title: Role of HKT1 in Thellungiella salsuginea, a model extremophile plant.
abstract: Maintenance of the cytosolic Na(+)/K(+) ratio under saline conditions is crucial for plants. HKT-type Na(+) transporters play a key role in keeping low cytosolic Na(+) concentrations thus retaining a low Na(+)/K(+) ratio, that reduces Na(+) toxicity and causing high salinity stress tolerance. Two HKT-type transporters, AtHKT1 from Arabidopsis and TsHKT1;2 from Thellungiella salsuginea, that share high DNA and protein sequence identities, are distinguished by fundamentally different ion selection and salinity stress behavior. On the level of transcription, TsHKT1;2 is dramatically induced upon salt stress, whereas AtHKT1 is downregulated. TsHKT1;2-RNAi lines show severe potassium deficiency and are also sensitive to high [Na(+)]. We have validated the ability of the TsHKT1;2 protein to act as an efficient K(+) transporter in the presence of high [Na(+)] by expression in yeast cells. K(+) specificity is based on amino acid differences in the pore of the transporter protein relative to AtHKT1.
authors.forename: Akhtar
authors.initials: A
authors.lastname: Ali
authors.forename: Hyeong
authors.initials: H
authors.lastname: Cheol Park
authors.forename: Rashid
authors.initials: R
authors.lastname: Aman
authors.forename: Zahir
authors.initials: Z
authors.lastname: Ali
authors.forename: Dae-Jin
authors.initials: DJ
authors.lastname: Yun
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism; D019607:Brassicaceae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D007477:Ions; D008954:Models, Biological; D010940:Plant Proteins / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000378:metabolism; D034622:RNA Interference / Q000187:drug effects; D055051:Salt-Tolerant Plants / Q000187:drug effects / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects
chemical_list: D029681:Arabidopsis Proteins; D007477:Ions; D010940:Plant Proteins; D012965:Sodium Chloride
keywords: HKT1; Na+/K+ ratio; Thellungiella salsuginea; halophyte; salt stress