FERONIA orchestrates plasma membrane nanoclusters for plant thermotolerance.

Climate warming poses increasing thermal challenges to plants, yet how plasma membrane biophysics contributes to heat adaptation remains poorly understood. In this work, we showed that the malectin-like receptor kinase FERONIA (FER) acts as a membrane-anchored thermal switch in Arabidopsis. FER organizes sterol-dependent nanoclusters that control heat acclimation. Moderate heat activated FER through the RAPID ALKALINIZATION FACTOR 34 (RALF34) peptide and promoted its recruitment to sterol-rich nanodomains. There, FER nucleated dynamic nanoclusters enriched in stress-signaling components. These nanoclusters stabilized liquid-ordered membrane phases and activated heat shock transcription factor-heat shock protein signaling, enhancing thermotolerance. However, under extreme heat the nanoclusters rapidly disassembled, preventing maladaptive responses. Our findings thus establish nanoscale membrane compartmentalization as a key mechanism linking lipid dynamics to plant thermal resilience.