Construction Of AtNHX 1 Gene Binary Vector And Agrobacterium-mediated Transformation Of Medicago Sativa L

High salinity is one of the major abiotic stresses which constraints crop plant growth, development and productivity in many places. Improving the salt tolerance of plants has been an important project. Past efforts through traditional breeding and genetic engineering have had limited success owing to the genetic complexity of stress responses. With the development of molecular biology and transgenic, the discovery of salt resistance related novel genes, determination of their expression patterns and improved understanding of their roles, have paved the way for new transgenic strategies. By manipulating salt tolerance related genes in plants, many transgenic plants with enhanced salt tolerant have been obtained. Now, transferring AtNHXI gene wheat and maize have been reported, in which salt tolerant capability enhanced obviously. This raised the glory perspective to obtain salt resistance plants.As an important legume forage plant, Medicago sativa L is planted widely in our country. Therefore, to enhance salt tolerance of Medicago sativa L by transgenic technology producing a new stress-resistance, have a necessary realistic signification for the development of legume forage crops in our country.In this study, expression cassettes including a CaMV35S promoter, At NHX I gene and NOS poly A sequence were cloned into the T-DNA region of the binary vector pCAMBIA1300, and the vector was transformed into Agrobacterium tumefaciens LBA4404 by freeze-thaw method, which would be used to transform into plants. Regeneration system and transformation conditions of Medicago sativa L were optimized. Transferred by Agrobacterium tumefaciens LBA4404, some Hygromycin-B phosphotransferase-resistant calli were obtained. Integration and transcription on RNA level of HTP gene and AtNHX I gene in transgenic calli were comfirmed by PCR and RT-PCR. The examination of resistance to NaCl of transgenic calli demonstrated that under the different NaCl concentration, the growth states and relative growth rate of the transgenic calli were better than that of un-transformed calli. Therefore, transgenic calli with AtNHXI gene enhanced salt tolerance.