Cysteine-rich receptor-like kinases mediate Wall Teichoic Acid perception in Arabidopsis

Plants and animals detect microbe-associated molecular patterns (MAMPs) to initiate defense responses. Both lineages employ pattern recognition receptors (PRRs), yet plant mechanisms for sensing Gram-positive bacterial MAMPs remain poorly understood. Wall teichoic acids (WTAs), anionic glycopolymers unique to Gram-positive bacteria, are shown here to activate salicylic acid signaling, defense priming, and a non-canonical programmed cell death in Arabidopsis . We demonstrate that glycosylated WTAs from diverse Gram-positive species elicit these responses and provide genetic evidence that their recognition depends on two members of the plant-specific CYSTEINE-RICH RECEPTOR-LIKE KINASE (CRK) gene family, which is absent in animals and whose function remains elusive. These findings reveal WTAs as a novel class of MAMPs in plants and highlight CRKs as key components in their perception.