title: Silencing of the GDP-D-mannose 3,5-epimerase affects the structure and cross-linking of the pectic polysaccharide rhamnogalacturonan II and plant growth in tomato.
abstract: L-galactose (L-Gal), a monosaccharide involved in L-ascorbate and rhamnogalacturonan II (RG-II) biosynthesis in plants, is produced in the cytosol by a GDP-D-mannose 3,5-epimerase (GME). It has been recently reported that the partial inactivation of GME induced growth defects affecting both cell division and cell expansion (Gilbert, L., Alhagdow, M., Nunes-Nesi, A., Quemener, B., Guillon, F., Bouchet, B., Faurobert, M., Gouble, B., Page, D., Garcia, V., Petit, J., Stevens, R., Causse, M., Fernie, A. R., Lahaye, M., Rothan, C., and Baldet, P. (2009) Plant J. 60, 499-508). In the present study, we show that the silencing of the two GME genes in tomato leaves resulted in approximately a 60% decrease in terminal L-Gal content in the side chain A of RG-II as well as in a lower capacity of RG-II to perform in muro cross-linking. In addition, we show that unlike supplementation with L-Gal or ascorbate, supplementation of GME-silenced lines with boric acid was able to restore both the wild-type growth phenotype of tomato seedlings and an efficient in muro boron-mediated cross-linking of RG-II. Our findings suggest that developmental phenotypes in GME-deficient lines are due to the structural alteration of RG-II and further underline the crucial role of the cross-linking of RG-II in the formation of the pectic network required for normal plant growth and development.
authors.affiliation: From the Laboratoire Glycobiologie et Matrice Extracellulaire Végétale, Equipe Associée 4358, Institut Fédératif de Recherche 23, Université de Rouen, 76821 Mont-Saint-Aignan, France.
authors.forename: Aline
authors.initials: A
authors.lastname: Voxeur
authors.affiliation: the Unité Mixte de Recherche 619 Biologie du Fruit, Institut National de Recherche Agronomique, Institut Fédératif de Recherche 103, Université de Bordeaux, BP 81, 33883 Villenave d'Ornon cedex, France.
authors.forename: Louise
authors.initials: L
authors.lastname: Gilbert
authors.affiliation: the Unité Mixte de Recherche 6270, Institut Fédératif de Recherche 23, Université de Rouen, 76821 Mont-Saint-Aignan, France, and.
authors.forename: Christophe
authors.initials: C
authors.lastname: Rihouey
authors.affiliation: From the Laboratoire Glycobiologie et Matrice Extracellulaire Végétale, Equipe Associée 4358, Institut Fédératif de Recherche 23, Université de Rouen, 76821 Mont-Saint-Aignan, France.
authors.forename: Azeddine
authors.initials: A
authors.lastname: Driouich
authors.affiliation: the Unité Mixte de Recherche 619 Biologie du Fruit, Institut National de Recherche Agronomique, Institut Fédératif de Recherche 103, Université de Bordeaux, BP 81, 33883 Villenave d'Ornon cedex, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Rothan
authors.affiliation: the Unité Mixte de Recherche 619 Biologie du Fruit, Institut National de Recherche Agronomique, Institut Fédératif de Recherche 103, Université de Bordeaux, BP 81, 33883 Villenave d'Ornon cedex, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Baldet
authors.affiliation: From the Laboratoire Glycobiologie et Matrice Extracellulaire Végétale, Equipe Associée 4358, Institut Fédératif de Recherche 23, Université de Rouen, 76821 Mont-Saint-Aignan, France,. Electronic address: patrice.lerouge@univ-rouen.fr.
authors.forename: Patrice
authors.initials: P
authors.lastname: Lerouge
mesh_terms: D002236:Carbohydrate Conformation; D002238:Carbohydrate Epimerases / Q000235:genetics / Q000378:metabolism*; D020868:Gene Silencing; D017343:Genes, Plant / Q000502:physiology; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D010368:Pectins / Q000096:biosynthesis* / Q000235:genetics; D018515:Plant Leaves / Q000201:enzymology* / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; C042492:rhamnogalacturonan II; D010368:Pectins; D002238:Carbohydrate Epimerases; C019192:GDPmannose 3,5-epimerase