Resistance-related defense enzymes and endogenous salicylic acid induced by exogenous methyl jasmonate in rice against blast disease.

Methyl jasmonate(MeJA)is important signaling hormones in plants,known to play a role in developmental processes and in induced defense responses.Exogenous MeJA significantly increased disease resistance of rice against rice blast,but no inhibitory effect was detected on spore germination and mycelium growth of Magnaporthe grisea in vitro.Therefore,the reduction of disease severity in MeJA-treated rice plants was due to MeJA-induced resistance to blast.After treatment with MeJA,changes in LOX,PAL,POD and CAT activities increased significantly compared with those in contro1.Compared with the compatible rice line,CO39,the activities of four enzymes increased more remarkably and rapidly in the leaves of the incompatible rice line C101LAC.PR proteins were possessed defining characteristic of systemic acquired resistance(SAR)in plants.The results showed that changes in two pathogenesis-related proteins(PR proteins),chitinase and β-1,3-glucanase,were also increased more remarkably and rapidly in the leaves of the incompatible rice line than that of compatible rice line.Our results also showed that endogenous SA had little change either in the leaves of incompatible rice line or compatible line.The results suggested that defense-related enzymes and SAR in rice leaves induced by MeJA might play an important role in resistance to rice blast.