Ambient temperature influences plant growth and development and minor changes can substantially impact crop yields. The underlying mechanisms for temperature perception and response are just beginning to emerge. Chromatin remodeling via the eviction of the histone variant H2A.Z in nucleosomes that alters gene expression is a critical component of thermal response in plants. However, whether chromatin-remodeling processes such as histone modifications play a global role in thermal response

more »

... s unknown. Using a combination of genetic analysis, chemical inhibition studies and RNA-seq analysis coupled with meta-analysis, here we identify POWERDRESS (PWR), a SANT-domain containing protein that is known to interact with HISTONE DEACETYLASE 9 (HDA9), as a novel key factor required for thermomorphogenesis in Arabidopsis thaliana. We identify that mutations in PWR impede thermomorphogenesis exemplified by severely attenuated temperature-induced hypocotyl/petiole elongation and early flowering. We show that inhibitors of histone deacetylases diminish temperature-induced hypocotyl elongation, which demonstrates for the first time a requirement for histone deacetylation in thermomorphogenesis. Genes that are misregulated in pwr mutants showed enrichment for GO terms associated with response. Our expression studies coupled with meta-analysis revealed a significant overlap between genes misregulated in pwr mutants and genes that are enriched for H2A.Z in their gene bodies. Meta-analyses reveal that genes misregulated in pwr mutants in diverse conditions also overlap with genes that are differentially expressed in the mutants of the components of the SWR1 complex that mediates H2A.Z nucleosome dynamics. Our findings thus uncover a role for PWR in facilitating thermal response and suggest a potential link between histone deacetylation and H2A.Z nucleosome dynamics in regulation of gene expression in plants.