Effects of salicylic and jasmonic acid on phospholipase D activity and the level of active oxygen species in soybean seedlings

Plant cell metabolism reactions upon biotic stress conditions are initiated via cellular signaling systems. At the same time, signaling pathways of phytohormonal mediators of biotic stress induction, salicylic acid and jasmonic acid, and their intracellular activities are implemented in cooperation with lipid-derived regulatory elements. In this work we have found that salicylic acid treatment evoke activation of phospholipase D responsible for the production of second messenger phosphatidic acid. Mediators of the defense reactions also affected the balance of active oxygen species and in particular induced accumulation of endogenous hydrogen peroxide and changes in the activities of antioxidant enzymes (catalase, peroxidases, and superoxide dismutase). Our results point out to the interactions between lipid signaling enzymes and cellular antioxidant systems required for realization of primary adaptation responses to biotic stress mediators in plants.