Coordinated Activation of Metabolic Pathways for Antioxidants and Defence Compounds by Jasmonates and their Roles in Stress Tolerance in Arabidopsis

Abstract

Jasmonic acid (JA) is ubiquitous plant signaling compound in stress conditions. Although jasmonates are important signaling components, the mechanism by which jasmonate signaling contributes to stress tolerance has not been clearly defined. A comprehensive analysis of jasmonate regulated metabolic pathways in Arabidopsis was performed using cDNA macroarrays covering 8384 loci. We showed that jasmonates activate ascorbate and glutathione metabolic pathways, which are important in defense responses to oxidative stress. These antioxidant metabolic pathways are known to be activated under oxidative stress conditions. We showed that O₃ exposure, a representative oxidative stress, caused the induction of several genes involved in antioxidant metabolism in the wild type. However, in jasmonate-deficient opr3 mutants, the induction of antioxidant genes was abolished. Compared with the wild type, opr3 mutants were more sensitive to O₃ exposure. These results suggest that the coordinated activation of the metabolic pathways mediated by jasmonates provides resistance to environmental stresses.