title: Two tomato GDP-D-mannose epimerase isoforms involved in ascorbate biosynthesis play specific roles in cell wall biosynthesis and development.
abstract: GDP-D-mannose epimerase (GME, EC 5.1.3.18) converts GDP-D-mannose to GDP-L-galactose, and is considered to be a central enzyme connecting the major ascorbate biosynthesis pathway to primary cell wall metabolism in higher plants. Our previous work demonstrated that GME is crucial for both ascorbate and cell wall biosynthesis in tomato. The aim of the present study was to investigate the respective role in ascorbate and cell wall biosynthesis of the two SlGME genes present in tomato by targeting each of them through an RNAi-silencing approach. Taken individually SlGME1 and SlGME2 allowed normal ascorbate accumulation in the leaf and fruits, thus suggesting the same function regarding ascorbate. However, SlGME1 and SlGME2 were shown to play distinct roles in cell wall biosynthesis, depending on the tissue considered. The RNAi-SlGME1 plants harbored small and poorly seeded fruits resulting from alterations of pollen development and of pollination process. In contrast, the RNAi-SlGME2 plants exhibited vegetative growth delay while fruits remained unaffected. Analysis of SlGME1- and SlGME2-silenced seeds and seedlings further showed that the dimerization state of pectin rhamnogalacturonan-II (RG-II) was altered only in the RNAi-SlGME2 lines. Taken together with the preferential expression of each SlGME gene in different tomato tissues, these results suggest sub-functionalization of SlGME1 and SlGME2 and their specialization for cell wall biosynthesis in specific tomato tissues.
authors.affiliation: Institut National de la Recherche Agronomique (INRA), Université de Bordeaux, Unité Mixte de Recherche 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon Cedex, France.
authors.forename: Louise
authors.initials: L
authors.lastname: Mounet-Gilbert
authors.affiliation: Normandy University, Université de Rouen, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale, EA4358, IRIB, VASI, 76821 Mont-Saint-Aignan, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Dumont
authors.affiliation: Institut National de la Recherche Agronomique (INRA), Université de Bordeaux, Unité Mixte de Recherche 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon Cedex, France.
authors.forename: Carine
authors.initials: C
authors.lastname: Ferrand
authors.affiliation: Institut National de la Recherche Agronomique (INRA), Université de Bordeaux, Unité Mixte de Recherche 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon Cedex, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Bournonville
authors.affiliation: Institut National de la Recherche Agronomique (INRA), Université de Bordeaux, Unité Mixte de Recherche 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon Cedex, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Monier
authors.affiliation: Institut National de la Recherche Agronomique (INRA), Université de Bordeaux, Unité Mixte de Recherche 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon Cedex, France.
authors.forename: Joana
authors.initials: J
authors.lastname: Jorly
authors.affiliation: Institut National de la Recherche Agronomique (INRA), Université de Bordeaux, Unité Mixte de Recherche 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon Cedex, France.
authors.forename: Martine
authors.initials: M
authors.lastname: Lemaire-Chamley
authors.affiliation: Institut National de la Recherche Agronomique (INRA), Université de Bordeaux, Unité Mixte de Recherche 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon Cedex, France.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Mori
authors.affiliation: Institut National de la Recherche Agronomique (INRA), Université de Bordeaux, Unité Mixte de Recherche 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon Cedex, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Atienza
authors.affiliation: Institut National de la Recherche Agronomique (INRA), Université de Bordeaux, Unité Mixte de Recherche 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon Cedex, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Hernould
authors.affiliation: Institut National de la Recherche Agronomique (INRA), Unité de Recherche 1052 Génétique et Amélioration des Fruits et Légumes, Domaine Saint Maurice, 67, Allée des Chênes, CS 60094 F-84143 Montfavet Cedex, France.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Stevens
authors.affiliation: Normandy University, Université de Rouen, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale, EA4358, IRIB, VASI, 76821 Mont-Saint-Aignan, France.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Lehner
authors.affiliation: Normandy University, Université de Rouen, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale, EA4358, IRIB, VASI, 76821 Mont-Saint-Aignan, France.
authors.forename: Jean Claude
authors.initials: JC
authors.lastname: Mollet
authors.affiliation: Institut National de la Recherche Agronomique (INRA), Université de Bordeaux, Unité Mixte de Recherche 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon Cedex, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Rothan
authors.affiliation: Normandy University, Université de Rouen, Laboratoire Glycobiologie et Matrice Extracellulaire Végétale, EA4358, IRIB, VASI, 76821 Mont-Saint-Aignan, France.
authors.forename: Patrice
authors.initials: P
authors.lastname: Lerouge
authors.affiliation: Institut National de la Recherche Agronomique (INRA), Université de Bordeaux, Unité Mixte de Recherche 1332 Biologie du Fruit et Pathologie, CS20032, F-33882 Villenave d'Ornon Cedex, France pierre.baldet@bordeaux.inra.fr.
authors.forename: Pierre
authors.initials: P
authors.lastname: Baldet
mesh_terms: D001205:Ascorbic Acid / Q000096:biosynthesis*; D002238:Carbohydrate Epimerases / Q000378:metabolism* / Q000502:physiology; D002473:Cell Wall / Q000378:metabolism* / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D018525:Germination / Q000502:physiology; D007527:Isoenzymes / Q000378:metabolism / Q000502:physiology; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D011058:Pollen / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D002238:Carbohydrate Epimerases; C019192:GDPmannose 3,5-epimerase; D001205:Ascorbic Acid
keywords: Ascorbate; GDP-D-mannose epimerase; Solanum lycopersicum; cell wall; growth; rhamnogalacturonan-II; tomato fruits.