title: Pectin-induced changes in cell wall mechanics underlie organ initiation in Arabidopsis.
abstract: Tissue mechanics have been shown to play a key role in the regulation of morphogenesis in animals [1-4] and may have an equally important role in plants [5-9]. The aerial organs of plants are formed at the shoot apical meristem following a specific phyllotactic pattern [10]. The initiation of an organ from the meristem requires a highly localized irreversible surface deformation, which depends on the demethylesterification of cell wall pectins [11]. Here, we used atomic force microscopy (AFM) to investigate whether these chemical changes lead to changes in tissue mechanics. By mapping the viscoelasticity and elasticity in living meristems, we observed increases in tissue elasticity, correlated with pectin demethylesterification, in primordia and at the site of incipient organs. Measurements of tissue elasticity at various depths showed that, at the site of incipient primordia, the first increases occurred in subepidermal tissues. The results support the following causal sequence of events: (1) demethylesterification of pectin is triggered in subepidermal tissue layers, (2) this contributes to an increase in elasticity of these layers-the first observable mechanical event in organ initiation, and (3) the process propagates to the epidermis during the outgrowth of the organ.
authors: Institut Jean-Pierre Bourgin, UMR1318 INRA-AgroParisTech, 78026 Versailles, France. alexis.peaucelle@versailles.inra.fr
authors: Alexis
authors: A
authors: Peaucelle
authors: Siobhan A
authors: SA
authors: Braybrook
authors: Laurent
authors: L
authors: Le Guillou
authors: Emeric
authors: E
authors: Bron
authors: Cris
authors: C
authors: Kuhlemeier
authors: Herman
authors: H
authors: Höfte
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002265:Carboxylic Ester Hydrolases / Q000235:genetics / Q000378:metabolism; D002473:Cell Wall / Q000737:chemistry* / Q000378:metabolism*; D004548:Elasticity; D055595:Mechanical Phenomena; D018519:Meristem / Q000166:cytology* / Q000378:metabolism; D018625:Microscopy, Atomic Force; D010368:Pectins / Q000378:metabolism*; D019441:Plant Epidermis / Q000166:cytology / Q000254:growth & development / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D010368:Pectins; D002265:Carboxylic Ester Hydrolases; C022323:pectinesterase