Abstract：The tonoplast Na+/H+ antiporter gene (AtNHX1) of Arabidopsis thaliana playes important roles on saline tolerance of the plant. In order to identify of (AtNHX1) gene function and create new germplasm of tobacco, the AtNHX1 gene under the control of stress-induced rd29A promoter was transferred into tobacco (Nicotiana tabacum L.) tissues by Agrobacterium-mediated transformation. A total of 72 regenerated plants resisted to Kanamycin were obtained, of which 17 grew well in MS medium supplemented with 85.5 mmol/L NaCl. Subsequent PCR, Southern and Northern hybridizations validated the genomic insertion and normal expression of the AtNHX1 gene in the transgenic tobacco plants. The up-regulated expression of AtNHX1 gene was induced by salt challenge. The growth and root development of the transgenic plants were significantly better than that of the controls in the mediums supplemented with 171, 256 and 342 mmol/L of NaCl while the concentration of malonyldialdehyde in the leaves of transgenic plants was significantly lower than that in the controls. The results indicated that the insertion and expression of AtNHX1 gene controlled by rd29A promoter could significantly enhance the salt tolerance of transgenic tobacco plants. These results revealed that the AtNHX1 gene regulated by rd29A promoter could be normally expressed in heterologous plant and its expression could improve the saline tolerance of the receipt plant. Therefore, genetic transformation of the AtNHX1 gene can be one of gene-engineering strategies for breeding saline tolerant crop.
