Oxygen and redox regulation of plant thermomorphogenesis.

Plant thermomorphogenesis represents the adjustment of growth to warm ambient temperatures. The mechanism has long been organised around the transcription factor PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) and the thermosensors that act upon it. Internal circadian control and external light intensity and quality have been the primary contexts that gate thermosensor-PIF signal transduction. Here, we argue that cellular oxygen and the reduction/oxidation (redox) state of the cell form additional layers that gate or calibrate thermosensing signal transduction. Current evidence points to discrete mechanisms across spatial or developmental contexts, through which oxygen availability or redox-dependent protein modifications control thermomorphogenic signalling, largely downstream of or independent of PIF4. Logical argument suggests that significant mechanisms and crosstalk between oxygen and redox signalling and thermosensing remain to be revealed.