MoSec61γ Links ER Homeostasis and Autophagic Control to Appressorium Function and Host Immune Evasion in Magnaporthe...

MoSec61γ, the γ subunit of the ER translocon, was essential for protein translocation and cellular homeostasis. In Magnaporthe oryzae, deletion of MoSEC61γ caused severe defects in appressorium development and function, resulting in markedly reduced virulence. The mutant exhibited impaired turgor generation, abnormal morphology, and diminished host penetration, accompanied by reduced phosphorylation of the MAP kinases Pmk1 and Mps1. Moreover, ΔMosec61γ failed to suppress host immunity and showed defective secretion of apoplastic effectors, while cytoplasmic effectors remained unaffected. Mechanistically, MoSec61γ maintained ER integrity, prevented excessive ER-phagy and nonselective autophagy, and ensured efficient ER-Golgi trafficking. Its loss induced ER stress, attenuated UPR signaling, and led to constitutive autophagic activity, ultimately disrupting effector trafficking and pathogenic development. These findings established MoSec61γ as a central regulator linking ER homeostasis, autophagy, effector secretion, and infection-related morphogenesis in M. oryzae.