Analysis On Physiological Mechanism Of Salt Tolerance And Cloning Of Salt Tolerant-Associated Gene TaNHX3 In Wheat

Soil salinization is one of biotic environments affecting agriculture yield around the world. In past several years, salinity scale and secondary salinization of the arable land have been increased year and year, resulting in the restriction of the cropproduction in China. Wheat is acted as one of important crops, the production level affects the living life. Therefore, increasing crops to resist salt stress has an important potential for improving plant growth, development and yield. Breeding salt tolerance varieties is adopted a significant approach for increasing the production in wheat. Determination of the salt tolerance abilities across the different wheat varieties at the same time revealed that the morphological and physiological indices could be used as important practical meanings for distinguishing salt tolerance varieties and breeding salt tolerance varieties. In this study, 15 wheat varieties were used as the experimental materials to investigate the salt's influence on germination percentage, germination index, vigor index, length of sprouts and roots, root number by germinating test, and to determine and analyse the morphological and physiological indicates at the seedling in the salt intimidation, to ascertain the high salt tolerance varieties and salt sensitivity varieties. Using modern biology informatics and molecule biology technology, the molecular characterization of TaNHX3 , has been analyzed through transgene analysis. The main results were as follows:1. In germination test, germination percentage, germination index, vigor index, length of sprouts and roots of all cultivar were limited by salt, some indices's between fore-treatment and aft-treatment were measued.2. Salt stress treatment infected the physiological indices of seedling, the indices including dry matter weight, plant height, leaf area, chlorophyll content, soluble protein content, superoxide dismutase activities and malondialdehyde content. Along with salt stress treatment time extendent, the salt harm degrees of seedling were increasing. Except MDA content, subjection values of salt toxicity coefficient of the rest indices and the sum subjection values had the most marked differentances.3. Molecule character analysis indicated the cDNA ORF of TaNHX3 is 1641 bp, encoding 546 aa with a molecular weight 59.47 kDa and a isoelectric point 8.15. Phylogenetic analysis suggested that TaNHX3 had higher similarities with TaNHX1, LeNHX3, and TeNHX3.4. In different salt tolerance of wheat varieties and different apparatus of one wheat variety, TaNHX3's expression levels were different. Whether leaf or root, TaNHX3's expression time was earlier in high salt tolerance variety J 7369 than salt sensitivity variety ShiMai 12, and in the same variety, the expression time was earlier in root than leaf.5. Using the DNA recombinant technique, the binary expression vector that fused TaNHX3 the open reading frame has been constructed. After salt stress, The transgenic plants of TaNHX3 which had high expression level of the target gene also had higher chlorophyll contents and soluble protein content than the control, MDA content was lower than the control. These results indicated that high expression of TaNHX3 could reduce the harm of plant.6. Using basal portion of wheat seedlings as explants for wheat inherit transformation, received the plants transformed empty binary vector pCAMBIA3301 of J 7369 and ShiMai 12. PCR and GUS dye indicated this plamid was integrated into wheat, and express. This technology can be used to inherit transformation of wheat in the future.