Isolation and Functional Analysis of Na+/H+ Antiporter Gene (LcNHX1) from Leymus chinensis

Saline-alkali stress has adverse effects on plant growth. Some plant Na+/H+ antiporters were reported to be important in salt tolerance. However, it needs to be better understood that Na+/H+ antiporters are involved in plant salt-alkali (NaHCO3/Na2CO3) tolerance. In this study, a Na+/H+ antiporter gene LcNHX1 (China patent No.200810050629.1) has been cloned from Leymus chinensis. The LcNHX1 CDS contains 1614 bp that encodes 537 amino acids. Amino acid and nucleotide sequence similarity, protein topology modelling, conserved functional domains in the protein sequence, and subcellular localization classified LcNHX1 as a vacuolar NHX1 homolog. Transcription analysis by quantitative RT-PCR indicated that upregulated expression of LcNHX1 could be induced by NaCl, NaHCO3, NaCl + NaHCO3, and PGE in L. chinensis seedlings. The expression of LcNHX1 partially complements the salt-sensitive phenotypes of a Delta nhx1 yeast strain. In addition, LcNHX1 overexpressing enhanced the tolerance to NaHCO3 stress in the transgenic Arabidopsis. Taken together, these results indicated that LcNHX1 is a potential candidate gene for enhancing plant saline-alkali tolerance.