title: The use of metabolomics integrated with transcriptomic and proteomic studies for identifying key steps involved in the control of nitrogen metabolism in crops such as maize.
abstract: Linking plant phenotype to gene and protein expression and also to metabolite synthesis and accumulation is one of the main challenges for improving agricultural production worldwide. Such a challenge is particularly relevant to crop nitrogen use efficiency (NUE). Here, the differences in leaf gene transcript, protein, and metabolite accumulation in maize subjected to long-term nitrogen (N)-deficient growth conditions at two important stages of plant development have been studied. The impact of N deficiency was examined at the transcriptomic, proteomic, and metabolomic levels. It was found that a number of key plant biological functions were either up- or down-regulated when N was limiting, including major alterations to photosynthesis, carbon (C) metabolism, and, to a lesser extent, downstream metabolic pathways. It was also found that the impact of the N deficiency stress resembled the response of plants to a number of other biotic and abiotic stresses, in terms of transcript, protein, and metabolite accumulation. The genetic and metabolic alterations were different during the N assimilation and the grain-filling period, indicating that plant development is an important component for identifying the key elements involved in the control of plant NUE. It was also found that integration of the three 'omics' studies is not straightforward, since different levels of regulation seem to occur in a stepwise manner from gene expression to metabolite accumulation. The potential use of these 'omics' studies is discussed with a view to improve our understanding of whole plant nitrogen economics, which should have applications in breeding and agronomy.
authors.affiliation: Institut Jean-Pierre Bourgin, Institut National de la Recherche Agronomique, Centre de Versailles-Grignon, UR 511, Route de St Cyr, F-78026 Versailles Cedex,   France.
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: Patrick
authors.initials: P
authors.lastname: Armengaud
authors.forename: Isabelle
authors.initials: I
authors.lastname: Quilleré
authors.forename: Rafael
authors.initials: R
authors.lastname: Cañas
authors.forename: Thérèse
authors.initials: T
authors.lastname: Tercet-Laforgue
authors.forename: Bertrand
authors.initials: B
authors.lastname: Hirel
mesh_terms: D002853:Chromatography, Liquid; D020869:Gene Expression Profiling; D055442:Metabolome; D009584:Nitrogen / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D010940:Plant Proteins / Q000235:genetics*; D020543:Proteome / Q000235:genetics*; D053719:Tandem Mass Spectrometry; D003313:Zea mays / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D020543:Proteome; D009584:Nitrogen