Histone Demethylase MoRph1 Regulates Fungal Development, Pathogenicity, and DNA Damage Repair in Magnaporthe oryzae

Histone demethylases regulate epigenetic modifications and DNA damage repair in fungal pathogens, yet their specific functions in Magnaporthe oryzae remain poorly understood. This study identifies MoRph1, a JmjC domain-containing histone demethylase that interacts with the COMPASS complex. Targeted deletion of MoRph1 resulted in significantly reduced vegetative growth, impaired conidiation, and defective appressorium formation. The mutant displayed compromised appressorial turgor pressure due to delayed degradation of glycogen and lipid reserves, leading to inefficient host penetration and attenuated virulence on rice and barley. MoRph1 localized to the nucleus, and its absence caused increased nuclear abnormalities under DNA damage stress, suggesting impaired genome stability maintenance. Biochemical analysis confirmed that MoRph1 specifically demethylates histone H3 lysine 36 trimethylation. Transcriptome analysis revealed altered expression of genes associated with DNA replication, mismatch repair, and oxidative stress response. These results establish MoRph1 as a crucial epigenetic regulator coordinating fungal development, infection structure function, energy mobilization, and DNA damage repair. This study underscores the importance of chromatin-level regulation in fungal pathogenicity and provides a foundation for future evaluation of MoRph1 as a potential antifungal target.