Target genes and regulatory domains of the GAMYB transcriptional activator in cereal aleurone

Plant J. 1999 Jan;17(1):1-9. doi: 10.1046/j.1365-313x.1999.00346.x.


GAMYB is an MYB transcription factor which is expressed in cereal aleurone cells in response to gibberellin (GA). HvGAMYB binds to the TAACAAA box of a high-pl alpha-amylase gene promoter and transcriptionally activates its expression. In this study, we examined the role of HvGAMYB in activating expression of other GA-regulated genes encoding hydrolytic enzymes. In transient expression experiments, HvGAMYB transactivated expression of reporter genes fused to a low-pl alpha-amylase gene promoter, an EII (1-3, 1-4)-beta-glucanase gene promoter and a cathepsin B-like protease promoter. HvGAMYB DNA binding specificity was determined using a PCR-based random site selection using HvGAMYB fusion protein isolated from E. coli. The deduced consensus closely resembled gibberellin response elements in alpha-amylase promoters. Functional analysis of HvGAMYB by transient expression of C terminal HvGAMYB deletions in barley aleurone cells identified two transcriptional activation domains (TADs) which function in transcriptional regulation of both high- and low-pl alpha-amylase promoters. The same TADs were identified using a heterologous yeast expression system. Together, these results indicate that HvGAMYB has two TADs. These domains are C-terminal to its DNA-binding domain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Binding Sites
  • Cloning, Molecular
  • Edible Grain / genetics*
  • Edible Grain / metabolism*
  • Gene Expression Regulation, Plant*
  • Genes, Reporter
  • Gibberellins / pharmacology
  • Hordeum / genetics*
  • Hordeum / metabolism
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Plant Proteins / chemistry
  • Plant Proteins / metabolism
  • Promoter Regions, Genetic / drug effects
  • Recombinant Fusion Proteins / biosynthesis
  • Saccharomyces cerevisiae
  • Sequence Deletion
  • Substrate Specificity
  • Transcription Factors / chemistry
  • Transcription Factors / metabolism*
  • Transcriptional Activation
  • alpha-Amylases / genetics*


  • Gibberellins
  • Plant Proteins
  • Recombinant Fusion Proteins
  • Transcription Factors
  • alpha-Amylases