title: Arabidopsis phyllotaxis is controlled by the methyl-esterification status of cell-wall pectins.
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.
authors.affiliation: Laboratoire de Biologie Cellulaire, Institut Jean-Pierre Bourgin, INRA Centre de Versailles-Grignon, Versailles, France. alexis.peaucelle@versailles.inra.fr
authors.forename: Alexis
authors.initials: A
authors.lastname: Peaucelle
authors.forename: Romain
authors.initials: R
authors.lastname: Louvet
authors.forename: Jorunn N
authors.initials: JN
authors.lastname: Johansen
authors.forename: Herman
authors.initials: H
authors.lastname: Höfte
authors.forename: Patrick
authors.initials: P
authors.lastname: Laufs
authors.forename: Jérome
authors.initials: J
authors.lastname: Pelloux
authors.forename: Grégory
authors.initials: G
authors.lastname: Mouille
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D019521:Body Patterning / Q000502:physiology; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D004951:Esterification; D017343:Genes, Plant; D007210:Indoleacetic Acids / Q000378:metabolism; D018519:Meristem / Q000254:growth & development / Q000378:metabolism; D008954:Models, Biological; D005810:Multigene Family; D009154:Mutation; D010368:Pectins / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D007210:Indoleacetic Acids; D010368:Pectins; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase; C003181:polygalacturonic acid