental stresses in Arabidopsis
Body of Abstract: In nature, plants must complete their life cycles fast enough, yet maintain the defense capability necessary to survive against arrays of consistent environmental stresses. However, molecular modus operandi underlying the growth-defense coordination are mostly unknown. Here, we describe a unique role of glutathione (GSH) in relaying 12-oxophytodienoic acid (OPDA) signaling to cross-regulate growth and defense: in concert, optimizing plant plasticity and survival potential. Under stresses, GSH accumulations induced by OPDA signaling in the chloroplasts stimulates protein S-glutathionylation, modulating the structure and function of redox-sensitive enzymes such as 2-cysteine (Cys) peroxiredoxin A (2CPA). GSH exchanges thiol-disulfides with the resolving CysR53, while donating an electron (e-, H+) to the peroxidatic CysP175, of 2CPA, which revives its reductase activity and in turn fosters peroxide detoxification in photosynthesis. Concurrently, GSH prompts retrograde signaling from plastids to nucleus in rapidly adjusting OPDA-responsive gene expressions, and actuating defenses responses against various ecological constraints such as salinity, excess oxidant and light, as well as mechanical wounding. We thus conclude that GSH is an autonomous, versatile signal molecule that delivers various cellular and environmental cues to a multitude of plant physiological, e.g., growth, development, stress defense and acclimation, processes.