The glycosylated root‐knot nematode effector Minc10750 suppresses plant immunity by destabilizing host chitinases

Abstract

Root‐knot nematodes (Meloidogyne spp.) secrete effectors that suppress plant immunity; however, the mechanisms by which they counteract specific defense enzymes, such as chitinases, remain unclear. In this study, we demonstrate that the Meloidogyne incognita effector Minc10750 directly targets the catalytic domain of plant chitinases (Chi), serving as a critical determinant of virulence. The expression of Minc10750 is upregulated in the subventral esophageal glands during early infection. Its binding to the glycosyl hydrolase 19 domain of chitinases is strictly dependent on effector N‐glycosylation. A mutation at the asparagine glycosylation site (Minc10750‐Mu3) abolishes this modification, impairs its nuclear accumulation, and disrupts the interaction. Mechanistically, Minc10750 promotes the proteasome‐dependent destabilization of Chi proteins, thereby suppressing Chi‐triggered immunity, including mitogen‑activated protein kinase (MAPK) activation and reactive oxygen species burst. Consistently, Chi mutants exhibit enhanced susceptibility to nematodes, whereas Chi overexpression confers resistance. Transcriptome analysis further reveals that the Chi‐mediated expression of defense‐related transcription factors is compromised in Minc10750 transgenic plants. Our findings elucidate a mechanism by which a glycosylated nematode effector disables a core component of basal immunity, thereby providing a potential target for the engineering of nematode‐resistant crops.