Re-induction of the cell cycle in the Arabidopsis post-embryonic root meristem is ABA-insensitive, GA-dependent and repressed by KRP6

Research output: Contribution to journalArticle


  • Jeroen Nieuwland
  • Petra Stamm
  • Bo Wen
  • Ricardo S Randall
  • James A H Murray

Colleges, School and Institutes

External organisations

  • Cardiff University
  • School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom.


Seeding establishment following seed germination requires activation of the root meristem for primary root growth. We investigated the hormonal and genetic regulation of root meristem activation during Arabidopsis seed germination. In optimal conditions, radicle cell divisions occur only after the completion of germination and require de novo GA synthesis. When the completion of germination is blocked by ABA, radicle elongation and cell divisions occurred in these non-germinating seeds. Conversely under GA-limiting conditions, ABA-insensitive mutants complete germination in the absence of radicle meristem activation and growth. Radicle meristem activation and extension can therefore occur independently of completion of the developmental transition of germination. The cell cycle regulator KRP6 partially represses GA-dependent activation of the cell cycle. Germination of krp6 mutant seeds occurs more rapidly, is slightly insensitive to ABA in dose-response assays, but also hypersensitive to the GA synthesis inhibitor PAC. These conflicting phenotypes suggest the cell cycle uncouples GA and ABA responses in germinating Arabidopsis seeds, and that KRP6 acts downstream of GA to inhibit mitotic cell cycle activation during germination.


Original languageEnglish
Article number23586
JournalScientific Reports
Publication statusPublished - 29 Mar 2016


  • Abscisic Acid, Arabidopsis, Arabidopsis Proteins, Carrier Proteins, Cell Cycle, Gene Expression Regulation, Plant, Germination, Gibberellins, Meristem, Microscopy, Confocal, Mutation, Plant Growth Regulators, Plant Roots, Plants, Genetically Modified, Reverse Transcriptase Polymerase Chain Reaction, Seedlings, Seeds, Signal Transduction, Journal Article, Research Support, Non-U.S. Gov't