title: Resolving the Role of Plant NAD-Glutamate Dehydrogenase: III. Overexpressing Individually or Simultaneously the Two Enzyme Subunits Under Salt Stress Induces Changes in the Leaf Metabolic Profile and Increases Plant Biomass Production.
abstract: NAD-dependent glutamate dehydrogenase (NAD-GDH) of higher plants has a central position at the interface between carbon and nitrogen metabolism due to its ability to carry out the deamination of glutamate. In order to obtain a better understanding of the physiological function of NAD-GDH under salt stress conditions, transgenic tobacco (Nicotiana tabacum L.) plants that overexpress two genes from Nicotiana plumbaginifolia individually (GDHA and GDHB) or simultaneously (GDHA/B) were grown in the presence of 50 mM NaCl. In the different GDH overexpressors, the NaCl treatment induced an additional increase in GDH enzyme activity, indicating that a post-transcriptional mechanism regulates the final enzyme activity under salt stress conditions. A greater shoot and root biomass production was observed in the three types of GDH overexpressors following growth in 50 mM NaCl, when compared with the untransformed plants subjected to the same salinity stress. Changes in metabolites representative of the plant carbon and nitrogen status were also observed. They were mainly characterized by an increased amount of starch present in the leaves of the GDH overexpressors as compared with the wild type when plants were grown in 50 mM NaCl. Metabolomic analysis revealed that overexpressing the two genes GDHA and GDHB, individually or simultaneously, induced a differential accumulation of several carbon- and nitrogen-containing molecules involved in a variety of metabolic, developmental and stress-responsive processes. An accumulation of digalactosylglycerol, erythronate and porphyrin was found in the GDHA, GDHB and GDHA/B overexpressors, suggesting that these molecules could contribute to the improved performance of the transgenic plants under salinity stress conditions.
authors.affiliation: Adaptation des Plantes à leur Environnement, Unité Mixte de Recherche 1318, Institut Jean-Pierre Bourgin, Saclay Plant Sciences, Institut National de la Recherche Agronomique (INRA), Centre de Versailles-Grignon, RD 10, 78026 Versailles cedex, France.
authors.forename: Thérèse
authors.initials: T
authors.lastname: Tercé-Laforgue
authors.affiliation: Adaptation des Plantes à leur Environnement, Unité Mixte de Recherche 1318, Institut Jean-Pierre Bourgin, Saclay Plant Sciences, Institut National de la Recherche Agronomique (INRA), Centre de Versailles-Grignon, RD 10, 78026 Versailles cedex, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Clément
authors.affiliation: Dipartimento di Bioscienze, Università di Parma, Parco Area delle Scienze 11/A, 43100 Parma, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Marchi
authors.affiliation: Dipartimento di Bioscienze, Università di Parma, Parco Area delle Scienze 11/A, 43100 Parma, Italy.
authors.forename: Francesco M
authors.initials: FM
authors.lastname: Restivo
authors.affiliation: Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Lea
authors.affiliation: Adaptation des Plantes à leur Environnement, Unité Mixte de Recherche 1318, Institut Jean-Pierre Bourgin, Saclay Plant Sciences, Institut National de la Recherche Agronomique (INRA), Centre de Versailles-Grignon, RD 10, 78026 Versailles cedex, France hirel@versailles.inra.fr.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Hirel
mesh_terms: D018533:Biomass; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005969:Glutamate Dehydrogenase / Q000378:metabolism*; D055442:Metabolome / Q000235:genetics / Q000502:physiology*; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D014026:Nicotiana / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism*
chemical_list: D012965:Sodium Chloride; D005969:Glutamate Dehydrogenase
keywords: Glutamate dehydrogenase; Metabolome; Overexpression; Salt stress. Subunit; Tobacco