title: The dual effect of abscisic acid on stomata.
abstract: The classical view that the drought-related hormone ABA simply acts locally at the guard cell level to induce stomatal closure is questioned by differences between isolated epidermis and intact leaves in stomatal response to several stimuli. We tested the hypothesis that ABA mediates, in addition to a local effect, a remote effect in planta by changing hydraulic regulation in the leaf upstream of the stomata. By gravimetry, porometry to water vapour and argon, and psychrometry, we investigated the effect of exogenous ABA on transpiration, stomatal conductance and leaf hydraulic conductance of mutants described as ABA-insensitive at the guard cell level. We show that foliar transpiration of several ABA-insensitive mutants decreases in response to ABA. We demonstrate that ABA decreases stomatal conductance and down-regulates leaf hydraulic conductance in both the wildtype Col-0 and the ABA-insensitive mutant ost2-2. We propose that ABA promotes stomatal closure in a dual way via its already known biochemical effect on guard cells and a novel, indirect hydraulic effect through a decrease in water permeability within leaf vascular tissues. Variability in sensitivity of leaf hydraulic conductance to ABA among species could provide a physiological basis to the isohydric or anisohydric behaviour.
authors.affiliation: INRA, UMR 759, Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, 34060, Montpellier, France.
authors.forename: Florent
authors.initials: F
authors.lastname: Pantin
authors.affiliation: CEA, DSV, IBEB, Laboratoire d'Ecophysiologie Moléculaire des Plantes, 13108, Saint-Paul-lez-Durance, France.|CNRS, UMR 7265, Biologie Végétale et Microbiologie Environnementales, 13108, Saint-Paul-lez-Durance, France.|Université Aix-Marseille, 13108, Saint-Paul-lez-Durance, France.|Université d'Avignon et des Pays de Vaucluse, 84000, Avignon, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Monnet
authors.affiliation: CEA, DSV, IBEB, Laboratoire d'Ecophysiologie Moléculaire des Plantes, 13108, Saint-Paul-lez-Durance, France.|CNRS, UMR 7265, Biologie Végétale et Microbiologie Environnementales, 13108, Saint-Paul-lez-Durance, France.|Université Aix-Marseille, 13108, Saint-Paul-lez-Durance, France.
authors.forename: Dorothée
authors.initials: D
authors.lastname: Jannaud
authors.affiliation: CEA, DSV, IBEB, Laboratoire d'Ecophysiologie Moléculaire des Plantes, 13108, Saint-Paul-lez-Durance, France.|CNRS, UMR 7265, Biologie Végétale et Microbiologie Environnementales, 13108, Saint-Paul-lez-Durance, France.|Université Aix-Marseille, 13108, Saint-Paul-lez-Durance, France.
authors.forename: Joaquim Miguel
authors.initials: JM
authors.lastname: Costa
authors.affiliation: INRA, UMR 759, Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, 34060, Montpellier, France.
authors.forename: Jeanne
authors.initials: J
authors.lastname: Renaud
authors.affiliation: INRA, UMR 759, Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, 34060, Montpellier, France.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Muller
authors.affiliation: INRA, UMR 759, Laboratoire d'Ecophysiologie des Plantes sous Stress Environnementaux, 34060, Montpellier, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Simonneau
authors.affiliation: CEA, DSV, IBEB, Laboratoire d'Ecophysiologie Moléculaire des Plantes, 13108, Saint-Paul-lez-Durance, France.|CNRS, UMR 7265, Biologie Végétale et Microbiologie Environnementales, 13108, Saint-Paul-lez-Durance, France.|Université Aix-Marseille, 13108, Saint-Paul-lez-Durance, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Genty
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D001128:Argon / Q000378:metabolism; D001692:Biological Transport; D055864:Droughts; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism; D059828:Plant Cells / Q000378:metabolism*; D019441:Plant Epidermis / Q000187:drug effects / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D054046:Plant Stomata / Q000187:drug effects* / Q000378:metabolism; D018526:Plant Transpiration / Q000187:drug effects; D014867:Water / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D014867:Water; D001128:Argon; D000040:Abscisic Acid; C087434:ABI1 protein, Arabidopsis; C106443:ABI2 protein, Arabidopsis; D010749:Phosphoprotein Phosphatases