Cerebroside elicitors found in diverse phytopathogens activate defense responses in rice plants

Cerebrosides A and C, compounds categorized as glycosphingolipids, were iso lated in our previous study from the rice blast fungus (Magnaporthe grisea) as novel elicitors which induce the synthesis of rice phytoalexins. In thi s paper, these cerebroside elicitors showed phytoalexin-inducing activity w hen applied to plants by spray treatment and also induced the expression of pathogenesis-related (PR) proteins in rice leaves. This elicitor activity of the cerebrosides showed the structural specificity as that for the induc tion of phytoalexins, Ceramides prepared from the cerebrosides by removal o f glucose also showed the elicitor activity even in lower level compared to the cerebrosides, In field experiments, the cerebroside elicitors effectiv ely protected rice plants against the rice blast fungus, an economically de vastating agent of disease of rice in Japan. The cerebrosides elicitors pro tected rice plants from other disease as well and were found to occur in a wide range of different phytopathogens, indicating that cerebrosides functi on as general elicitors in a wide variety of rice-pathogen interactions.