Molecular mechanisms of early plant pattern-triggered immune signaling

• Published in: Molecular cell 2021-09, Vol.81 (17), p.3449-3467
• Main Authors: DeFalco, Thomas A., Zipfel, Cyril
• Format: Article
• Language: English
• ISSN: 1097-2765; 1097-4164
• DOI: 10.1016/j.molcel.2021.07.029

All eukaryotic organisms have evolved sophisticated immune systems to appropriately respond to biotic stresses. In plants and animals, a key part of this immune system is pattern recognition receptors (PRRs). Plant PRRs are cell-surface-localized receptor kinases (RKs) or receptor proteins (RPs) that sense microbe- or self-derived molecular patterns to regulate pattern-triggered immunity (PTI), a robust form of antimicrobial immunity. Remarkable progress has been made in understanding how PRRs perceive their ligands, form active protein complexes, initiate cell signaling, and ultimately coordinate the cellular reprogramming that leads to PTI. Here, we discuss the critical roles of PRR complex formation and phosphorylation in activating PTI signaling, as well as the emerging paradigm in which receptor-like cytoplasmic kinases (RLCKs) act as executors of signaling downstream of PRR activation. Plants possess a sophisticated multilayered immune system. DeFalco and Zipfel review the molecular mechanisms underpinning early immune signaling mediated by cell-surface pattern recognition receptors, with an emphasis on the roles of heteromeric protein complexes and phosphorylation in the activation and regulation of immune responses.