The Arabidopsis GAI gene defines a signaling pathway that negatively regulates gibberellin responses

Genes Dev. 1997 Dec 1;11(23):3194-205. doi: 10.1101/gad.11.23.3194.


The Arabidopsis gai mutant allele confers a reduction in gibberellin (GA) responsiveness. Here we report the molecular cloning of GAI and a closely related gene GRS. The predicted GAI (wild-type) and gai (mutant) proteins differ only by the deletion of a 17-amino-acid segment from within the amino-terminal region. GAI and GRS contain nuclear localization signals, a region of homology to a putative transcription factor, and motifs characteristic of transcriptional coactivators. Genetic analysis indicates that GAI is a repressor of GA responses, that GA can release this repression, and that gai is a mutant repressor that is relatively resistant to the effects of GA. Mutations at SPY and GAR2 suppress the gai phenotype, indicating the involvement of GAI, SPY, and GAR2 in a signaling pathway that regulates GA responses negatively. The existence of this pathway suggests that GA modulates plant growth through derepression rather than through simple stimulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Amino Acid Sequence
  • Arabidopsis / drug effects
  • Arabidopsis / genetics*
  • Arabidopsis / growth & development
  • Arabidopsis Proteins*
  • Base Sequence
  • Cloning, Molecular
  • Consensus Sequence
  • DNA, Plant
  • Genes, Plant*
  • Gibberellins / antagonists & inhibitors*
  • Gibberellins / pharmacology
  • Mixed Function Oxygenases / genetics
  • Molecular Sequence Data
  • Mutagenesis, Insertional
  • Nuclear Localization Signals / genetics
  • Open Reading Frames
  • Plant Growth Regulators / pharmacology
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • RNA, Plant / metabolism
  • Sequence Homology, Amino Acid
  • Signal Transduction*
  • Suppression, Genetic
  • Triazoles / pharmacology


  • Arabidopsis Proteins
  • DNA, Plant
  • GAI protein, Arabidopsis
  • GRS protein, Arabidopsis
  • Gibberellins
  • Nuclear Localization Signals
  • Plant Growth Regulators
  • Plant Proteins
  • RNA, Plant
  • Triazoles
  • paclobutrazol
  • Mixed Function Oxygenases
  • gibberellin, 2-oxoglutarate-oxygen oxidoreductase (20-hydroxylating, oxidizing)

Associated data

  • GENBANK/Y15193
  • GENBANK/Y15194