A Conserved Magnaporthe oryzae Effector Counteracts the Rice Ubiquitin-Proteasome System by Disrupting the E2...

Pathogens commonly secrete effectors into host cells to facilitate invasion. In the host ubiquitin-proteasome system (UPS), E3 ubiquitin ligases often target pathogen effectors for degradation, thereby enhancing immune responses. In turn, pathogen effectors frequently disrupt E3 ligase function to promote virulence. However, it remains largely unclear whether pathogen effectors also interfere with other enzymes of the UPS, such as E2 ubiquitin-conjugating enzymes. In this study, we identified a conserved effector, MoCE1, that is essential for the pathogenicity of Magnaporthe oryzae. MoCE1 is secreted into rice cells, where it interacts with the rice E3 ligase OsRING10 and the E2 enzyme OsUBC11. Upon M. oryzae infection, OsRING10 and OsUBC11 act synergistically to degrade MoCE1 through K48-linked polyubiquitination. Overexpression of either OsRING10 or OsUBC11 enhances resistance to M. oryzae. To counteract this defence, MoCE1 inhibits the enzymatic activity of OsUBC11. Collectively, these findings reveal a nuanced mechanism in which a pathogen effector, regulated by a host E2-E3 pair, disrupts E2 function to escape UPS-mediated immunity in plants.