Recognition of a phytocytokine by the DEPR1-SERK2 receptor complex confers multi-pathogen resistance in wheat

The recognition of plant-derived immunogenic peptides, known as phytocytokines (PCKs), by cell surface receptors triggers immune signaling pathways that bolster basal plant defense against pathogens. However, little is known about the molecular mechanisms that underlie PCK-mediated immune regulation in wheat. In this study, we identified a wheat PCK, delta-like PCK (DEP), that robustly activates immune responses and confers multi-pathogen resistance. DEP is perceived by the leucine-rich repeat (LRR) receptor kinases (RKs) DEP RECEPTOR 1 (DEPR1) and SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE 2 (SERK2) and triggers DEPR1- and SERK2-dependent immune signaling. Cryogenic electron microscopy structural analysis revealed that DEP2 binds to the extracellular LRR domain of DEPR1 and recruits SERK2 through a disulfide-bond-stabilized loop to promote DEPR1-SERK2 heterodimerization. Furthermore, we showed that the DEP2-DEPR1-SERK2 module confers wheat resistance to Xanthomonas translucens, Fusarium graminearum, and Fusarium pseudograminearum. We also demonstrated that this module enhances wheat resistance to X. translucens by antagonizing abscisic acid signaling. Collectively, our study reveals a novel PCK-mediated immune signaling pathway and suggests a promising strategy for engineering multi-pathogen resistance in wheat.