title: An integrated "omics" approach to the characterization of maize (Zea mays L.) mutants deficient in the expression of two genes encoding cytosolic glutamine synthetase.
abstract: BACKGROUND
  To identify the key elements controlling grain production in maize, it is essential to have an integrated view of the responses to alterations in the main steps of nitrogen assimilation by modification of gene expression. Two maize mutant lines (gln1.3 and gln1.4), deficient in two genes encoding cytosolic glutamine synthetase, a key enzyme involved in nitrogen assimilation, were previously characterized by a reduction of kernel size in the gln1.4 mutant and by a reduction of kernel number in the gln1.3 mutant. In this work, the differences in leaf gene transcripts, proteins and metabolite accumulation in gln1.3 and gln1.4 mutants were studied at two key stages of plant development, in order to identify putative candidate genes, proteins and metabolic pathways contributing on one hand to the control of plant development and on the other to grain production.
  
  
  RESULTS
  The most interesting finding in this study is that a number of key plant processes were altered in the gln1.3 and gln1.4 mutants, including a number of major biological processes such as carbon metabolism and transport, cell wall metabolism, and several metabolic pathways and stress responsive and regulatory elements. We also found that the two mutants share common or specific characteristics across at least two or even three of the "omics" considered at the vegetative stage of plant development, or during the grain filling period.
  
  
  CONCLUSIONS
  This is the first comprehensive molecular and physiological characterization of two cytosolic glutamine synthetase maize mutants using a combined transcriptomic, proteomic and metabolomic approach. We find that the integration of the three "omics" procedures is not straight forward, since developmental and mutant-specific levels of regulation seem to occur from gene expression to metabolite accumulation. However, their potential use is discussed with a view to improving our understanding of nitrogen assimilation and partitioning and its impact on grain production.
authors.forename: Nardjis
authors.initials: N
authors.lastname: Amiour
authors.forename: Sandrine
authors.initials: S
authors.lastname: Imbaud
authors.forename: Gilles
authors.initials: G
authors.lastname: Clément
authors.forename: Nicolas
authors.initials: N
authors.lastname: Agier
authors.forename: Michel
authors.initials: M
authors.lastname: Zivy
authors.forename: Benoît
authors.initials: B
authors.lastname: Valot
authors.forename: Thierry
authors.initials: T
authors.lastname: Balliau
authors.forename: Isabelle
authors.initials: I
authors.lastname: Quilleré
authors.forename: Thérèse
authors.initials: T
authors.lastname: Tercé-Laforgue
authors.forename: Céline
authors.initials: C
authors.lastname: Dargel-Graffin
authors.affiliation: Institut Jean-Pierre Bourgin, Institut National de la Recherche Agronomique (INRA), Centre de Versailles-Grignon, Unité Mixte de Recherche 1318 INRA-Agro-ParisTech, Equipe de Recherche Labellisée, Centre National de la Recherche Scientifique 3559, RD10, F-78026 Versailles, Cedex, France. hirel@versailles.inra.fr.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Hirel
mesh_terms: D003600:Cytosol / Q000201:enzymology*; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005974:Glutamate-Ammonia Ligase / Q000235:genetics* / Q000378:metabolism; D055432:Metabolomics; D009154:Mutation / Q000235:genetics*; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D020543:Proteome / Q000378:metabolism; D040901:Proteomics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D059467:Transcriptome / Q000235:genetics; D003313:Zea mays / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development
chemical_list: D010940:Plant Proteins; D020543:Proteome; D012333:RNA, Messenger; D005974:Glutamate-Ammonia Ligase