Culitvation Of Transgenic Soybean Plants With SsNHX1Gene And Its Salt Tolerance

Soil salinization presents an increasing threat to soybean yield and quality in Northeastarea of China. The conventional breeding to select new cultivar is time-consuming andlaborious. Genetically modified plant has been widely used to improve salt tolerance ofsoybean due to the characteristic of short growth period and controllability of transgenicoffspring.SsNHX1is originally derived from Suaeda and encodes the tonoplast Na~+/H+antiporterwhich is mainly responsible for segmenting Na~+into vacuole, the content of Na~+in cytoplasmthereby can be reduced. The tonoplast Na~+/H+antiporter can endow plants with salt tolerance.Currently the gene has been successfully transformed into Arabidopsis, Rice, Alfalfa Clover,etc. According to relevant study results salt tolerance of the transgenic plants wassignificantly increased.In this study the constructed vector of pBI-SsNHX1has been transformed into soybean(Jilin35) by infecting embryo tip mediated by A.tumefaciens. By grafting transgenic soybeanscion onto non-transgenic stock,54plants were obtained, and8of them were identifiedpositive transgenic progeny, which means transformation efficiency increased to14.8%.Relative physiological experiments were conducted on progeny of transgenic soybeans (T2).The experimental materials were treated with different salt concentration ranging from0mMto240mM. The transgenic line N-5was selected to conduct salt-resistant test. Theexperimental results indicated when treated under concentration of240mM for12days,transgenic plants leaves began blighting, meanwhile concentration of Na~+, photosynthetic rateand proline amount are1.26,1.76and1.44times higher respectively than that of controlgroup, while membrane integrity was only0.54times as high as control. In addition, under180mM, soluble sugar content of the transgenic plant’s leaves was1.57times higher. Theseresults illustrated that salt tolerance for soybean can be effectively improved byoverexpression of SsNHX1gene.In conclusion, this study identified that SsNHX1was an excellent gene for breedingsalinity soybean cultivar. The transgenic materials obtained from our experiments will becarried out propagation and screening. We look forward to obtain steadily heritable SsNHX1transgenic soybean lines in order to provide new material for breeding salinity soybean lines.