Cell expansion-mediated organ growth is affected by mutations in three EXIGUA genes

PLoS One. 2012;7(5):e36500. doi: 10.1371/journal.pone.0036500. Epub 2012 May 4.


Organ growth depends on two distinct, yet integrated, processes: cell proliferation and post-mitotic cell expansion. Although the regulatory networks of plant cell proliferation during organ growth have begun to be unveiled, the mechanisms regulating post-mitotic cell growth remain mostly unknown. Here, we report the characterization of three EXIGUA (EXI) genes that encode different subunits of the cellulose synthase complex specifically required for secondary cell wall formation. Despite this highly specific role of EXI genes, all the cells within the leaf, even those that do not have secondary walls, display small sizes in the exi mutants. In addition, we found a positive correlation between cell size and the DNA ploidy levels in exi mutant leaves, suggesting that both processes share some regulatory components. Our results are consistent with the hypothesis that the collapsed xylem vessels of the exi mutants hamper water transport throughout the plant, which, in turn, limits the turgor pressure levels required for normal post-mitotic cell expansion during leaf growth.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / growth & development*
  • Arabidopsis Proteins* / genetics
  • Arabidopsis Proteins* / metabolism
  • Cell Proliferation
  • Cell Wall* / genetics
  • Cell Wall* / metabolism
  • Cell Wall* / ultrastructure
  • Gene Expression Regulation, Plant
  • Glucosyltransferases* / genetics
  • Glucosyltransferases* / metabolism
  • Mitosis
  • Mutation
  • Osmotic Pressure
  • Plant Leaves / genetics
  • Plant Leaves / growth & development*
  • Plant Stems / genetics
  • Plant Stems / growth & development*
  • Water / metabolism
  • Xylem / genetics
  • Xylem / growth & development


  • Arabidopsis Proteins
  • IRX3 protein, Arabidopsis
  • Water
  • CESA8 protein, Arabidopsis
  • Glucosyltransferases