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Single Oxygen-Induced Cell Death in Arabidopsis under High-Light Stress Is controlled by OXI1 Kinase

Single Oxygen-Induced Cell Death in Arabidopsis under High-Light Stress Is controlled by OXI1 Kinase

Leonard Shumbe, Anne Chevalier, Bertand Legeret, Ludivine Taconnat, Fabien Monnet and Michel Havaux
a. CEA, Direction des Sciences du Vivant, Institut de Biologie Environnementale et de Biotechnologie, F13108 Saint-Paul-lez-Durance, France (L.S., A.C., B.L., F.M., M.H.)
b. CNRS, UMR 72565 Biologie Végétale et Microbiologie Environnementales, F-13108 Saint-Paul-lezDurance, France (L.S., A.C., B.L., F.M., M.H.)
c. Aix-Marseille Université, F-13284 Marseille, France (L.S., A.C., B.L., F.M., M.H.)
d. POPS Transcriptomic Platform, Institute of Plant Sciences Paris-Saclay IPS2, Rue de Noetzlin, 91405 Orsay, France (L.R.)
e. Université Avignon et des Pays de Vaucluse, 84000 Avignon, France (F.M.)  

Abstract

Studies of the singlet oxygen (1O2)-overproducing flu and chlorina1 (ch1) mutants of Arabidopsis (Arabidopsis thaliana) have shown that 1O2-induced changes in gene expression can lead to either programmed cell death (PCD) or acclimation. A transcriptomic analysis of the ch1 mutant has allowed the identification of genes whose expression is specifically affected by each phenomenon. One such gene is OXIDATIVE SIGNAL INDUCIBLE1 (OXI1) encoding an AGC kinase that was noticeably induced by excess light energy and 1O2 stress conditions leading to cell death. Photo-induced oxidative damage and cell death were drastically reduced in the OXI1 null mutant (oxi1) and in the double mutant ch1*oxi1 compared with the wild type and the ch1 single mutant, respectively. This occurred without any changes in the production rate of 1O2 but was cancelled by exogenous applications of the phytohormone jasmonate. OXI1-mediated 1O2 signaling appeared to operate through a different pathway from the previously characterized OXI1-dependent response to pathogens and H2O2 and was found to be independent of the EXECUTER proteins. In high-light-stressed plants, the oxi1 mutation was associated with reduced jasmonate levels and with the up-regulation of genes encoding negative regulators of jasmonate signaling and PCD. Our results show that OXI1 is a new regulator of 1O2induced PCD, likely acting upstream of jasmonate.

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