dwarf and delayed-flowering 1, a novel Arabidopsis mutant deficient in gibberellin biosynthesis because of overexpression of a putative AP2 transcription factor

Plant J. 2004 Mar;37(5):720-9. doi: 10.1111/j.1365-313x.2003.01998.x.


A novel gibberellin (GA)-deficient mutant designated dwarf and delayed-flowering 1 (ddf1) was isolated from a library of activation-tagged Arabidopsis. This mutant showed dwarfism and late-flowering, but the phenotype was rescued by exogenous GA3 like known mutants defective in GA biosynthesis. The contents of bioactive GA4 and GA1 were in fact decreased in ddf1 at least partially through the repression of biosynthetic steps catalyzed by GA 20-oxidase (GA20ox). Genetic and molecular analyses revealed that the ddf1 phenotypes are caused by increased or ectopic expression of a putative AP2 transcription factor. Overexpression of DDF2, encoding another putative AP2 transcription factor closely related to DDF1, also conferred the ddf1-like phenotype. Among genes encoding (putative) AP2 transcription factors in Arabidopsis, DDFs are phylogenetically close to dehydration-responsive element binding protein (DREB1)/C-repeat binding factor (CBF) genes, which are known to be involved in stress responses. The ddf1 mutation upregulates a stress-related gene RD29A. DDF1 mRNA is strongly induced by high-salinity stress within 1 h. Moreover, transgenic plants overexpressing DDF1 showed increased tolerance to high-salinity stress. These results suggest that DDF1 is involved in the regulation of GA biosynthesis and stress tolerance. The possible relation between the contents of endogenous GAs and acquisition of stress protection is discussed.

MeSH terms

  • Adaptation, Physiological / genetics
  • Adaptation, Physiological / physiology
  • Amino Acid Sequence
  • Arabidopsis / genetics
  • Arabidopsis / metabolism
  • Arabidopsis / ultrastructure
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / metabolism*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Gene Expression Regulation, Developmental / drug effects
  • Gene Expression Regulation, Plant / drug effects
  • Gibberellins / biosynthesis*
  • Gibberellins / pharmacology
  • Microscopy, Electron, Scanning
  • Mixed Function Oxygenases / genetics
  • Mixed Function Oxygenases / metabolism
  • Molecular Sequence Data
  • Mutation
  • Osmotic Pressure / drug effects
  • Phenotype
  • Phylogeny
  • Plants, Genetically Modified
  • Sequence Homology, Amino Acid
  • Sodium Chloride / pharmacology
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism


  • Arabidopsis Proteins
  • CBF1 protein, Arabidopsis
  • DDF1 protein, Arabidopsis
  • DDF2 protein, Arabidopsis
  • DNA-Binding Proteins
  • DREB1A protein, Arabidopsis
  • Gibberellins
  • Trans-Activators
  • Transcription Factors
  • Sodium Chloride
  • gibberellic acid
  • Mixed Function Oxygenases
  • AtGA2ox7 protein, Arabidopsis
  • AtGA2ox8 protein, Arabidopsis
  • gibberellin 2-dioxygenase