title: Heat shock transcriptional factors in Malus domestica: identification, classification and expression analysis.
abstract: BACKGROUND
  Heat shock transcriptional factors (Hsfs) play a crucial role in plant responses to biotic and abiotic stress conditions and in plant growth and development. Apple (Malus domestica Borkh) is an economically important fruit tree whose genome has been fully sequenced. So far, no detailed characterization of the Hsf gene family is available for this crop plant.
  
  
  RESULTS
  A genome-wide analysis was carried out in Malus domestica to identify heat shock transcriptional factor (Hsf) genes, named MdHsfs. Twenty five MdHsfs were identified and classified in three main groups (class A, B and C) according to the structural characteristics and to the phylogenetic comparison with Arabidopsis thaliana and Populus trichocarpa. Chromosomal duplications were analyzed and segmental duplications were shown to have occurred more frequently in the expansion of Hsf genes in the apple genome. Furthermore, MdHsfs transcripts were detected in several apple organs, and expression changes were observed by quantitative real-time PCR (qRT-PCR) analysis in developing flowers and fruits as well as in leaves, harvested from trees grown in the field and exposed to the naturally increased temperatures.
  
  
  CONCLUSIONS
  The apple genome comprises 25 full length Hsf genes. The data obtained from this investigation contribute to a better understanding of the complexity of the Hsf gene family in apple, and provide the basis for further studies to dissect Hsf function during development as well as in response to environmental stimuli.
authors.affiliation: Research Centre for Agriculture and Forestry Laimburg, Laimburg 6, Auer/Ora, BZ, 39040, Italy. mgiorno@science.ru.nl
authors.forename: Filomena
authors.initials: F
authors.lastname: Giorno
authors.forename: Gea
authors.initials: G
authors.lastname: Guerriero
authors.forename: Sanja
authors.initials: S
authors.lastname: Baric
authors.forename: Celestina
authors.initials: C
authors.lastname: Mariani
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D058674:Chromosome Duplication; D004268:DNA-Binding Proteins / Q000235:genetics*; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D018745:Genome, Plant / Q000235:genetics*; D055106:Genome-Wide Association Study; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics; D027845:Malus / Q000235:genetics* / Q000378:metabolism*; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D032107:Populus / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D004268:DNA-Binding Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D010940:Plant Proteins; D014157:Transcription Factors