title: Genome-wide analysis of the Hsf family in soybean and functional identification of GmHsf-34 involvement in drought and heat stresses.
abstract: BACKGROUND
  High temperature affects organism growth and metabolic activity. Heat shock transcription factors (Hsfs) are key regulators in heat shock response in eukaryotes and prokaryotes. Under high temperature conditions, Hsfs activate heat shock proteins (Hsps) by combining with heat stress elements (HSEs) in their promoters, leading to defense of heat stress. Since the first plant Hsf gene was identified in tomato, several plant Hsf family genes have been thoroughly characterized. Although soybean (Glycine max), an important oilseed crops, genome sequences have been available, the Hsf family genes in soybean have not been characterized accurately.
  
  
  RESULTS
  We analyzed the Hsf genetic structures and protein function domains using the GSDS, Pfam, SMART, PredictNLS, and NetNES online tools. The genome scanning of dicots (soybean and Arabidopsis) and monocots (rice and maize) revealed that the whole-genome replication occurred twice in soybean evolution. The plant Hsfs were classified into 3 classes and 16 subclasses according to protein structure domains. The A8 and B3 subclasses existed only in dicots and the A9 and C2 occurred only in monocots. Thirty eight soybean Hsfs were systematically identified and grouped into 3 classes and 12 subclasses, and located on 15 soybean chromosomes. The promoter regions of the soybean Hsfs contained cis-elements that likely participate in drought, low temperature, and ABA stress responses. There were large differences among Hsfs based on transcriptional levels under the stress conditions. The transcriptional levels of the A1 and A2 subclass genes were extraordinarily high. In addition, differences in the expression levels occurred for each gene in the different organs and at the different developmental stages. Several genes were chosen to determine their subcellular localizations and functions. The subcellular localization results revealed that GmHsf-04, GmHsf-33, and GmHsf-34 were located in the nucleus. Overexpression of the GmHsf-34 gene improved the tolerances to drought and heat stresses in Arabidopsis plants.
  
  
  CONCLUSIONS
  This present investigation of the quantity, structural features, expression characteristics, subcellular localizations, and functional roles provides a scientific basis for further research on soybean Hsf functions.
authors.forename: Pan-Song
authors.initials: PS
authors.lastname: Li
authors.forename: Tai-Fei
authors.initials: TF
authors.lastname: Yu
authors.forename: Guan-Hua
authors.initials: GH
authors.lastname: He
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.forename: Yong-Bin
authors.initials: YB
authors.lastname: Zhou
authors.affiliation: College of Agronomy, Northwest A & F University, Yangling 712100, China. chaishoucheng@126.com.
authors.forename: Shou-Cheng
authors.initials: SC
authors.lastname: Chai
authors.forename: Zhao-Shi
authors.initials: ZS
authors.lastname: Xu
authors.forename: You-Zhi
authors.initials: YZ
authors.lastname: Ma
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000378:metabolism; D032461:Chromosomes, Plant / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D055864:Droughts; D005091:Exons / Q000235:genetics; D020440:Gene Duplication; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D055106:Genome-Wide Association Study; D000076249:Heat Shock Transcription Factors; D006358:Hot Temperature; D007438:Introns / Q000235:genetics; D007526:Isoelectric Point; D008969:Molecular Sequence Data; D008970:Molecular Weight; D005810:Multigene Family; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D016415:Sequence Alignment; D013025:Glycine max / Q000235:genetics* / Q000502:physiology; D013312:Stress, Physiological / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D000076249:Heat Shock Transcription Factors; D010940:Plant Proteins; D014157:Transcription Factors