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Isolation and characterization of a tonoplast Na+/H+ antiporter from the halophyte Nitraria sibirica

Wang, L., Ma, Y. K., Li, N. N., Zhang, W. B., Mao, H. P., Lin, X. F.
Biologia plantarum 2016 v.60 no.1 pp. 113-122
Arabidopsis, Nitraria, abscisic acid, amino acids, cold, complementary DNA, gene overexpression, genes, halophytes, open reading frames, promoter regions, protons, rapid amplification of cDNA ends, reverse transcriptase polymerase chain reaction, reverse transcription, salt stress, salt tolerance, sequence homology, sodium, sodium chloride, sodium-hydrogen antiporter, tonoplast, transgenic plants
Na⁺/H⁺ exchanger (NHX)-mediated Na⁺ and H⁺ antiport is an important mechanism for salt tolerance in plants. In this study, an Na⁺/H⁺ antiporter gene, referred to as NsNHX1, was isolated from the halophyte Nitraria sibirica Pall. using degenerate polymerase chain reaction (PCR) and rapid amplification of cDNA ends (RACE). The resulting 2 182 bp NsNHX1 cDNA contained a 1 635 bp open reading frame (ORF) that encoded 544 amino acids and showed striking sequence similarity to tonoplast-localized NHXs from other plants. Subcellular localization analysis confirmed NsNHX1 to be a tonoplast-localized protein. Cis-elements described as being responsive to biotic and abiotic stresses were present in the NsNHX1 promoter region, and reverse transcription (RT)-PCR analysis confirmed that NsNHX1 expression was induced by exogenous abscisic acid (ABA), cold, and NaCl. Transcription of NsNHX1 increased sharply 3 h after treatment with 200 mM NaCl revealing that NsNHX1 responded rapidly to the salt stress. Overexpression of NsNHX1 enhanced salt tolerance in transgenic Arabidopsis thalliana L. suggesting that NsNHX1-mediated Na⁺ compartmentalization played an important role in enhancing plant salt tolerance.