Warm temperature-triggered developmental reprogramming requires VIL1-mediated genome-wide H3K27me3 accumulation in Arabidopsis.

Changes in ambient temperature immensely affect developmental programs in many species. Plants adapt to high ambient growth temperature in part by vegetative and reproductive developmental reprograming, known as thermo-morphogenesis. Thermo-morphogenesis is accompanied by massive changes in transcriptome upon temperature change. Here, we show that changes in transcriptome by warm ambient temperature requires VERNALIZATION INSENSITIVE 3-LIKE 1/VERNALIZATION 5 (VIL1/VRN5), a facultative component of Polycomb Repressive Complex 2 (PRC2), in Arabidopsis. Warm growth temperature elicits genome-wide accumulation of H3K27me3 and VIL1 is necessary for the warm temperature-mediated accumulation of H3K27me3. Consistent with its role as a mediator of thermo-morphogenesis, loss of function of VIL1 results in hypo-response to warm ambient temperature. Our results show that VIL1 is a major chromatin regulator in high ambient temperature responses.