FLOWERING LOCUS T mediates photo-thermal timing of inflorescence meristem arrest in Arabidopsis thaliana.

Plants integrate environmental information into their developmental program throughout their lifetime. Light and temperature are particularly critical cues for plants to correctly time developmental transitions. Here, we investigated the role of photo-thermal cues in the regulation of the end-of-flowering developmental transition in the model plant Arabidopsis (Arabidopsis thaliana). We found that increased day length and higher temperature during flowering promote earlier inflorescence arrest by accelerating the rate at which the inflorescence meristem initiates floral primordia. Specifically, we show that plants arrest at a photo-thermal threshold and demonstrate that this photothermally-mediated arrest is mediated by the floral integrator FLOWERING LOCUS T (FT), a known activator of flowering. FT expression increased over the duration of flowering, peaking during inflorescence meristem arrest, and we show that this is necessary and sufficient for photothermally-induced arrest. Our data demonstrates the role of light and temperature, through FT, as key regulators of end-of-flowering. Overall, our results have important implications for understanding and modulating flowering duration of crop species in changing light and temperature conditions in a warming global climate.