Activation of ethylene signaling pathways enhances disease resistance by regulating ROS and phytoalexin production in rice
C. YANG (1) (1) State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, China

Ethylene plays diverse roles in plant growth, development, and stress responses. However, it is unclear how ethylene signaling acts during immune responses. In order to validate the roles of ethylene signaling in plant immune response, we have shown that the blast fungus Magnaporthe oryzae activated ethylene biosynthesis in rice. Notably, resistant rice cultivars accumulated higher levels of ethylene than susceptible ones. Ethylene signaling components OsEIN2 and OsEIL1 positively regulated disease resistance. Mutation of OsEIN2 significantly enhanced disease susceptibility. Whole-genome transcription analysis revealed that responsive genes for ethylene, jasmonates (JAs), and reactive oxygen species (ROS) as well as phytoalexin biosynthesis genes were remarkably induced. We found that OsrbohA/B, which encodes NADPH oxidase, and OsOPRs, the JA biosynthesis genes, were induced by M. oryzae infection. Further, we demonstrated that OsEIL1 binds to the promoters of OsrbohA/OsrbohB and OsOPR4 to activate their expression. Rice plants overexpressing OsEIN2 showed JA and phytoalexin accumulation in the leaves. These data suggest that OsEIN2-mediated induction of OsOPR transcription may result in JA biosynthesis and, subsequently, phytoalexin accumulation. Because ROS and phytoalexins play key roles in restricting M. oryzae infection, we suggest that M. oryzae invasion activates ethylene signaling, leading to the production of ROS and phytoalexins in infected rice cells and resistance to M. oryzae.

Abstract Number: P16-480
Session Type: Poster