Decursin, Identified via High‐Throughput Chemical Screening, Enhances Plant Disease Resistance via Two Independent Mechanisms

ABSTRACT In order to overcome the damage caused by phytopathogens, plants have evolved a complex defence system to protect themselves, such as the two‐tiered innate immunity system. Chemical screening has led to the identification of plant immune‐priming compounds, which facilitate the functional dissection of the plant immune system and contribute to chemical control for plant diseases. In this study, we identified decursin, a coumarin natural product, through high‐throughput screening for activators of the expression of FLG22‐INDUCED RECEPTOR KINASE 1 ( FRK1 ). Decursin functions as a typical immune elicitor, triggering early immune responses, including a reactive oxygen species (ROS) burst, MAPK activation, and transcriptional reprogramming of defence genes. A targeted reverse genetic approach identified CERK1, a lysin motif receptor‐like kinase (LysM‐RLK), loss of function of which resulted in a significant reduction of decursin‐induced immune responses. Moreover, decursin was demonstrated to be ineffective in eliciting immune activation in the lyk4 lyk5 mutant, a double mutant of two additional LysM‐RLKs. Molecular docking studies predicted that decursin may bind to CERK1 and LYK5. Decursin has been demonstrated to possess potent antiphytopathogenic properties, exhibiting pronounced growth inhibitory effects against several important plant fungal pathogens in vitro and in vivo, thereby protecting plants from damage caused by these pathogens. It can be concluded that decursin exerts its function through two independent mechanisms to enhance plant disease resistance, providing a potent agrochemical in disease control.