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

Abstract

The recognition of plant-derived immunogenic peptides, known as phytocytokines (PCKs), with cell surface-resident receptors triggers immune signaling pathways that bolster the plant's basal defense against pathogens. However, the molecular mechanism underlying PCK-mediated immune regulation in wheat remains largely unexplored. In this study, we identified a wheat PCK, Delta-like PCK (DEP), which robustly activates immune responses and confers multi-pathogen resistance in wheat. 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 DERP1- and SERK2-dependent immune signaling. Cryogenic electron microscopy (cryo-EM) 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 disease 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 (ABA) signaling. This work elucidates a novel phytocytokine-mediated immune signaling pathway and provides a promising strategy for inducing multi-pathogen resistance in wheat.