DREB1A/CBF3 Is Repressed by Transgene-Induced DNA Methylation in the Arabidopsis ice1 -1 Mutant

Plant Cell. 2020 Apr;32(4):1035-1048. doi: 10.1105/tpc.19.00532. Epub 2020 Feb 7.


DREB1/CBFs are key transcription factors involved in plant cold stress adaptation. The expression of DREB1/CBFs triggers a cold-responsive transcriptional cascade, after which many stress tolerance genes are expressed. Thus, elucidating the mechanisms of cold stress-inducible DREB1/CBF expression is important to understand the molecular mechanisms of plant cold stress responses and tolerance. We analyzed the roles of a transcription factor, INDUCER OF CBF EXPRESSION1 (ICE1), that is well known as an important transcriptional activator in the cold-inducible expression of DREB1A/CBF3 in Arabidopsis (Arabidopsis thaliana). ice1-1 is a widely accepted mutant allele known to abolish cold-inducible DREB1A expression, and this evidence has strongly supported ICE1-DREB1A regulation for many years. However, in ice1-1 outcross descendants, we unexpectedly discovered that ice1-1 DREB1A repression was genetically independent of the ice1-1 allele ICE1(R236H). Moreover, neither ICE1 overexpression nor double loss-of-function mutation of ICE1 and its homolog SCRM2 altered DREB1A expression. Instead, a transgene locus harboring a reporter gene in the ice1-1 genome was responsible for altering DREB1A expression. The DREB1A promoter was hypermethylated due to the transgene. We showed that DREB1A repression in ice1-1 results from transgene-induced silencing and not genetic regulation by ICE1. The ICE1(R236H) mutation has also been reported as scrm-D, which confers constitutive stomatal differentiation. The scrm-D phenotype and the expression of a stomatal differentiation marker gene were confirmed to be linked to the ICE1(R236H) mutation. We propose that the current ICE1-DREB1 regulatory model should be revalidated without the previous assumptions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Arabidopsis / genetics*
  • Arabidopsis Proteins / metabolism*
  • Cold-Shock Response
  • DNA Methylation / genetics*
  • DNA, Bacterial / genetics
  • Mutagenesis, Insertional / genetics
  • Mutation / genetics*
  • Plants, Genetically Modified
  • Promoter Regions, Genetic
  • Repressor Proteins / metabolism*
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism*
  • Transgenes*


  • Arabidopsis Proteins
  • DNA, Bacterial
  • DREB1A protein, Arabidopsis
  • ICE1 protein, Arabidopsis
  • Repressor Proteins
  • T-DNA
  • Transcription Factors