title: SbHKT1;4, a member of the high-affinity potassium transporter gene family from Sorghum bicolor, functions to maintain optimal Na⁺ /K⁺ balance under Na⁺ stress.
abstract: In halophytic plants, the high-affinity potassium transporter HKT gene family can selectively uptake K⁺ in the presence of toxic concentrations of Na⁺. This has so far not been well examined in glycophytic crops. Here, we report the characterization of SbHKT1;4, a member of the HKT gene family from Sorghum bicolor. Upon Na⁺ stress, SbHKT1;4 expression was more strongly upregulated in salt-tolerant sorghum accession, correlating with a better balanced Na⁺ /K⁺ ratio and enhanced plant growth. Heterogeneous expression analyses in mutants of Saccharomyces cerevisiae and Arabidopsis thaliana indicated that overexpressing SbHKT1;4 resulted in hypersensitivity to Na⁺ stress, and such hypersensitivity could be alleviated with the supply of elevated levels of K⁺, implicating that SbHKT1;4 may mediate K⁺ uptake in the presence of excessive Na⁺. Further electrophysiological evidence demonstrated that SbHKT1;4 could transport Na⁺ and K⁺ when expressed in Xenopus laevis oocytes. The relevance of the finding that SbHKT1;4 functions to maintain optimal Na⁺ /K⁺ balance under Na⁺ stress to the breeding of salt-tolerant glycophytic crops is discussed.
authors: Key Laboratory of Plant Resources, Institute of Botany, the Chinese Academy of Sciences, Beijing, 100093, China.
authors: Tian-Tian
authors: TT
authors: Wang
authors: Zhi-Jie
authors: ZJ
authors: Ren
authors: Zhi-Quan
authors: ZQ
authors: Liu
authors: Xue
authors: X
authors: Feng
authors: Rui-Qi
authors: RQ
authors: Guo
authors: Bao-Guo
authors: BG
authors: Li
authors: Le-Gong
authors: LG
authors: Li
authors: Hai-Chun
authors: HC
authors: Jing
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D027682:Cation Transport Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D005816:Genetic Complementation Test; D015640:Ion Channel Gating / Q000187:drug effects; D007700:Kinetics; D008969:Molecular Sequence Data; D005810:Multigene Family; D009154:Mutation / Q000235:genetics; D009865:Oocytes / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism; D054712:Salinity; D055051:Salt-Tolerant Plants / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D012964:Sodium / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology; D045868:Sorghum / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics*; D027981:Symporters / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D013997:Time Factors; D014981:Xenopus
chemical_list: D027682:Cation Transport Proteins; C088864:HKT1 protein, plant; D010940:Plant Proteins; D027981:Symporters; D012965:Sodium Chloride; D012964:Sodium; D011188:Potassium
keywords: High-affinity potassium transporter (HKT); Na+ stress; Na+/K+ ratio; Sorghum bicolor; salt tolerance