Four Arabidopsis AREB/ABF transcription factors function predominantly in gene expression downstream of SnRK2 kinases in abscisic acid signalling in response to osmotic stress

Plant Cell Environ. 2015 Jan;38(1):35-49. doi: 10.1111/pce.12351. Epub 2014 May 22.


Under osmotic stress conditions such as drought and high salinity, the plant hormone abscisic acid (ABA) plays important roles in stress-responsive gene expression mainly through three bZIP transcription factors, AREB1/ABF2, AREB2/ABF4 and ABF3, which are activated by SNF1-related kinase 2s (SnRK2s) such as SRK2D/SnRK2.2, SRK2E/SnRK2.6 and SRK2I/SnRK2.3 (SRK2D/E/I). However, since the three AREB/ABFs are crucial, but not exclusive, for the SnRK2-mediated gene expression, transcriptional pathways governed by SRK2D/E/I are not fully understood. Here, we show that a bZIP transcription factor, ABF1, is a functional homolog of AREB1, AREB2 and ABF3 in ABA-dependent gene expression in Arabidopsis. Despite lower expression levels of ABF1 than those of the three AREB/ABFs, the areb1 areb2 abf3 abf1 mutant plants displayed increased sensitivity to drought and decreased sensitivity to ABA in primary root growth compared with the areb1 areb2 abf3 mutant. Genome-wide transcriptome analyses revealed that expression of downstream genes of SRK2D/E/I, which include many genes functioning in osmotic stress responses and tolerance such as transcription factors and LEA proteins, was mostly impaired in the quadruple mutant. Thus, these results indicate that the four AREB/ABFs are the predominant transcription factors downstream of SRK2D/E/I in ABA signalling in response to osmotic stress during vegetative growth.

Keywords: ABF1; transcriptional regulation; transcriptome analysis..

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abscisic Acid / metabolism*
  • Arabidopsis / cytology
  • Arabidopsis / genetics
  • Arabidopsis / physiology*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Basic-Leucine Zipper Transcription Factors / genetics
  • Basic-Leucine Zipper Transcription Factors / metabolism*
  • Droughts
  • Gene Expression
  • Gene Expression Profiling
  • Gene Expression Regulation, Plant*
  • Genes, Reporter
  • Mutation
  • Oligonucleotide Array Sequence Analysis
  • Osmotic Pressure
  • Plant Growth Regulators / metabolism*
  • Plant Roots / cytology
  • Plant Roots / genetics
  • Plant Roots / physiology
  • Plants, Genetically Modified
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Seedlings / cytology
  • Seedlings / genetics
  • Seedlings / physiology
  • Signal Transduction*
  • Stress, Physiological


  • ABF1 protein, Arabidopsis
  • Arabidopsis Proteins
  • Basic-Leucine Zipper Transcription Factors
  • Plant Growth Regulators
  • SnRK2 protein, Arabidopsis
  • Abscisic Acid
  • Protein-Serine-Threonine Kinases