title: Phytochrome A increases tolerance to high evaporative demand.
abstract: Stresses resulting from high transpiration demand induce adjustments in plants that lead to reductions of water loss. These adjustments, including changes in water absorption, transport and/or loss by transpiration, are crucial to normal plant development. Tomato wild type (WT) and phytochrome A (phyA)-mutant plants, fri1-1, were exposed to conditions of either low or high transpiration demand and several morphological and physiological changes were measured during stress conditions. Mutant plants rapidly wilted compared to WT plants after exposure to high evaporative demand. Root size and hydraulic conductivity did not show significant differences between genotypes, suggesting that water absorption and transport through this organ could not explain the observed phenotype. Moreover, stomatal density was similar between genotypes, whereas transpiration and stomatal conductance were both lower in mutant than in WT plants. This was accompanied by a lower stem-specific hydraulic conductivity in mutant plants, which was associated to lower xylem vessel number and transversal area in fri1-1 plants, producing a reduction in water supply to the leaves, which rapidly wilted under high evaporative demand. PhyA signaling might facilitate the adjustment to environments differing widely in water evaporative demand in part through the modulation of xylem dimensions.
authors.affiliation: IFEVA-CONICET, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Gabriela Alejandra
authors.initials: GA
authors.lastname: Auge
authors.forename: Matías Leandro
authors.initials: ML
authors.lastname: Rugnone
authors.forename: Leandro Emanuel
authors.initials: LE
authors.lastname: Cortés
authors.forename: Carina Verónica
authors.initials: CV
authors.lastname: González
authors.forename: Gabriela
authors.initials: G
authors.lastname: Zarlavsky
authors.forename: Hernán Esteban
authors.initials: HE
authors.lastname: Boccalandro
authors.forename: Rodolfo Augusto
authors.initials: RA
authors.lastname: Sánchez
mesh_terms: D000064:Acclimatization; D001692:Biological Transport / Q000502:physiology*; D014644:Genetic Variation; D005838:Genotype; D018551:Solanum lycopersicum / Q000235:genetics / Q000254:growth & development* / Q000502:physiology*; D051942:Phytochrome A / Q000378:metabolism*; D018515:Plant Leaves / Q000502:physiology; D018517:Plant Roots / Q000502:physiology; D018547:Plant Stems / Q000502:physiology; D054046:Plant Stomata / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology*; D013045:Species Specificity; D013312:Stress, Physiological; D013472:Sunlight; D014867:Water / Q000378:metabolism*; D052584:Xylem / Q000378:metabolism
chemical_list: D051942:Phytochrome A; D014867:Water