title: Evidence for the involvement of hydraulic root or shoot adjustments as mechanisms underlying water deficit tolerance in two Sorghum bicolor genotypes.
abstract: Sorghum bicolor (L.) Moench is an ancient drought-tolerant crop with potential to sustain high yields even in those environments where water is limiting. Understanding the performance of this species in early phenological stages could be a useful tool for future yield improvement programs. The aim of this work was to study the response of Sorghum seedlings under water deficit conditions in two genotypes (RedLandB2 and IS9530) that are currently employed in Argentina. Morphological and physiological traits were studied to present an integrated analysis of the shoot and root responses. Although both genotypes initially developed a conserved and indistinguishable response in terms of drought tolerance parameters (growth rate, biomass reallocation, etc.), water regulation displayed different underlying strategies. To avoid water loss, both genotypes adjusted their plant hydraulic resistance at different levels: RedLandB2 regulated shoot resistance through stomata (isohydric strategy), while IS9530 controlled root resistance (anisohydric strategy). Moreover, only in IS9530 was root hydraulic conductance restricted in the presence of HgCl2, in agreement with water movement through cell-to-cell pathways and aquaporins activity. The different responses between genotypes suggest a distinct strategy at the seedling stage and add new information that should be considered when evaluating Sorghum phenotypic plasticity in changing environments.
authors.affiliation: Departamento de Biodiversidad y Biología Experimental e Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA, CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, Pabellón II, (C1428EGA) Buenos Aires, Argentina.
authors.forename: Moira R
authors.initials: MR
authors.lastname: Sutka
authors.affiliation: Departamento de Biodiversidad y Biología Experimental e Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA, CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, Pabellón II, (C1428EGA) Buenos Aires, Argentina.
authors.forename: Milena E
authors.initials: ME
authors.lastname: Manzur
authors.affiliation: Departamento de Biodiversidad y Biología Experimental e Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA, CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, Pabellón II, (C1428EGA) Buenos Aires, Argentina.
authors.forename: Victoria A
authors.initials: VA
authors.lastname: Vitali
authors.affiliation: CERZOS-CONICET, Camino La Carrindanga Km 7, (8000) Bahía Blanca, Argentina.
authors.forename: Sandra
authors.initials: S
authors.lastname: Micheletto
authors.affiliation: Departamento de Biodiversidad y Biología Experimental e Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA, CONICET-UBA), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes 2160, Ciudad Universitaria, Pabellón II, (C1428EGA) Buenos Aires, Argentina. Electronic address: amodeo@bg.fcen.uba.ar.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Amodeo
mesh_terms: D018533:Biomass; D003681:Dehydration; D055864:Droughts; D005838:Genotype; D010641:Phenotype; D018517:Plant Roots / Q000235:genetics / Q000502:physiology; D018520:Plant Shoots / Q000235:genetics / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology*; D036226:Seedlings / Q000235:genetics / Q000502:physiology; D045868:Sorghum / Q000235:genetics / Q000502:physiology*; D014867:Water / Q000502:physiology*
chemical_list: D014867:Water
keywords: Hydraulic conductance; Seedling physiology; Sorghum bicolor; Water deficit