A Core Effector MoPce1 Is Required for the Pathogenicity of Magnaporthe oryzae by Modulating Catalase‐Mediated H 2 O 2 Homeostasis in Rice

ABSTRACT Plant pathogens employ a diverse array of effectors to facilitate host colonisation, including evolutionarily conserved core effectors. In this study, we identified MoPce1, a CAP/PR‐1 domain‐containing protein widely distributed among fungal species, as a key virulence factor in Magnaporthe oryzae . Among 72 putative core effectors (PCEs), MoPce1 was found to be essential for pathogenicity but dispensable for asexual development. It localises to biotrophic interfacial complex (BIC) in invasive hyphae (IHs) and to the cytoplasm in Nicotiana benthamiana leaves and rice protoplasts. Ectopic expression of a signal peptide‐deleted variant of MoPCE1 ( MoPCE1 Δsp ) in rice compromised blast resistance and suppressed the reactive oxygen species (ROS) burst. Notably, MoPce1 lacks the conserved cysteine residues essential for sterol‐binding in the CAP domain, suggesting its potential association with a novel ligand. Further investigation revealed that MoPce1 interacts with rice catalase OsCATC, specifically via the C1 fragment (231–360 aa). Disruption of OsCATC ( oscatc ) enhanced rice blast resistance and triggered a stronger ROS burst. Collectively, our results indicate that MoPce1 targets OsCATC to disrupt ROS homeostasis and suppress host immunity, thereby facilitating infection.