Abstract
Effects of N-cyanomethyl-2-chloroisonicotinamide (NCI) on respiration, lipid metabolism, polyamine biosynthetic enzymes, and activities of lipoxigenase (LOX) and peroxidase (POX) in rice plants were investigated in terms of resistance against rice blast disease. The respiration in glycolytic process which supplies NADPH was stimulated by submerged application of NCI in compatible plants inoculated with P. oryzae, whereas the respiration related to TCA cycle which is represented by oxidation of acetate was not affected. Incorporation of [2-14C] acetate into lipids was enhanced remarkably in the NCI-treated, inoculated plants at 36hr after infection. Activities of ornithine decarboxylase (ODC) and S-adenosyl-methionine decarboxylase (SAMDC) were suppressed about 50% in inoculated plants, whereas such suppression was not observed in NCI treated plants. No remarkable change in ODC and SAMDC activities may account for steady resistance of the plants against the invading pathogens. The activities of LOX and POX were significantly augmented by infection of NCI-treated plants, which appeared to be shifted to an incompatible variety. These results indicate that NCI has a priming effect related to the resistant reaction of rice plants to the pathogen.
