A plasma membrane receptor complex mediates early heat-responsive signaling to trigger nuclear transcriptomic...

The plasma membrane has been proposed as a primary site for temperature sensing in plants, but the molecular mechanism that links external heat signals to intracellular responses remains elusive. Here, we identify a membrane-anchored receptor complex composed of BARELY ANY MERISTEM 1 (BAM1) and AVRPPHB SUSCEPTIBLE 1 (PBS1) that orchestrates rapid heat-signal transduction. Upon heat stress, BAM1 is rapidly activated within seconds and associates with PBS1, which in turn triggers RBOHD-dependent H₂O₂ production. This H₂O₂ signal is directly decoded by the heat-shock factor HSFA1b, leading to its oxidation, increased protein stability, and nuclear accumulation, thereby driving heat-responsive transcriptional reprogramming. Furthermore, the secreted peptide CLAVATA3/EMBRYO SURROUNDING REGION-related 40 (CLE40) amplifies the heat response by promoting BAM1 activation and enhancing formation of the BAM1-PBS1 complex. Taken together, these findings reveal that a membrane complex constitutes an early and contributing pathway in the relay of heat signals from the membrane to the nucleus.