A light-responsive transcriptional circuit suppresses sexual reproduction in the rice blast fungus in the field

Magnaporthe oryzae, the causal agent of rice blast disease, reproduces asexually in nature but can reproduce sexually under artificial continuous light. How environmental cues regulate this developmental balance has long been unclear. Here, we identified a light-responsive MoNFYB-MoRAN1-MoPHO1 transcriptional circuit regulating this switch. Light induces the transcriptional repressor MoNFYB, which binds the Moran1 promoter, displaces MoTFIIB, and represses Moran1 expression. This suppresses conidiation and virulence while promoting perithecium formation. MoRAN1 phosphorylates the phosphatase MoPHO1 to enhance phosphate acquisition. Disruption of Mopho1 reduced phosphate assimilation and phenocopied Moran1 deletion. Thus, light or phosphate limitation suppresses the MoRAN1-MoPHO1 module, shifting development toward sexual reproduction. Our findings explain the fungus's failure to mate in rice fields and identify phosphate metabolism as a potential target for disease management.