Mutations in two non-canonical Arabidopsis SWI2/SNF2 chromatin remodeling ATPases cause embryogenesis and stem cell maintenance defects

Plant J. 2012 Dec;72(6):1000-14. doi: 10.1111/tpj.12009. Epub 2012 Oct 22.


SWI2/SNF2 chromatin remodeling ATPases play important roles in plant and metazoan development. Whereas metazoans generally encode one or two SWI2/SNF2 ATPase genes, Arabidopsis encodes four such chromatin regulators: the well-studied BRAHMA and SPLAYED ATPases, as well as two closely related non-canonical SWI2/SNF2 ATPases, CHR12 and CHR23. No developmental role has as yet been described for CHR12 and CHR23. Here, we show that although strong single chr12 or chr23 mutants are morphologically indistinguishable from the wild type, chr12 chr23 double mutants cause embryonic lethality. The double mutant embryos fail to initiate root and shoot meristems, and display few and aberrant cell divisions. Weak double mutant embryos give rise to viable seedlings with dramatic defects in the maintenance of both the shoot and the root stem cell populations. Paradoxically, the stem cell defects are correlated with increased expression of the stem cell markers WUSCHEL and WOX5. During subsequent development, the meristem defects are partially overcome to allow for the formation of very small, bushy adult plants. Based on the observed morphological defects, we named the two chromatin remodelers MINUSCULE 1 and 2. Possible links between minu1 minu2 defects and defects in hormone signaling and replication-coupled chromatin assembly are discussed.

Keywords: SWI2/SNF2 subgroup ATPases; chromatin remodeling; embryogenesis; root meristem; shoot meristem; stem cell maintenance.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adenosine Triphosphatases / genetics*
  • Adenosine Triphosphatases / metabolism
  • Alleles
  • Arabidopsis / cytology
  • Arabidopsis / embryology
  • Arabidopsis / genetics*
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / metabolism
  • Chromatin / metabolism
  • Chromatin Assembly and Disassembly
  • Gene Expression Regulation, Plant*
  • Genes, Reporter
  • Meristem / cytology
  • Meristem / embryology
  • Meristem / genetics
  • Mutation
  • Phenotype
  • Plant Roots / cytology
  • Plant Roots / embryology
  • Plant Roots / genetics
  • Stem Cells
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism


  • Arabidopsis Proteins
  • CHR12 protein, Arabidopsis
  • Chromatin
  • Transcription Factors
  • Adenosine Triphosphatases
  • CHR23 protein, Arabidopsis