CHOTTO1, a putative double APETALA2 repeat transcription factor, is involved in abscisic acid-mediated repression of gibberellin biosynthesis during seed germination in Arabidopsis

Plant Physiol. 2009 Oct;151(2):641-54. doi: 10.1104/pp.109.142018. Epub 2009 Jul 31.


The phytohormones abscisic acid (ABA) and gibberellins (GAs) are the primary signals that regulate seed dormancy and germination. In this study, we investigated the role of a double APETALA2 repeat transcription factor, CHOTTO1 (CHO1), in seed dormancy, germination, and phytohormone metabolism of Arabidopsis (Arabidopsis thaliana). Wild-type seeds were dormant when freshly harvested seeds were sown, and these seeds were released from dormancy after a particular period of dry storage (after-ripening). The cho1 mutant seeds germinated easily even in a shorter period of storage than wild-type seeds. The cho1 mutants showed reduced responsiveness to ABA, whereas transgenic plants constitutively expressing CHO1 (p35SCHO1) showed an opposite phenotype. Notably, after-ripening reduced the ABA responsiveness of the wild type, cho1 mutants, and p35SCHO1 lines. Hormone profiling demonstrated that after-ripening treatment decreased the levels of ABA and salicylic acid and increased GA(4), jasmonic acid, and isopentenyl adenine when wild-type seeds were imbibed. Expression analysis showed that the transcript levels of genes for ABA and GA metabolism were altered in the wild type by after-ripening. Hormone profiling and expression analyses indicate that cho1 seeds, with a short period of storage, resembled fully after-ripened wild-type seeds. Genetic analysis showed that the cho1 mutation partially restored delayed seed germination and reduced GA biosynthesis activity in the ABA-overaccumulating cyp707a2-1 mutant background but did not restore seed germination in the GA-deficient ga1-3 mutant background. These results indicate that CHO1 acts downstream of ABA to repress GA biosynthesis during seed germination.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abscisic Acid / metabolism*
  • Arabidopsis / genetics
  • Arabidopsis / growth & development*
  • Arabidopsis Proteins / chemistry
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Base Sequence
  • Electrophoretic Mobility Shift Assay
  • Gene Expression Regulation, Plant
  • Germination*
  • Gibberellins / biosynthesis*
  • Glucuronidase / metabolism
  • Homeodomain Proteins / chemistry*
  • Molecular Sequence Data
  • Mutation / genetics
  • Nuclear Proteins / chemistry*
  • Plant Growth Regulators / metabolism
  • Protein Structure, Tertiary
  • Regulatory Sequences, Nucleic Acid / genetics
  • Repetitive Sequences, Amino Acid
  • Seeds / genetics
  • Seeds / growth & development*
  • Seeds / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*


  • AINTEGUMENTA protein, Arabidopsis
  • APETALA2 protein, Arabidopsis
  • Arabidopsis Proteins
  • CHO1 protein, Arabidopsis
  • Gibberellins
  • Homeodomain Proteins
  • Nuclear Proteins
  • Plant Growth Regulators
  • Transcription Factors
  • Abscisic Acid
  • Glucuronidase