title: ABA accumulation in water-stressed Citrus roots does not rely on carotenoid content in this organ.
abstract: Sustained abscisic acid (ABA) accumulation in dehydrated citrus roots depends on the transport from aerial organs. Under this condition, the role of the β,β-carotenoids (ABA precursors) to the de novo synthesis of ABA in roots needs to be clarified since their low availability in this organ restricts its accumulation. To accomplish that, detached citrus roots were exposed to light (to increase their carotenoid content) and subsequently dehydrated (to trigger ABA accumulation). Stress imposition sharply decreased the pool of β,β-carotenoids but, unexpectedly, no concomitant rise in ABA content was observed. Contrastingly, roots of intact plants (with low levels of carotenoids) showed a similar decrease of ABA precursor together with a significant ABA accumulation. Furthermore, upon dehydration both types of roots showed similar upregulation of the key genes involved in biosynthesis of carotenoids and ABA (CsPSY3a; CsβCHX1; CsβCHX2; CsNCED1; CsNCED2), demonstrating a conserved transcriptional response triggered by water stress. Thus, the sharp decrease in root carotenoid levels in response to dehydration should be related to other stress-related signals instead of contributing to ABA biosynthesis. In summary, ABA accumulation in dehydrated-citrus roots largely relies on the presence of the aerial organs and it is independent of the amount of available root β,β-carotenoids.
authors.affiliation: Ecofisiología y Biotecnología, Dept. Ciències Agraries i del Medi Natural, Universitat Jaume I, E-12071 Castellón de la Plana, Spain.
authors.forename: Matías
authors.initials: M
authors.lastname: Manzi
authors.affiliation: Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Avenida Agustín Escardino 7, 46980 Valencia, Spain.
authors.forename: Joanna
authors.initials: J
authors.lastname: Lado
authors.affiliation: Instituto de Agroquímica y Tecnología de Alimentos (IATA), Consejo Superior de Investigaciones Científicas (CSIC), Avenida Agustín Escardino 7, 46980 Valencia, Spain.
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Rodrigo
authors.affiliation: Ecofisiología y Biotecnología, Dept. Ciències Agraries i del Medi Natural, Universitat Jaume I, E-12071 Castellón de la Plana, Spain.
authors.forename: Vicent
authors.initials: V
authors.lastname: Arbona
authors.affiliation: Ecofisiología y Biotecnología, Dept. Ciències Agraries i del Medi Natural, Universitat Jaume I, E-12071 Castellón de la Plana, Spain. Electronic address: aurelio.gomez@uji.es.
authors.forename: Aurelio
authors.initials: A
authors.lastname: Gómez-Cadenas
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D001692:Biological Transport; D002338:Carotenoids / Q000378:metabolism*; D002957:Citrus / Q000378:metabolism* / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D009997:Osmotic Pressure; D018517:Plant Roots / Q000378:metabolism / Q000502:physiology; D013312:Stress, Physiological; D015854:Up-Regulation; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water; D002338:Carotenoids; D000040:Abscisic Acid
keywords: 9-cis-Epoxycarotenoid dioxygenase (NCED); Gene expression; Jasmonoyl-isoleucine (JA-Ile); Osmotic stress; Shoot-to-root transport; Water deficit