title: Arabidopsis plants acclimate to water deficit at low cost through changes of carbon usage: an integrated perspective using growth, metabolite, enzyme, and gene expression analysis.
abstract: Growth and carbon (C) fluxes are severely altered in plants exposed to soil water deficit. Correspondingly, it has been suggested that plants under water deficit suffer from C shortage. In this study, we test this hypothesis in Arabidopsis (Arabidopsis thaliana) by providing an overview of the responses of growth, C balance, metabolites, enzymes of the central metabolism, and a set of sugar-responsive genes to a sustained soil water deficit. The results show that under drought, rosette relative expansion rate is decreased more than photosynthesis, leading to a more positive C balance, while root growth is promoted. Several soluble metabolites accumulate in response to soil water deficit, with K(+) and organic acids as the main contributors to osmotic adjustment. Osmotic adjustment costs only a small percentage of the daily photosynthetic C fixation. All C metabolites measured (not only starch and sugars but also organic acids and amino acids) show a diurnal turnover that often increased under water deficit, suggesting that these metabolites are readily available for being metabolized in situ or exported to roots. On the basis of 30 enzyme activities, no in-depth reprogramming of C metabolism was observed. Water deficit induces a shift of the expression level of a set of sugar-responsive genes that is indicative of increased, rather than decreased, C availability. These results converge to show that the differential impact of soil water deficit on photosynthesis and rosette expansion results in an increased availability of C for the roots, an increased turnover of C metabolites, and a low-cost C-based osmotic adjustment, and these responses are performed without major reformatting of the primary metabolism machinery.
authors.affiliation: INRA, Ecophysiologie des Plantes sous Stress Environnementaux, UMR 759, Montpellier, France.
authors.forename: Irène
authors.initials: I
authors.lastname: Hummel
authors.forename: Florent
authors.initials: F
authors.lastname: Pantin
authors.forename: Ronan
authors.initials: R
authors.lastname: Sulpice
authors.forename: Maria
authors.initials: M
authors.lastname: Piques
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Rolland
authors.forename: Myriam
authors.initials: M
authors.lastname: Dauzat
authors.forename: Angélique
authors.initials: A
authors.lastname: Christophe
authors.forename: Marjorie
authors.initials: M
authors.lastname: Pervent
authors.forename: Marie
authors.initials: M
authors.lastname: Bouteillé
authors.forename: Mark
authors.initials: M
authors.lastname: Stitt
authors.forename: Yves
authors.initials: Y
authors.lastname: Gibon
authors.forename: Bertrand
authors.initials: B
authors.lastname: Muller
mesh_terms: D000064:Acclimatization / Q000187:drug effects* / Q000235:genetics; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D018533:Biomass; D050260:Carbohydrate Metabolism / Q000187:drug effects / Q000235:genetics; D002244:Carbon / Q000378:metabolism*; D002264:Carboxylic Acids / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D015999:Multivariate Analysis; D009995:Osmosis / Q000187:drug effects; D017440:Photoperiod; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development; D011188:Potassium / Q000378:metabolism; D012995:Solubility / Q000187:drug effects; D013213:Starch / Q000378:metabolism; D014867:Water / Q000494:pharmacology*
chemical_list: D002264:Carboxylic Acids; D014867:Water; D002244:Carbon; D013213:Starch; D011188:Potassium