Mechanism of action of salicylic acid during defense response of plant

Salicylic acid (SA) has been reported as an endogenous signal for the activation of certain plant defense responses, including pathogenesis related gene expression and enhanced resistance to pathogens. In our previous investigation we have observed that exogenous application of salicylic acid induced the expression of pathogenesis related -1 (PR-1) gene in okra and cowpea and enhanced resistance against Meloidogyne incognita. Here the interaction of SAand the rat livermicrosomal membrane was investigated in the presence and absence of catalase. Our result showed that though catalase and salicylic acid have no effect on lipid peroxidation but catalase significantly increased SA induced lipid peroxidation of rat liver microsomal membrane. The result suggests that salicylic acid may form SA free radicals upon interaction with catalase. Such free radicals induce lipid peroxidation, and the products of this reaction, may activate plant defense responses.