A recently evolved isoform of the transcription factor BES1 promotes brassinosteroid signaling and development in Arabidopsis thaliana

Plant Cell. 2015 Feb;27(2):361-74. doi: 10.1105/tpc.114.133678. Epub 2015 Feb 3.


Brassinosteroids (BRs) are essential steroid hormones that regulate plant growth and development. The transcription factor BRI1-EMS-SUPPRESSOR1 (BES1) regulates the expression of thousands of target genes in response to BRs. Here, we report an Arabidopsis thaliana-specific long isoform of BES1, BES1-L, which has stronger activity in promoting BR signaling than the canonical and widely used short BES1-S. The BES1-L isoform contains an additional N-terminal bipartite nuclear localization signal, which strongly promotes its nuclear localization. BES1-L also promotes the nuclear localization of BES1-S and BRASSINAZOLE-RESISTANT1 via dimerization. The transcription of BES1-L and BES1-S is differentially regulated by BRs due to the presence of G-box element in the BES1-S promoter. Moreover, BES1-L uniquely exists in the majority of A. thaliana ecotypes, but not in other species, even its Brassicaceae relatives, including Arabidopsis lyrata. The phenotypes of the BES1-L overexpression lines and plants with truncated BES1-L indicate that BES1-L is a more important isoform of BES1 in Arabidopsis and may have contributed to the evolution and expansion of A. thaliana.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / genetics
  • Arabidopsis / growth & development*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Base Sequence
  • Brassinosteroids / metabolism*
  • Cell Nucleus / metabolism
  • DNA-Binding Proteins
  • Darkness
  • Evolution, Molecular*
  • Gene Expression Regulation, Plant
  • Green Fluorescent Proteins / metabolism
  • Hypocotyl / growth & development
  • Hypocotyl / metabolism
  • Molecular Sequence Data
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Phenotype
  • Plant Development*
  • Plants, Genetically Modified
  • Protein Isoforms / chemistry
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Protein Transport
  • Signal Transduction* / genetics
  • Subcellular Fractions / metabolism
  • Tobacco / genetics
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transcription, Genetic


  • Arabidopsis Proteins
  • BES1 protein, Arabidopsis
  • BZR1 protein, Arabidopsis
  • Brassinosteroids
  • DNA-Binding Proteins
  • Nuclear Proteins
  • Protein Isoforms
  • Transcription Factors
  • Green Fluorescent Proteins