Arabidopsis phyllotaxis is controlled by the methyl-esterification status of cell-wall pectins

Curr Biol. 2008 Dec 23;18(24):1943-8. doi: 10.1016/j.cub.2008.10.065.

Abstract

Plant organs are produced from meristems in a characteristic pattern. This pattern, referred to as phyllotaxis, is thought to be generated by local gradients of an information molecule, auxin. Some studies propose a key role for the mechanical properties of the cell walls in the control of organ outgrowth. A major cell-wall component is the linear alpha-1-4-linked D-GalAp pectic polysaccharide homogalacturonan (HG), which plays a key role in cell-to-cell cohesion. HG is deposited in the cell wall in a highly (70%-80%) methyl-esterified form and is subsequently de-methyl-esterified by pectin methyl-esterases (PME, EC 3.1.1.11). PME activity is itself regulated by endogenous PME inhibitor (PMEI) proteins. PME action modulates cell-wall-matrix properties and plays a role in the control of cell growth. Here, we show that the formation of flower primordia in the Arabidopsis shoot apical meristem is accompanied by the de-methyl-esterification of pectic polysaccharides in the cell walls. In addition, experimental perturbation of the methyl-esterification status of pectins within the meristem dramatically alters the phyllotactic pattern. These results demonstrate that regulated de-methyl-esterification of pectins is a key event in the outgrowth of primordia and possibly also in phyllotactic patterning.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / growth & development*
  • Arabidopsis / metabolism*
  • Body Patterning / physiology
  • Carboxylic Ester Hydrolases / genetics
  • Carboxylic Ester Hydrolases / metabolism
  • Cell Wall / metabolism
  • Esterification
  • Genes, Plant
  • Indoleacetic Acids / metabolism
  • Meristem / growth & development
  • Meristem / metabolism
  • Models, Biological
  • Multigene Family
  • Mutation
  • Pectins / chemistry*
  • Pectins / metabolism*

Substances

  • Indoleacetic Acids
  • Pectins
  • Carboxylic Ester Hydrolases
  • pectinesterase
  • polygalacturonic acid