title: Most stomatal closure in woody species under moderate drought can be explained by stomatal responses to leaf turgor.
abstract: Reduced stomatal conductance (gs ) during soil drought in angiosperms may result from effects of leaf turgor on stomata and/or factors that do not directly depend on leaf turgor, including root-derived abscisic acid (ABA) signals. To quantify the roles of leaf turgor-mediated and leaf turgor-independent mechanisms in gs decline during drought, we measured drought responses of gs and water relations in three woody species (almond, grapevine and olive) under a range of conditions designed to generate independent variation in leaf and root turgor, including diurnal variation in evaporative demand and changes in plant hydraulic conductance and leaf osmotic pressure. We then applied these data to a process-based gs model and used a novel method to partition observed declines in gs during drought into contributions from each parameter in the model. Soil drought reduced gs by 63-84% across species, and the model reproduced these changes well (r(2)  = 0.91, P < 0.0001, n = 44) despite having only a single fitted parameter. Our analysis concluded that responses mediated by leaf turgor could explain over 87% of the observed decline in gs across species, adding to a growing body of evidence that challenges the root ABA-centric model of stomatal responses to drought.
authors.affiliation: Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes 10, 41012, Seville, Spain.|Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Seville, Spain.
authors.forename: Celia M
authors.identifier: 0000-0003-2352-0829
authors.initials: CM
authors.lastname: Rodriguez-Dominguez
authors.affiliation: IA Watson Grains Research Centre, Plant Breeding Institute, Faculty of Agriculture and Environment, The University of Sydney, Narrabri, NSW, 2390, Australia.
authors.forename: Thomas N
authors.initials: TN
authors.lastname: Buckley
authors.affiliation: Área de Ingeniería Agroforestal, Escuela Técnica Superior de Ingeniería Agronómica, Universidad de Sevilla, Ctra Utrera, km 1, 41013, Seville, Spain.
authors.forename: Gregorio
authors.initials: G
authors.lastname: Egea
authors.affiliation: Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Seville, Spain.
authors.forename: Alfonso
authors.initials: A
authors.lastname: de Cires
authors.affiliation: Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes 10, 41012, Seville, Spain.
authors.forename: Virginia
authors.initials: V
authors.lastname: Hernandez-Santana
authors.affiliation: Research Group on Plant Biology under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears, Carretera de Valldemossa Km 7.5, 07122, Palma, Illes Balears, Spain.
authors.forename: Sebastia
authors.initials: S
authors.lastname: Martorell
authors.affiliation: Irrigation and Crop Ecophysiology Group, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS, CSIC), Avenida Reina Mercedes 10, 41012, Seville, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Diaz-Espejo
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D055864:Droughts; D008954:Models, Biological; D031658:Olea; D054046:Plant Stomata / Q000502:physiology*; D000068181:Prunus dulcis; D027843:Vitis
chemical_list: D000040:Abscisic Acid
keywords: abscisic acid; isohydric; process-based model; stomata; stomatal limitation; transpiration; water stress