N-acetylchitooligosaccharides elicit rice defence responses including hypersensitive response-like cell death, oxidative burst and defence gene expression
2004
Ning, W. | Chen, F. | Mao, B. | Li, Q. | Liu, Z. | Guo, Z. | He, Z.
Rice, a monocotyledonous model plant, can be used to dissect the molecular mechanism of plant defence activation in cereal crops. In the present work, we investigated acetylchitooligosaccharide (COS)-mediated defence activation in rice. COS strongly induced cell death and defence gene expression in rice suspension cells in a dose- and degree of polymerization-dependent manner. COS treatment could also induce visible cell death on rice leaves. Rapid production of H2O2 was observed preceding cell death in the COS-stimulated rice cells. The H2O2 generation and consequential cell death could be blocked by diphenylene iodonium, indicating that the COS-mediated oxidative burst depends on an NADPH oxidase. The rice defence-related genes, RCH10 and PAL were strongly induced by COS, and OsCatB was first repressed and then induced by COS. Consequentially, rice disease resistance was enhanced by COS against the blast fungus. Taken together, these results strongly suggested that COS activates the rice defence responses via a mechanism similar to the hypersensitive response involved in the plant-microbe interactions. Our study shows the feasibility of this system to dissect elicitor-mediated activation of non-specific defence in rice.
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