Transformation Of TvNHX1 Gene Into Soybean And Analysis Of Salt Tolerance In Soybean

Salt stress is an environmental factor that impairs plant growth and productivity severely. Improving the salt tolerance of plants has been a hot field. Soybean (Glycine max L.) is classified as a salt-sensitive glycophyte. Soybean is widely planted in our country. Salt-tolerance gene could be introduced into soybean by the plant gene technology, breeding of new salt-tolerance soybeans. There have a necessary realistic signification for the development of agriculture in our country.In this study, evaluation of the response to four different varieties of soybean under NaCl stress. Under the unstressed control condition, the MDA content and SOD activity of soybeans in the salt-tolerant variety were significantly higher than those in the salt-sensitive variety. However, MDA content sharply decreased and SOD activity significantly increased in salt-tolerant variety after exposure to salt stresses. Our finding indicates that leaf MDA level and SOD activity could be used as two physiological indices for assessing the salt tolerability of variable soybean varieties. The final commercial yield was affected by the short-term salt stress treatments, but differed in different soybean varieties.PBI121-TvNHX1 plasmids were digested with EcoRI and Hind III and get the 35S: TvNHX1: NosT gene fragment, the TvNHX1 gene (1644bp) was inserted into plasmid pCAMBIA3300. The recombinant plasmid P33-TvNHX1 was checked by colony PCR identification and restriction enzyme digestion, Successful construction of the plant expression vector of TvNHX1 gene.The expression vector containing TvNHX1 gene was transformed into five soybean varieties via pollen-tube pathway. When expanded unifoliate leaves of soybean plant, spread one of soybean leave with 0.03﹪Basta. There were 9 TvNHX1 transgenic confirmed by PCR analyses after direct selection for PPT resistance, one of 22293-1 variety; two of 22021-1 variety; three of 21216-6 variety; one of 22451-1 variety; two of 21066-2 variety. RT-PCR was carried out to confirm the expression of the TvNHX1 gene in transgenic plants.The growth condition of root and shoot of transgenic (TvNHX1) plant are much better than control plant, and the salt tolerances of transgenic (TvNHX1) plants were enhanced when exposed to 300mmol/L NaCl. The results demonstrated that TvNHX1 gene could improve the salt tolerance of soybean effectively, but the salt tolerances of transgenic (pCAMBIA3300) plants were not enhanced, the results demonstrated that pCAMBIA3300 gene is no effect on transformation. It also shows that transformation via Pollen-tube pathway is a feasible gene engineering operation in the field of salt tolerance research.PCR analyses of T₂ plants revealed that we have got 20 transgenic plants from 28 plants. The results indicated that the TvNHX1 genes could be inherited to next generation stably.