title: Hsf and Hsp gene families in Populus: genome-wide identification, organization and correlated expression during development and in stress responses.
abstract: BACKGROUND
  Heat shock proteins (Hsps) are molecular chaperones that are involved in many normal cellular processes and stress responses, and heat shock factors (Hsfs) are the transcriptional activators of Hsps. Hsfs and Hsps are widely coordinated in various biological processes. Although the roles of Hsfs and Hsps in stress responses have been well characterized in Arabidopsis, their roles in perennial woody species undergoing various environmental stresses remain unclear.
  
  
  RESULTS
  Here, a comprehensive identification and analysis of Hsf and Hsp families in poplars is presented. In Populus trichocarpa, we identified 42 paralogous pairs, 66.7% resulting from a whole genome duplication. The gene structure and motif composition are relatively conserved in each subfamily. Microarray and quantitative real-time RT-PCR analyses showed that most of the Populus Hsf and Hsp genes are differentially expressed upon exposure to various stresses. A coexpression network between Populus Hsf and Hsp genes was generated based on their expression. Coordinated relationships were validated by transient overexpression and subsequent qPCR analyses.
  
  
  CONCLUSIONS
  The comprehensive analysis indicates that different sets of PtHsps are downstream of particular PtHsfs and provides a basis for functional studies aimed at revealing the roles of these families in poplar development and stress responses.
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, China. zhang007jin@163.com.|Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China. zhang007jin@163.com.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, China. 163liubobin0377@163.com.|College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China. 163liubobin0377@163.com.
authors.forename: Bobin
authors.initials: B
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, China. Bobo413510@163.com.
authors.forename: Jianbo
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, China. zhanglisdau86@126.com.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, Shandong, 271018, China. 947728286@qq.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Biology, McGill University, 1205 Dr Penfield Avenue, Montreal, Quebec, H3A 1B1, Canada. hugo.zheng@mcgill.ca.
authors.forename: Huanquan
authors.initials: H
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, China. lumz@caf.ac.cn.|Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China. lumz@caf.ac.cn.
authors.forename: Mengzhu
authors.initials: M
authors.lastname: Lu
authors.affiliation: State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, China. chenjun@caf.ac.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
mesh_terms: D020816:Amino Acid Motifs; D002874:Chromosome Mapping; D017124:Conserved Sequence; D020440:Gene Duplication; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks; D017343:Genes, Plant; D018745:Genome, Plant; D005810:Multigene Family; D009928:Organ Specificity / Q000235:genetics; D010802:Phylogeny; D032107:Populus / Q000235:genetics*; D013312:Stress, Physiological; D014158:Transcription, Genetic