title: Chloride regulates leaf cell size and water relations in tobacco plants.
abstract: Chloride (Cl(-)) is a micronutrient that accumulates to macronutrient levels since it is normally available in nature and actively taken up by higher plants. Besides a role as an unspecific cell osmoticum, no clear biological roles have been explicitly associated with Cl(-) when accumulated to macronutrient concentrations. To address this question, the glycophyte tobacco (Nicotiana tabacum L. var. Habana) has been treated with a basal nutrient solution supplemented with one of three salt combinations containing the same cationic balance: Cl(-)-based (CL), nitrate-based (N), and sulphate+phosphate-based (SP) treatments. Under non-saline conditions (up to 5 mM Cl(-)) and no water limitation, Cl(-) specifically stimulated higher leaf cell size and led to a moderate increase of plant fresh and dry biomass mainly due to higher shoot expansion. When applied in the 1-5 mM range, Cl(-) played specific roles in regulating leaf osmotic potential and turgor, allowing plants to improve leaf water balance parameters. In addition, Cl(-) also altered water relations at the whole-plant level through reduction of plant transpiration. This was a consequence of a lower stomatal conductance, which resulted in lower water loss and greater photosynthetic and integrated water-use efficiency. In contrast to Cl(-), these effects were not observed for essential anionic macronutrients such as nitrate, sulphate, and phosphate. We propose that the abundant uptake and accumulation of Cl(-) responds to adaptive functions improving water homeostasis in higher plants.
authors.affiliation: Instituto de Recursos Naturales y Agrobiología, CSIC, Avda Reina Mercedes 10, 41012-Sevilla, Spain.
authors.forename: Juan D
authors.initials: JD
authors.lastname: Franco-Navarro
authors.affiliation: Instituto Valenciano de Investigaciones Agrarias, Centro de Genómica, Ctra Moncada-Náquera Km 4.6, 46113-Moncada, Valencia, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Brumós
authors.affiliation: Instituto de Recursos Naturales y Agrobiología, CSIC, Avda Reina Mercedes 10, 41012-Sevilla, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Rosales
authors.affiliation: Instituto de Recursos Naturales y Agrobiología, CSIC, Avda Reina Mercedes 10, 41012-Sevilla, Spain.
authors.forename: Paloma
authors.initials: P
authors.lastname: Cubero-Font
authors.affiliation: Instituto Valenciano de Investigaciones Agrarias, Centro de Genómica, Ctra Moncada-Náquera Km 4.6, 46113-Moncada, Valencia, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Talón
authors.affiliation: Instituto de Recursos Naturales y Agrobiología, CSIC, Avda Reina Mercedes 10, 41012-Sevilla, Spain chemacf@irnase.csic.es.
authors.forename: José M
authors.identifier: http://orcid.org/0000-0001-9475-1187
authors.initials: JM
authors.lastname: Colmenero-Flores
mesh_terms: D000838:Anions; D002412:Cations; D048429:Cell Size / Q000187:drug effects*; D002712:Chlorides / Q000494:pharmacology*; D009995:Osmosis / Q000187:drug effects; D010710:Phosphates / Q000494:pharmacology; D018515:Plant Leaves / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development; D054046:Plant Stomata / Q000187:drug effects / Q000502:physiology; D013431:Sulfates / Q000494:pharmacology; D014026:Nicotiana / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D014867:Water / Q000378:metabolism*
chemical_list: D000838:Anions; D002412:Cations; D002712:Chlorides; D010710:Phosphates; D013431:Sulfates; D014867:Water
keywords: Beneficial nutrient; WUE.; chloride nutrition; growth; osmotic potential; turgor; water balance; water potential; water relations; water-use efficiency