A chromatin switch attenuates abiotic stress responses during the floral transition

While stress conditions are known to impact plant development, how developmental transitions influence responses to adverse conditions has not been addressed, and the molecular mechanisms underlying the integration of plant development with stress responses remain obscure. Here, we reveal a novel molecular mechanism of stress response attenuation during the onset of flowering in the model plant species Arabidopsis. This work shows that Arabidopsis proteins that form part of a histone acetyltransferase complex and that bind methylated forms of histone H3, function as a chromatin switch on the floral integrator gene SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1) to coordinate flowering initiation with plant responsiveness to hostile environments. These chromatin proteins are required to activate SOC1 expression during flowering induction by promoting histone H4 acetylation. In turn, SOC1 represses a broad array of genes that mediate abiotic stress responses such as cold or drought tolerance. The results obtained indicate that during the transition from vegetative to reproductive growth, this epigenetic switch that acts on SOC1 constitutes a central hub in a mechanism that tunes down stress responses to enhance reproductive success and plant fitness at the expense of costly efforts for adaptation to challenging environments.