title: The wheat NHX antiporter gene TaNHX2 confers salt tolerance in transgenic alfalfa by increasing the retention capacity of intracellular potassium.
abstract: Previous studies have shown that TaNHX2 transgenic alfalfa (Medicago sativa L.) accumulated more K(+) and less Na(+) in leaves than did the wild-type plants. To investigate whether the increased K(+) accumulation in transgenic plants is attributed to TaNHX2 gene expression and whether the compartmentalization of Na(+) into vacuoles or the intracellular compartmentalization of potassium is the critical mechanism for TaNHX2-dependent salt tolerance in transgenic alfalfa, aerated hydroponic culture was performed under three different stress conditions: control condition (0.1 mM Na(+) and 6 mM K(+) inside culture solution), K(+)-sufficient salt stress (100 mM NaCl and 6 mM K(+)) and K(+)-insufficient salt stress (100 mM NaCl and 0.1 mM K(+)). The transgenic alfalfa plants had lower K(+) efflux through specific K(+) channels and higher K(+) absorption through high-affinity K(+) transporters than did the wild-type plants. Therefore, the transgenic plants had greater K(+) contents and [K(+)]/[Na(+)] ratios in leaf tissue and cell sap. The intracellular compartmentalization of potassium is critical for TaNHX2-induced salt tolerance in transgenic alfalfa.
authors.affiliation: Institute of Genetics and Physiology, Hebei Academy of Agriculture and Forestry Sciences, Plant Genetic Engineering Center of Hebei Province, Shijiazhuang, 050051, China, zhym63@sohu.com.
authors.forename: Yan-Min
authors.initials: YM
authors.lastname: Zhang
authors.forename: Hong-Mei
authors.initials: HM
authors.lastname: Zhang
authors.forename: Zi-Hui
authors.initials: ZH
authors.lastname: Liu
authors.forename: Hui-Cong
authors.initials: HC
authors.lastname: Li
authors.forename: Xiu-Lin
authors.initials: XL
authors.lastname: Guo
authors.forename: Guo-Liang
authors.initials: GL
authors.lastname: Li
mesh_terms: D017343:Genes, Plant; D000455:Medicago sativa / Q000235:genetics* / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D055049:Salt Tolerance / Q000235:genetics* / Q000502:physiology; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics* / Q000378:metabolism*; D014908:Triticum / Q000235:genetics* / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D017923:Sodium-Hydrogen Exchangers; D011188:Potassium