COBRA-LIKE2, a member of the glycosylphosphatidylinositol-anchored COBRA-LIKE family, plays a role in cellulose deposition in arabidopsis seed coat mucilage secretory cells

Plant Physiol. 2015 Mar;167(3):711-24. doi: 10.1104/pp.114.240671. Epub 2015 Jan 12.


Differentiation of the maternally derived seed coat epidermal cells into mucilage secretory cells is a common adaptation in angiosperms. Recent studies identified cellulose as an important component of seed mucilage in various species. Cellulose is deposited as a set of rays that radiate from the seed upon mucilage extrusion, serving to anchor the pectic component of seed mucilage to the seed surface. Using transcriptome data encompassing the course of seed development, we identified COBRA-LIKE2 (COBL2), a member of the glycosylphosphatidylinositol-anchored COBRA-LIKE gene family in Arabidopsis (Arabidopsis thaliana), as coexpressed with other genes involved in cellulose deposition in mucilage secretory cells. Disruption of the COBL2 gene results in substantial reduction in the rays of cellulose present in seed mucilage, along with an increased solubility of the pectic component of the mucilage. Light birefringence demonstrates a substantial decrease in crystalline cellulose deposition into the cellulosic rays of the cobl2 mutants. Moreover, crystalline cellulose deposition into the radial cell walls and the columella appears substantially compromised, as demonstrated by scanning electron microscopy and in situ quantification of light birefringence. Overall, the cobl2 mutants display about 40% reduction in whole-seed crystalline cellulose content compared with the wild type. These data establish that COBL2 plays a role in the deposition of crystalline cellulose into various secondary cell wall structures during seed coat epidermal cell differentiation.

Publication types

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

MeSH terms

  • Arabidopsis / cytology*
  • Arabidopsis / drug effects
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Birefringence
  • Cations
  • Cell Differentiation / drug effects
  • Cell Wall / drug effects
  • Cell Wall / metabolism
  • Cellulose / metabolism*
  • Chelating Agents / pharmacology
  • Crystallization
  • Gene Expression Regulation, Plant / drug effects
  • Glycosylphosphatidylinositols / metabolism*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mutation
  • Organ Specificity / drug effects
  • Pectins / metabolism
  • Plant Epidermis / cytology
  • Plant Epidermis / drug effects
  • Plant Mucilage / metabolism
  • Seeds / cytology*
  • Seeds / genetics
  • Seeds / growth & development
  • Seeds / ultrastructure
  • Solubility


  • Arabidopsis Proteins
  • COBL2 protein, Arabidopsis
  • Cations
  • Chelating Agents
  • Glycosylphosphatidylinositols
  • Membrane Proteins
  • Plant Mucilage
  • Pectins
  • Cellulose