The heat stress transcription factor HsfA2 serves as a regulatory amplifier of a subset of genes in the heat stress response in Arabidopsis

Plant Mol Biol. 2006 Mar;60(5):759-72. doi: 10.1007/s11103-005-5750-x.


Within the Arabidopsis family of 21 heat stress transcription factors (Hsfs) HsfA2 is the strongest expressed member under heat stress (hs) conditions. Irrespective of the tissue, HsfA2 accumulates under heat stress similarly to other heat stress proteins (Hsps). A SALK T-DNA insertion line with a complete HsfA2-knockout was analyzed with respect to the changes in the transcriptome under heat stress conditions. Ascorbate peroxidase 2 (APX2) was identified as the most affected transcript in addition to several sHsps, individual members of the Hsp70 and Hsp100 family, as well as many transcripts of genes with yet unknown functions. For functional validation, the transcription activation potential of HsfA2 on GUS reporter constructs containing 1 kb upstream promoter sequences of selected target genes were analyzed using transient reporter assays in mesophyll protoplasts. By deletion analysis the promoter region of the strongest affected target gene APX2 was functionally mapped in detail to verify potential HsfA2 binding sites. By electrophoretic mobility shift assays we identified TATA-Box proximal clusters of heat stress elements (HSE) in the promoters of selected target genes as potential HsfA2 binding sites. The results presented here demonstrate that the expression of HsfA2 in Arabidopsis is strictly heat stress-dependent and this transcription factor represents a regulator of a subset of stress response genes in Arabidopsis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Binding Sites / genetics
  • Blotting, Western
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Electrophoretic Mobility Shift Assay
  • Gene Expression Regulation, Plant*
  • Glucuronidase / genetics
  • Glucuronidase / metabolism
  • Heat Shock Transcription Factors
  • Heat-Shock Proteins / genetics
  • Heat-Shock Proteins / metabolism
  • Hot Temperature*
  • Mutation
  • Peroxidases / genetics
  • Peroxidases / metabolism
  • Plant Proteins / genetics
  • Plant Proteins / metabolism
  • Promoter Regions, Genetic / genetics
  • Protoplasts / metabolism
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tobacco / genetics
  • Tobacco / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transfection


  • Arabidopsis Proteins
  • DNA-Binding Proteins
  • HSFA2 protein, Arabidopsis
  • Heat Shock Transcription Factors
  • Heat-Shock Proteins
  • Plant Proteins
  • Recombinant Fusion Proteins
  • Transcription Factors
  • Peroxidases
  • Glucuronidase