Functional characterization of MoHym1 in governing pathogenicity and conferring resistance to DNA damage drugs in Magnaporthe oryzae.

BACKGROUND: The rice blast fungus, Magnaporthe oryzae, poses a serious threat to global rice production. Cell cycle and polarized growth are two essential processes for host infection of M. oryzae; however, the association of them remains largely unknown. RESULTS: MoHym1, a homolog of yeast RAM (regulation of Ace2 and morphogenesis) network component, was identified as a key regulator for fungal development and pathogenicity in M. oryzae. Deletion of MoHYM1 resulted in severe defects in vegetative growth, conidiation, polarized growth, cell wall integrity, surface hydrophobicity, and secretion of virulence-associated enzymes, which are essential prerequisites for effective host infection. Furthermore, disruption of MoHYM1 led to abnormal nuclear division and disrupted cell cycle progression while also increasing resistance to DNA-damaging agents hydroxyurea and bleomycin. Yeast-two-hybrid screening revealed interactions with proteins related to adenosine triphosphate (ATP) synthesis. CONCLUSION: These results position MoHym1 as a multifunctional coordinator of development, cell cycle, and virulence, thereby providing a new target for the control of rice blast. © 2026 Society of Chemical Industry.