The role of lipid peroxidation and lipoxygenase in the non-host disease resistance of rice

Rice leaf sheaths inoculated with Rhizoctonia solani (pathogen) and Pestalotia palmarum (non-pathogen) were analyzed for the induction of lipid peroxidation and lipoxygenase (LOX) activity. In incompatible interaction, the level of lipid peroxidation significantly increased 1 day after inoculation and reached the maximum 3 days after inoculation. A twofold increase in lipid peroxidation was observed 3 days after inoculation with P. palmarum. In contrast, in the compatible interaction significant increase in the level of lipid peroxidation was not observed until 3 days after inoculation. LOX activity also rapidly increased in rice leaf sheaths after inoculation with the non-pathogen. Inoculation of P. palmarum increased the LOX activity by 18 % above control levels by 3 day, while R. solani caused only 8 % increase. The present study provides evidence for the important role of lipid peroxidation in the non-host resistance of rice.