title: Characterization of ion contents and metabolic responses to salt stress of different Arabidopsis AtHKT1;1 genotypes and their parental strains.
abstract: Plants employ several strategies to maintain cellular ion homeostasis under salinity stress, including mediating ion fluxes by transmembrane transport proteins and adjusting osmotic pressure by accumulating osmolytes. The HKT (high-affinity potassium transporter) gene family comprises Na(+) and Na(+)/K(+) transporters in diverse plant species, with HKT1;1 as the only member in Arabidopsis thaliana. Cell-type-specific overexpression of AtHKT1;1 has been shown to prevent shoot Na(+) overaccumulation under salinity stress. Here, we analyzed a broad range of metabolites and elements in shoots and roots of different AtHKT1;1 genotypes and their parental strains before and after salinity stress, revealing a reciprocal relationship of metabolite differences between an AtHKT1;1 knockout line (hkt1;1) and the AtHKT1;1 overexpressing lines (E2586 UAS GAL4 :HKT1;1 and J2731*UAS GAL4 :HKT1;1). Although levels of root sugars were increased after salt stress in both AtHKT1;1 overexpressing lines, E2586 UAS GAL4 :HKT1;1 showed higher accumulation of the osmoprotectants trehalose, gentiobiose, and melibiose, whereas J2731*UAS GAL4 :HKT1;1 showed higher levels of sucrose and raffinose, compared with their parental lines, respectively. In contrast, the knockout line hkt1;1 showed strong increases in the levels of the tricarboxylic acid (TCA) cycle intermediates in the shoots after salt treatment. This coincided with a significant depletion of sugars, suggesting that there is an increased rate of carbon influx into the TCA cycle at a constant rate of C-efflux from the cycle, which might be needed to support plant survival during salt stress. Using correlation analysis, we identified associations between the Na(+) content and several sugars, suggesting that regulation of sugar metabolism is important in plant responses to salinity stress.
authors.affiliation: Australian Centre for Plant Functional Genomics, School of Botany, University of Melbourne, Victoria 3010, Australia.
authors.forename: Camilla B
authors.initials: CB
authors.lastname: Hill
authors.forename: Deepa
authors.initials: D
authors.lastname: Jha
authors.forename: Antony
authors.initials: A
authors.lastname: Bacic
authors.forename: Mark
authors.initials: M
authors.lastname: Tester
authors.forename: Ute
authors.initials: U
authors.lastname: Roessner
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D055786:Gene Knockout Techniques; D005838:Genotype; D018517:Plant Roots / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D013045:Species Specificity; D013312:Stress, Physiological / Q000187:drug effects*; D027981:Symporters / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D052584:Xylem / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; C490286:HKT1 protein, Arabidopsis; D027981:Symporters; D012965:Sodium Chloride