Heterologous Overexpression of Magnaporthe oryzae Effector PWL2 Enhances Rice Blast Resistance via SA-Mediated and PWL2-Derived siRNA Defense.

Fungal effectors play an important role in plant immunity. The Magnaporthe oryzae effector PWL2 plays a significant role in rice blast disease caused by this fungus. However, the function of PWL2 in rice immunity is not fully understood. In this study, transgenic rice lines overexpressing PWL2 showed resistance to rice blast. Subcellular localization showed that PWL2-GFP fusion protein is localized on the plasma membrane and cytoplasm. Salicylic acid (SA) induces rice resistance to M. oryzae. Notably, the expression of the NPR1 gene exhibited a rhythmic pattern during the early stages of M. oryzae infection in the transgenic rice lines. However, during later stages of infection, transgenic plants showed reduced levels of the NPR1, WRKY45, PR1a and PR10a genes, along with decreased H2O2 accumulation, while SA levels remained unchanged. Transcriptome analysis revealed that SA treatment induced the expression of the ARGONAUTE11 (AGO11) gene in rice. Furthermore, during the later infection stage in the transgenic rice lines, the expression levels of both AGO11 and PWL2 genes increased. Intriguingly, PWL2-derived small interfering RNAs (siRNA) were detected in these transgenic rice lines. It suggests that both the SA signaling pathway and PWL2-derived siRNAs function in rice resistance to blast disease caused by M. oryzae.