title: Physiological and gene expression responses of sunflower (Helianthus annuus L.) plants differ according to irrigation placement.
abstract: To investigate effects of soil moisture heterogeneity on plant physiology and gene expression in roots and leaves, three treatments were implemented in sunflower plants growing with roots split between two compartments: a control (C) treatment supplying 100% of plant evapotranspiration, and two treatments receiving 50% of plant evapotranspiration, either evenly distributed to both compartments (deficit irrigation - DI) or unevenly distributed to ensure distinct wet and dry compartments (partial rootzone drying - PRD). Plants receiving the same amount of water responded differently under the two irrigation systems. After 3 days, evapotranspiration was similar in C and DI, but 20% less in PRD, concomitant with decreased leaf water potential (Ψleaf) and increased leaf xylem ABA concentration. Six water-stress responsive genes were highly induced in roots growing in the drying soil compartment of PRD plants, and their expression was best correlated with local soil water content. On the other hand, foliar gene expression differed significantly from that of the root and correlated better with xylem ABA concentration and Ψleaf. While the PRD irrigation strategy triggered stronger physiological and molecular responses, suggesting a more intense and systemic stress reaction due to local dehydration of the dry compartment of PRD plants, the DI strategy resulted in similar water savings without strongly inducing these responses. Correlating physiological and molecular responses in PRD/DI plants may provide insights into the severity and location of water deficits and may enable a better understanding of long-distance signalling mechanisms.
authors.affiliation: IFAPA Las Torres-Tomejil, Carretera Sevilla-Cazalla Km 12.2, Alcalá del Río, 41200 Sevilla, Spain; Unidad Asociada al CSIC "Sostenibilidad de los recursos naturales agua y suelo en agroecosistemas áridos y semiáridos" (IFAPA Las Torres-Tomejil-IRNAS), Sevilla, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Aguado
authors.affiliation: IFAPA Las Torres-Tomejil, Carretera Sevilla-Cazalla Km 12.2, Alcalá del Río, 41200 Sevilla, Spain; Unidad Asociada al CSIC "Sostenibilidad de los recursos naturales agua y suelo en agroecosistemas áridos y semiáridos" (IFAPA Las Torres-Tomejil-IRNAS), Sevilla, Spain.
authors.forename: Nieves
authors.initials: N
authors.lastname: Capote
authors.affiliation: IFAPA Las Torres-Tomejil, Carretera Sevilla-Cazalla Km 12.2, Alcalá del Río, 41200 Sevilla, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Romero
authors.affiliation: The Lancaster Environment Centre, Lancaster University, LA1 4YQ, UK. Electronic address: I.Dodd@lancaster.ac.uk.
authors.forename: Ian C
authors.initials: IC
authors.lastname: Dodd
authors.affiliation: Instituto de Recursos Naturales y Agrobiologia (IRNAS), Consejo Superior de Investigaciones Científicas (CSIC), Av. Reina Mercedes 10, 41012 Sevilla, Spain; Unidad Asociada al CSIC "Sostenibilidad de los recursos naturales agua y suelo en agroecosistemas áridos y semiáridos" (IFAPA Las Torres-Tomejil-IRNAS), Sevilla, Spain. Electronic address: chemacf@irnase.csic.es.
authors.forename: José M
authors.initials: JM
authors.lastname: Colmenero-Flores
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D000222:Adaptation, Physiological / Q000235:genetics; D057914:Agricultural Irrigation / Q000379:methods; D003890:Desiccation; D015870:Gene Expression; D017343:Genes, Plant; D006368:Helianthus / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D018515:Plant Leaves / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism*; D018526:Plant Transpiration; D012987:Soil; D013312:Stress, Physiological / Q000235:genetics*; D014867:Water / Q000378:metabolism*; D052584:Xylem / Q000378:metabolism
chemical_list: D012987:Soil; D014867:Water; D000040:Abscisic Acid
keywords: ABA; Deficit irrigation; Evapotranspiration; Gene expression; Leaf water potential; Partial rootzone drying