Perception of a bacterial quorum sensing signal activates a tripartite plant immune strategy.

Abstract

Bacterial quorum sensing (QS) signals an increasing threat during pathogenesis. How plants deploy timely defenses through QS perception is poorly understood. Here, we report that <i>Arabidopsis thaliana</i> perceives 2'-aminoacetophenone (2'-AA), a volatile QS signal from <i><i>Pseudomonas aeruginosa</i></i>, and mounts a multilayered defense. This response comprises BRI1-ASSOCIATED RECEPTOR KINASE 1 (BAK1)-dependent intracellular immunity, extracellular quorum quenching through the release of acetic acid, and ecological remodeling of the root microbiome to suppress <i><i>Pseudomonas</i></i>. Our findings demonstrate that plants can translate the detection of a specific bacterial QS molecule into a coordinated, preemptive disease resistance strategy.