Receptor-like kinase-mediated cell wall integrity signaling in plant environmental stress responses.

Receptor-like kinases (RLKs) serve as central signaling hubs that integrate extracellular signals with intracellular responses to maintain cell wall integrity and cellular homeostasis. Their structural and functional diversity enables precise perception of developmental, immune, and environmental cues. Recent advances in structural biology, phosphoproteomics, and genome engineering have substantially deepened our understanding of RLK function and regulation. Harnessing this knowledge offers promising opportunities to engineer crops with enhanced resilience to biotic and abiotic stresses, contributing to sustainable agriculture under a changing climate. Plants are continually exposed to mechanical, osmotic, and biotic stresses that threaten cell wall integrity and cellular homeostasis. Receptor-like kinases (RLKs) represent one of the largest families of plasma membrane receptors and function as key sensors that connect extracellular cues with intracellular signaling networks. Positioned at the cell wall-plasma membrane interface, RLKs perceive diverse signals, including microbe-associated molecular patterns (MAMPs), damage-associated molecular patterns (DAMPs), endogenous peptides, and changes in cell wall architecture. Major RLK subfamilies, including leucine-rich repeat RLKs (LRR-RLKs), lysin motif RLKs (LysM-RLKs), Catharanthus roseus RLK1-like kinases (CrRLKs), and wall-associated kinases (WAKs), have evolved specialized ligand-recognition mechanisms that enable signaling specificity and functional diversity. Following activation, RLKs assemble dynamic receptor complexes that initiate phosphorylation cascades involving mitogen-activated protein kinases, calcium-dependent signaling pathways, reactive oxygen species (ROS) production, and hormonal regulators. These interconnected networks integrate developmental processes with immune and abiotic stress responses, allowing plants to coordinate growth, defense, and environmental stress adaptation. Recent advances in structural biology, phosphoproteomics, and genome engineering have expanded understanding of RLK-mediated signaling and revealed opportunities for crop improvement. Here, the review synthesizes current knowledge of RLK structural diversity, signal transduction mechanisms, and network integration, highlighting their central role in cell wall integrity surveillance, stress adaptation, and emerging strategies for engineering climate-resilient crops.