POWERDRESS-mediated histone deacetylation is essential for thermomorphogenesis inArabidopsis thaliana
Authors: Tasset Celine , Singh Yadav Avilash , Sureshkumar Sridevi , Singh Rupali , van der Woude Lennard , Nekrasov Maxim , Tremethick David , van Zanten Martijn , Balasubramanian Sureshkumar 
Published: September 2017

AbstractAmbient 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 remains 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 inArabidopsis thaliana. We identify that mutations inPWRimpede 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 inpwrmutants showed enrichment for GO terms associated with “response”. Our expression studies coupled with meta-analysis revealed a significant overlap between genes misregulated inpwrmutants and genes that are enriched for H2A.Z in their gene bodies. Meta-analyses reveal that genes misregulated inpwrmutants 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.Author summaryPlant growth and development is influenced by a variety of external environmental cues. Ambient temperature affects almost all stages of plant development but the underlying molecular mechanisms remain largely unknown. In this paper, the authors show that histone deacetylation, one of the major chromatin remodeling processes, is essential for eliciting growth temperature-induced responses in plants. The authors identify POWERDRESS, a protein known to interact with HISTONE DEACETYLASE 9, as a novel key player essential for eliciting high temperature induced responses in Arabidopsis. Another chromatin remodeling mechanism that is known to play a role in thermal response is the eviction of histone variant H2A.Z from nucleosomes. Through transcriptome studies the authors demonstrate an overlap between gene regulations conferred through PWR-mediated histone H3 deacetylation and that conferred via histone H2A.Z eviction/incorporation dynamics. This study identifies a key novel gene that is essential for plants to elicit high temperature responses and reveals close links between two seemingly distinct chromatin-remodeling processes in regulating gene expression in plants.