Plant cell surface receptors.

Plants face constant environmental changes and must integrate external and internal cues to coordinate growth, development, reproduction, and stress responses. A major strategy is perception at the cell surface via a large, diverse network of receptors. Here, we outline how these receptors recognise extracellular signals and assemble active complexes with appropriate co-receptors. Diverse ectodomain structures enable the recognition of peptides and proteins, glycans, lipids, phytohormones, and other small molecules, as well as changes in cell wall status. We then summarise the downstream pathways, highlighting how cytosolic kinase domains couple to receptor-like cytoplasmic kinases, MAPK modules and other signalling components, and how timing, partner choice, and cellular context confer specificity to produce distinct physiological outputs across diverse processes. Finally, we discuss the origin and evolution of cell surface receptors. Receptor-like kinases share a single origin and significantly diversified around the emergence of land plants to support new functions. Together, this perception system repeatedly adapted to new roles and point to opportunities to reprogramme cell surface receptors for resilience and crop improvement.