A phosphorylation-dependent ubiquitination switch orchestrates nuclear immune reprogramming upon chitin perception.

The 14-3-3 proteins, a highly conserved class in all eukaryotes, are widely associated with plant growth and stress responses. However, their role in plant immunity and its regulatory mechanisms remains elusive. Here, we show that two homologous rice 14-3-3 proteins, OsGF14f and OsGF14c, function redundantly to enhance rice resistance against Magnaporthe oryzae. The E3 ligase OsPUB20 targets OsGF14f and OsGF14c for ubiquitination and 26S proteasome-mediated degradation, thereby negatively regulating rice immunity. Remarkably, chitin perception activates the receptor-like cytoplasmic kinase OsRLCK185 that phosphorylates OsPUB20 at Thr153, which stabilizes OsGF14f and enhances rice blast resistance. Furthermore, during M. oryzae infection, OsGF14f translocates into the nucleus, where it facilitates the degradation of OsWRKY42, a transcription factor that negatively regulates defense responses. Collectively, our findings reveal a phosphorylation-dependent ubiquitination switch that links cell surface chitin perception to nuclear immune reprogramming during M. oryzae invasion.