The E3 ubiquitin ligase OsRGLG5 targeted by the Magnaporthe oryzae effector AvrPi9 confers basal resistance against rice blast

Rice blast, caused by Magnaporthe oryzae, is one of the most devastating diseases of rice. During infection, M. oryzae secretes effectors to facilitate blast development. Among these effectors, the avirulence factor AvrPi9 is recognized by Pi9, a broad-spectrum blast resistance protein that triggers Pi9-mediated resis-tance in rice. However, little is known about the interaction between AvrPi9 and Pi9 and how AvrPi9 exerts virulence to promote infection. In this study, we found that ectopic expression of AvrPi9 in the Pi9-lacking cultivar TP309 suppressed basal resistance against M. oryzae. Furthermore, we identified an AvrPi9-interacting protein in rice, which we named OsRGLG5, encoding a functional RING-type E3 ubiquitin ligase. During infection, AvrPi9 was ubiquitinated and degraded by OsRGLG5. Meanwhile, AvrPi9 affected the sta-bility of OsRGLG5. Infection assays revealed that OsRGLG5 is a positive regulator of basal resistance against M. oryzae, but it is not essential for Pi9-mediated blast resistance in rice. In conclusion, our results revealed that OsRGLG5 is targeted by the M. oryzae effector AvrPi9 and positively regulates basal resistance against rice blast.

Automated summary

Rice blast, caused by Magnaporthe oryzae, is a devastating disease that affects rice. This study investigates the interaction between the avirulence factor AvrPi9 and the resistance protein Pi9 in rice, as well as the role of AvrPi9 in promoting infection. The researchers found that AvrPi9 suppresses basal resistance against M. oryzae when expressed in a cultivar lacking Pi9. They also identified a protein named OsRGLG5 that interacts with AvrPi9 and positively regulates basal resistance against rice blast. This study provides insights into the mechanisms of rice resistance against blast and highlights the importance of understanding the interaction between pathogens and host plants.