title: Nitrate-dependent shoot sodium accumulation and osmotic functions of sodium in Arabidopsis under saline conditions.
abstract: Improving crop plants to be productive in saline soils or under irrigation with saline water would be an important technological advance in overcoming the food and freshwater crises that threaten the world population. However, even if the transformation of a glycophyte into a plant that thrives under seawater irrigation was biologically feasible, current knowledge about Na+effects would be insufficient to support this technical advance. Intriguingly, crucial details about Na+uptake and its function in the plant have not yet been well established. We here propose that under saline conditions two nitrate-dependent transport systems in series that take up and load Na+into the xylem constitute the major pathway for the accumulation of Na+in Arabidopsis shoots; this pathway can also function with chloride at high concentrations. In nrt1.1 nitrate transport mutants, plant Na+accumulation was partially defective, which suggests that NRT1.1 either partially mediates or modulates the nitrate-dependent Na+transport. Arabidopsis plants exposed to an osmotic potential of -1.0 MPa (400 mOsm) for 24 h showed high water loss and wilting in sorbitol or Na/MES, where Na+could not be accumulated. In contrast, in NaCl the plants that accumulated Na+lost a low amount of water, and only suffered transitory wilting. We discuss that in Arabidopsis plants exposed to high NaCl concentrations, root Na+uptake and tissue accumulation fulfil the primary function of osmotic adjustment, even if these processes lead to long-term toxicity.
authors.affiliation: Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Campus de Montegancedo, 28223, Pozuelo de Alarcón, Madrid, Spain.
authors.forename: Rocío
authors.initials: R
authors.lastname: Álvarez-Aragón
authors.affiliation: Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Campus de Montegancedo, 28223, Pozuelo de Alarcón, Madrid, Spain.
authors.forename: Alonso
authors.initials: A
authors.lastname: Rodríguez-Navarro
mesh_terms: D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000378:metabolism; D009154:Mutation; D009566:Nitrates / Q000378:metabolism*; D009995:Osmosis; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000378:metabolism*; D054712:Salinity; D012964:Sodium / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism; D052584:Xylem / Q000378:metabolism
chemical_list: D027321:Anion Transport Proteins; D029681:Arabidopsis Proteins; C101492:NRT1.1 protein, Arabidopsis; D009566:Nitrates; D010940:Plant Proteins; C477653:SOS1 protein, Arabidopsis; D017923:Sodium-Hydrogen Exchangers; D012964:Sodium
keywords: Arabidopsis thaliana; Na+ transport; osmotic shock; salinity; water deficit; wilting