Improving Salt-tolerance Of Potato By The AtNHX1 Gene Of Vacuolar Na～+/H～+ Antiport Of Arabidopsis Thaliana

Soil salinization is one of the major factors compromising crop growth and leading to soil degeneration and desertification in natural ecological environment. Because most of the food crops are glycophytes of high susceptibility or low tolerance to high soil salinity, they are incapable of performing normal growth and production and would die in the salty soil. Therefore development of new salt-tolerant crop varieties capable of growing in the salt soil or modified salt soil is critical to utilize the vast salty soils.Through improving our understanding of the mechanism of salt tolerance in plants, especially the establishments of technologies for gene isolation and identification and for gene manipulation and genetic engineering relevant to salt tolerance, new methodologies have been developed for breeding new crop varieties with strong salt tolerance. This was not possible to achieve through traditional breeding. Such new varieties have already been playing an important role in better utilizing the salt soils.Adaptation of plant to salt stress requires improved cellular ion homeostasis involving organic solute accumulation in cytosol, vacuolar compartmentalization of ion and exclusion of extra Na~+ ion from cells, of which the compartmentalization of Na~+ into vacuoles and the exclusion of extra Na~+ from the cells are implemented by Na~+/H~+ antiporter located in both plasma membrane and tonoplast. In particular, the compartmentalization of Na~+ can help absorption and reservation of the ions into the vacuoles which would then demonstrate an improved osmotic adjustment. The volume of vacuoles in matured cells of higher plants makes up 95% of the total cell volume, therefore the compartmentalization of Na~+ is fundamental and plays a more important role than the organic solute accumulation in improving the salt tolerance of plant to survive the salt stress.The aims of the study were: (1) to isolate the tonoplast Na~+/H~+ antiporter gene (AtNHXl) from Arabidopsis thaliana using RT-PCR and to reconstruct expression vectors of the AtNHXl gene under the control of different promoters through fusing it with constitutive promoter CaMV35S or inducible promoter rd29A; (2) to verify the function of the AtNHXl gene driven by the constitutive promoter CaMV35S and transferred into onion epidermal cells and tobacco plants induced by Agrobacterium tumefaciens; and (3) to improve and evaluate the salt tolerance of transgenic...