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Scientia Silvae Sinicae ›› 2014, Vol. 50 ›› Issue (3): 38-44.doi: 10.11707/j.1001-7488.20140306

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Isolation and Expression Analysis of a Vacuolar Membrane Na+/H+ Antiporter Gene NtNHX1 from Nitraria tangutorum

Tang Xin1,2,3, Wang Ruihui1, Yang Xiuyan2,3, Zhu Jianfeng2,3, Liu Zhengxiang2,3, Ni Jianwei2,3, Zhang Huaxing2,3   

  1. 1. Central South Forestry University of Science and Technology Changsha 410004;
    2. Research Center of Saline and Alkali Land of State Forestry Administration Beijing 100091;
    3. State Key Labortory of Tree Genetics and Breeding Beijing 100091
  • Received:2013-11-14 Revised:2013-12-31 Online:2014-03-25 Published:2014-04-16
  • Contact: 张华新

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Abstract:

The plant Na+/H+ antiporter (NHX) can regionalize the excess Na+ of cytoplasm in the vacuole. This process can avoid the noxious effects of Na+ in the cytosol and maintain osmotic balance by using Na+ amassed in the vacuole to drive water into the cell, thus facilitating the plants to resist salt stress. In this work, a full-length cDNA sequence of NtNHX1 gene was obtained from leaves of Nitraria tangutorum using RT-PCR and RACE, named NtNHX1(GenBank accession number KF751928). Sequence analysis indicated that NtNHX1 is 2 184 bp in full length, containing a 5'-untranslated region (5'-UTR) of 281 bp, a 3'-UTR of 218 bp and 29 bp of the ploy(A) tail.The NtNHX1 cDNA encodes a protein of 544 amino acids with a pI of 8.14 and a deduced molecular mass of 59.9 kDa. Amino acid sequence alignment with other species showed that the N. tangutorum of NtNHX1 displayed the highest similarity(81%) to citrus. NtNHX1 has twelve putative transmembrane (TM)domain structures, of which the TM3 transmembrane structure includes the conserved amilorude-binding sites (LFFIYLLPPI). The amilorude-binding site was found to be responsible for playing a competitive role. Relative Real-Time PCR analysis indicated that NtNHX1 expressed in root, stems and leaves. The expression in leaves was highest. The transcript level of NtNHX1 in the leaves was obviously increased by 200 mmol·L-1 NaCl treatment, and the expression of NtNHX1 reached to the highest in 12 h of treatment. The study indicated that the expression of NtNHX1 gene was related to the induction and regulation of salt stress.

Key words: Nitraria tangutorum, Na+/H+ antiporter, NtNHX1, gene cloning, expression analysis

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