An apoplastic fungal effector disrupts N-glycosylation of ZmLecRK1, inducing its degradation to suppress disease resistance in maize

Abstract

Pathogens deploy effectors to suppress host immune responses and enable successful colonization in plants. While apoplastic effectors have major roles in pathogenicity, whether and how they directly attack extracellular immune receptors remains unclear. Here we identify an apoplastic effector FgLPMO9A from the fungal pathogen Fusarium graminearum that directly inhibits maize immune receptor ZmLecRK1-mediated resistance. FgLPMO9A belongs to the polysaccharide monooxygenase family, which depolymerizes polysaccharides. Deletion of FgLPMO9A attenuates F. graminearum virulence on maize, but this defect is fully rescued in the zmlecrk1 mutants. FgLPMO9A interacts with the extracellular S-domain of ZmLecRK1 and disrupts N-glycosylation at the N341 site, thereby promoting ZmLecRK1 degradation via the NBR1-mediated autophagy pathway. Notably, the ZmLecRK1 variant with the N341Q substitution confers enhanced resistance to F. graminearum in maize. We demonstrate that F. graminearum dampens maize immunity by deploying an apoplastic effector to induce extracellular immune receptor degradation.