Osa‐miR164a targets OsNAC60 and negatively regulates rice immunity against the blast fungus Magnaporthe oryzae

Summary Exploring the regulatory mechanism played by endogenous rice mi RNA s in defense responses against the blast disease is of great significance in both resistant variety breeding and disease control management. We identified rice defense‐related mi RNA s by comparing rice mi RNA expression patterns before and after Magnaporthe oryzae strain Guy11 infection. We discovered that osa‐miR164a expression reduced upon Guy11 infection at both early and late stages, which was perfectly associated with the induced expression of its target gene, Os NAC 60 . Os NAC 60 encodes a transcription factor, over‐expression of which enhanced defense responses, such as increased programmed cell death, greater ion leakage, more reactive oxygen species accumulation and callose deposition, and upregulation of defense‐related genes. By using transgenic rice over‐expressing osa‐miR164a, and a transposon insertion mutant of Os NAC 60 , we showed that when the miR164a/ Os NAC 60 regulatory module was dysfunctional, rice developed significant susceptibility to Guy11 infection. The co‐expression of Os NAC 60 and osa‐miR164a abolished the Os NAC 60 activity, but not its synonymous mutant. We further validated that this regulatory module is conserved in plant resistance to multiple plant diseases, such as the rice sheath blight, tomato late blight, and soybean root and stem rot diseases. Our results demonstrate that the miR164a/ Os NAC 60 regulatory module manipulates rice defense responses to M. oryzae infection. This discovery is of great potential for resistant variety breeding and disease control to a broad spectrum of pathogens in the future.