title: Association of specific expansins with growth in maize leaves is maintained under environmental, genetic, and developmental sources of variation.
abstract: We aimed to evaluate whether changes in maize (Zea mays) leaf expansion rate in response to environmental stimuli or developmental gradients are mediated by common or specific expansins, a class of proteins known to enhance cell wall extensibility. Among the 33 maize expansin or putative expansin genes analyzed, 19 were preferentially expressed at some point of the leaf elongation zone and these expansins could be organized into three clusters related to cell division, maximal leaf expansion, and cell wall differentiation. Further analysis of the spatial distribution of expression was carried out for three expansins in leaves displaying a large range of expansion rates due to water deficit, genotype, and leaf developmental stage. With most sources of variation, the three genes showed similar changes in expression and consistent association with changes in leaf expansion. Moreover, our analysis also suggested preferential association of each expansin with elongation, widening, or both of these processes. Finally, using in situ hybridization, expression of two of these genes was increased in load-bearing tissues such as the epidermis and differentiating xylem. Together, these results suggest that some expansins may be preferentially related to elongation and widening after integrating several spatial, environmental, genetic, and developmental cues.
authors.affiliation: Laboratoire d'Ecophysiologie des Plantes sous Stress Environmentaux, Unité Mixte de Recherche 759, Institut National de la Recherche Agronomique, Ecole Nationale Supérieure Agronomique, F-34060 Montpellier, France. bertrand.muller@montpellier.inra.fr
authors.forename: Bertrand
authors.initials: B
authors.lastname: Muller
authors.forename: Gildas
authors.initials: G
authors.lastname: Bourdais
authors.forename: Beat
authors.initials: B
authors.lastname: Reidy
authors.forename: Christelle
authors.initials: C
authors.lastname: Bencivenni
authors.forename: Agnès
authors.initials: A
authors.lastname: Massonneau
authors.forename: Pascal
authors.initials: P
authors.lastname: Condamine
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Rolland
authors.forename: Geneviève
authors.initials: G
authors.lastname: Conéjéro
authors.forename: Peter
authors.initials: P
authors.lastname: Rogowsky
authors.forename: François
authors.initials: F
authors.lastname: Tardieu
mesh_terms: D002454:Cell Differentiation; D002455:Cell Division; D002473:Cell Wall / Q000378:metabolism / Q000648:ultrastructure; D016000:Cluster Analysis; D005838:Genotype; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D014867:Water / Q000378:metabolism; D052584:Xylem / Q000378:metabolism; D003313:Zea mays / Q000166:cytology / Q000254:growth & development / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; C095825:expansin protein, plant; D014867:Water