title: Gradual soil water depletion results in reversible changes of gene expression, protein profiles, ecophysiology, and growth performance in Populus euphratica, a poplar growing in arid regions.
abstract: The responses of Populus euphratica Oliv. plants to soil water deficit were assessed by analyzing gene expression, protein profiles, and several plant performance criteria to understand the acclimation of plants to soil water deficit. Young, vegetatively propagated plants originating from an arid, saline field site were submitted to a gradually increasing water deficit for 4 weeks in a greenhouse and were allowed to recover for 10 d after full reirrigation. Time-dependent changes and intensity of the perturbations induced in shoot and root growth, xylem anatomy, gas exchange, and water status were recorded. The expression profiles of approximately 6,340 genes and of proteins and metabolites (pigments, soluble carbohydrates, and oxidative compounds) were also recorded in mature leaves and in roots (gene expression only) at four stress levels and after recovery. Drought successively induced shoot growth cessation, stomatal closure, moderate increases in oxidative stress-related compounds, loss of CO2 assimilation, and root growth reduction. These effects were almost fully reversible, indicating that acclimation was dominant over injury. The physiological responses were paralleled by fully reversible transcriptional changes, including only 1.5% of the genes on the array. Protein profiles displayed greater changes than transcript levels. Among the identified proteins for which expressed sequence tags were present on the array, no correlation was found between transcript and protein abundance. Acclimation to water deficit involves the regulation of different networks of genes in roots and shoots. Such diverse requirements for protecting and maintaining the function of different plant organs may render plant engineering or breeding toward improved drought tolerance more complex than previously anticipated.
authors.affiliation: Institut National de la Recherche Agronomique Nancy, Unité Mixte de Recherche 1137 Institut National de la Recherche Agronomique-Université Henri Poincaré Ecologie et Ecophysiologie Forestières, F-54280 Champenoux, France. triboulo@nancy.inra.fr
authors.forename: Marie-Béatrice
authors.initials: MB
authors.lastname: Bogeat-Triboulot
authors.forename: Mikael
authors.initials: M
authors.lastname: Brosché
authors.forename: Jenny
authors.initials: J
authors.lastname: Renaut
authors.forename: Laurent
authors.initials: L
authors.lastname: Jouve
authors.forename: Didier
authors.initials: D
authors.lastname: Le Thiec
authors.forename: Payam
authors.initials: P
authors.lastname: Fayyaz
authors.forename: Basia
authors.initials: B
authors.lastname: Vinocur
authors.forename: Erwin
authors.initials: E
authors.lastname: Witters
authors.forename: Kris
authors.initials: K
authors.lastname: Laukens
authors.forename: Thomas
authors.initials: T
authors.lastname: Teichmann
authors.forename: Arie
authors.initials: A
authors.lastname: Altman
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Hausman
authors.forename: Andrea
authors.initials: A
authors.lastname: Polle
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kangasjärvi
authors.forename: Erwin
authors.initials: E
authors.lastname: Dreyer
mesh_terms: D002980:Climate; D017753:Ecosystem; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D032107:Populus / Q000378:metabolism*; D012987:Soil / Q000032:analysis*; D014867:Water / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D012987:Soil; D014867:Water