title: Genome-wide identification and comparative analysis of the heat shock transcription factor family in Chinese white pear (Pyrus bretschneideri) and five other Rosaceae species.
abstract: BACKGROUND
  Heat shock transcription factors (Hsfs), which act as important transcriptional regulatory proteins in eukaryotes, play a central role in controlling the expression of heat-responsive genes. At present, the genomes of Chinese white pear ('Dangshansuli') and five other Rosaceae fruit crops have been fully sequenced. However, information about the Hsfs gene family in these Rosaceae species is limited, and the evolutionary history of the Hsfs gene family also remains unresolved.
  
  
  RESULTS
  In this study, 137 Hsf genes were identified from six Rosaceae species (Pyrus bretschneideri, Malus × domestica, Prunus persica, Fragaria vesca, Prunus mume, and Pyrus communis), 29 of which came from Chinese white pear, designated as PbHsf. Based on the structural characteristics and phylogenetic analysis of these sequences, the Hsf family genes could be classified into three main groups (classes A, B, and C). Segmental and dispersed duplications were the primary forces underlying Hsf gene family expansion in the Rosaceae. Most of the PbHsf duplicated gene pairs were dated back to the recent whole-genome duplication (WGD, 30-45 million years ago (MYA)). Purifying selection also played a critical role in the evolution of Hsf genes. Transcriptome data demonstrated that the expression levels of the PbHsf genes were widely different. Six PbHsf genes were upregulated in fruit under naturally increased temperature.
  
  
  CONCLUSIONS
  A comprehensive analysis of Hsf genes was performed in six Rosaceae species, and 137 full length Hsf genes were identified. The results presented here will undoubtedly be useful for better understanding the complexity of the Hsf gene family and will facilitate functional characterization in future studies.
authors.affiliation: College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China. 2014204010@njau.edu.cn.
authors.forename: Xin
authors.initials: X
authors.lastname: Qiao
authors.affiliation: College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China. mli@njau.edu.cn.
authors.forename: Meng
authors.initials: M
authors.lastname: Li
authors.affiliation: College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China. lileiting@gmail.com.
authors.forename: Leiting
authors.initials: L
authors.lastname: Li
authors.affiliation: College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China. yinhao85@gmail.com.
authors.forename: Hao
authors.initials: H
authors.lastname: Yin
authors.affiliation: College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China. juyouwu@njau.edu.cn.
authors.forename: Juyou
authors.initials: J
authors.lastname: Wu
authors.affiliation: College of Horticulture, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China. slzhang@njau.edu.cn.
authors.forename: Shaoling
authors.initials: S
authors.lastname: Zhang
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D005638:Fruit / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018745:Genome, Plant; D000076249:Heat Shock Transcription Factors; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D031989:Pyrus / Q000235:genetics*; D027824:Rosaceae / Q000235:genetics*; D056916:Segmental Duplications, Genomic / Q000235:genetics; D013045:Species Specificity; D026801:Synteny / Q000235:genetics; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D000076249:Heat Shock Transcription Factors; D010940:Plant Proteins; D014157:Transcription Factors