A Lectin Receptor-Like Kinase Mediates Pattern-Triggered Salicylic Acid Signaling

Abstract

Plant surface-localized pathogen recognition receptors (PRRs) perceive conserved microbial features, termed pathogen-associated molecular patterns (PAMPs), resulting in disease resistance. PAMP perception leads to calcium influx, MAPK activation, a burst of reactive oxygen species (ROS) mediated by RbohD, accumulation of the defense hormone salicylic acid (SA), and callose deposition. Lectin receptor-like kinases (LecRKs) belong to a specific PRR family and are important players in plant innate immunity. Here, we report that LecRK-IX.2 is a positive regulator of PRR-triggered immunity. Pathogen infection activated the transcription of Arabidopsis (<i>Arabidopsis thaliana</i>) <i>LecRK-IX.2</i>, and the <i>LecRK-IX.2</i> knockout lines exhibited enhanced susceptibility to virulent <i>Pseudomonas syringae</i> pv <i>tomato</i> DC3000. In addition, LecRK-IX.2 is capable of inducing RbohD phosphorylation, likely by recruiting calcium-dependent protein kinases to trigger ROS production in Arabidopsis. Overexpression of <i>LecRK-IX.2</i> resulted in elevated ROS and SA and enhanced systemic acquired resistance to <i>P. syringae</i> pv <i>tomato</i> DC3000. Our data highlight the importance of LecRKs in plant immune signaling and SA accumulation.