title: Genome-wide analysis, expression profile of heat shock factor gene family (CaHsfs) and characterisation of CaHsfA2 in pepper (Capsicum annuum L.).
abstract: BACKGROUND
  Heat shock factors (Hsfs) play crucial roles in plant developmental and defence processes. The production and quality of pepper (Capsicum annuum L.), an economically important vegetable crop, are severely reduced by adverse environmental stress conditions, such as heat, salt and osmotic stress. Although the pepper genome has been fully sequenced, the characterization of the Hsf gene family under abiotic stress conditions remains incomplete.
  
  
  RESULTS
  A total of 25 CaHsf members were identified in the pepper genome by bioinformatics analysis and PCR assays. They were grouped into three classes, CaHsfA, B and C, based on highly conserved Hsf domains, were distributed over 11 of 12 chromosomes, with none found on chromosome 11, and all of them, except CaHsfA5, formed a protein-protein interaction network. According to the RNA-seq data of pepper cultivar CM334, most CaHsf members were expressed in at least one tissue among root, stem, leaf, pericarp and placenta. Quantitative real-time PCR assays showed that all of the CaHsfs responded to heat stress (40 °C for 2 h), except CaHsfC1 in thermotolerant line R9 leaves, and that the expression patterns were different from those in thermosensitive line B6. Many CaHsfs were also regulated by salt and osmotic stresses, as well as exogenous Ca(2+), putrescine, abscisic acid and methyl jasmonate. Additionally, CaHsfA2 was located in the nucleus and had transcriptional activity, consistent with the typical features of Hsfs. Time-course expression profiling of CaHsfA2 in response to heat stress revealed differences in its expression level and pattern between the pepper thermosensitive line B6 and thermotolerant line R9.
  
  
  CONCLUSIONS
  Twenty-five Hsf genes were identified in the pepper genome and most of them responded to heat, salt, osmotic stress, and exogenous substances, which provided potential clues for further analyses of CaHsfs functions in various kinds of abiotic stresses and of corresponding signal transduction pathways in pepper.
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, P. R., China. guomeng19881025@126.com.
authors.forename: Meng
authors.initials: M
authors.lastname: Guo
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, P. R., China. lujinpingok@163.com.
authors.forename: Jin-Ping
authors.initials: JP
authors.lastname: Lu
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, P. R., China. 18829785690@163.com.
authors.forename: Yu-Fei
authors.initials: YF
authors.lastname: Zhai
authors.affiliation: Institute of Vegetables, Hangzhou Academy of Agricultural Sciences, Hangzhou, Zhejiang, 310024, P. R., China. kuni@21cn.com.
authors.forename: Wei-Guo
authors.initials: WG
authors.lastname: Chai
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, P. R., China. zhgong@nwsuaf.edu.cn.
authors.forename: Zhen-Hui
authors.initials: ZH
authors.lastname: Gong
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, Shaanxi, 712100, P. R., China. xnjacklu@nwsuaf.edu.cn.
authors.forename: Ming-Hui
authors.initials: MH
authors.lastname: Lu
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002212:Capsicum / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D032461:Chromosomes, Plant / Q000235:genetics; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D020440:Gene Duplication / Q000187:drug effects; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D018745:Genome, Plant; D000076249:Heat Shock Transcription Factors; D008969:Molecular Sequence Data; D005810:Multigene Family; D009928:Organ Specificity / Q000187:drug effects / Q000235:genetics; D009997:Osmotic Pressure / Q000187:drug effects; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D060066:Protein Interaction Maps / Q000235:genetics; D017434:Protein Structure, Tertiary; D020539:Sequence Analysis, Protein; D012965:Sodium Chloride / Q000494:pharmacology; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D000076249:Heat Shock Transcription Factors; D010937:Plant Growth Regulators; D010940:Plant Proteins; D014157:Transcription Factors; D012965:Sodium Chloride