Genetic Diversity Analysis Of Salt-tolerant Germplasm In Wheat

Soil saline is a serious problem worldwide and wheat (Triticum aestivum L.) is the major food crop secondary to rice. Therefore, it is of great economic and theoretic importance for the improvement of salt tolerance of wheat to exploit the soil resources of the saline regions and to raise the sowing dimension and yield of the food crops. Therefore, the identification of salt tolerance of the wheat germplasm and the basic research related to salt tolerance have been becoming a hotspot. In this study, a total of 80 accessions of salt-tolerant wheat were screened to identify their salt tolerance at the germination, seedling and adult plant stage in lab and field by the morphology and to estimate genetic diversity by the use of SSR markers. The principal conclusions were summarized as follows:1. The salt threshold for the germination of Chinese Spring (the salt-sensitive cultivars) under the hydroponics condition was 350mM NaCl, and the thresholds for Kharchia and SW12 (the salt-tolerant cultivars) were 425mM NaCl and 450mM NaCl respectively. Thus, 350mM NaCl was selected as the salinity concentration for the identification of salt tolerance at the stage of germination.2. The salt threshold for the seedling of Chinese Spring under hydroponics' condition was 300mM NaCl concentration, and the threshold for SW12 was 400mM NaCl concentration. Thus, 300～400mM NaCl was selected as the salinity concentration for salt tolerance at the stage of seedling.3. The salt tolerance identification at the stage of germination showed that the relatively salt-harmed rates of seven accessions, i. e. PI137733(SW10), PI140187(SW12), PI172549, PI176265, Yecola RoJo, Anza and Kharchia, were less than 20%, indicating that they were highly salt-tolerant. The others were salt-tolerant.4. The salt tolerance identification at the stage of seedling showed that ten accessions, i. e. SWM15389"S", Chadianhong, Jinghe91-7078, Jinghe 91Jian27,Jinghe 91 Jian 28,442M-1, SWRS79, SW10, SW12 and Kharchia, were salt-tolerant. The others were intermediate salt-tolerant.5. The trial in the field showed that the yields per 667m~2 of SW10 and SW12 under 0.3%～0.5% salinity of soil were 273.4kg and 287.1kg respectively, which were 99. 7kg and 113. 4kg more than that of Ningchun 4(CK).6. 32 selected microsatellite markers in wheat were highly polymorphic. A total of 155 alleles were detected among the 80 accessions with salt tolerance. The number of alleles per SSR loci varied from 1 to 12, most of them being varied from 4 to 8. On average 4. 75 alleles per loci were observed.7. The genetic distance among the 80 accessions of salt-tolerant cultivars of wheat varied from 0. 26 to 0.81.8. Cluster analysis among the 80 accessions with salt tolerance showed that all the cultivars were clustered into two groups, and the two groups coincide with the winter wheat group and the spring wheat group.9. Major accessions with same pedigree backgrounds were clustered into one subgroup while minorities were not.10. The difference of in genome A, B and D was small, but the number of alleles in genome B was the most.In addition, the paper discussed the methods of identification for salt tolerance, the concepts related to salt tolerance, and the genetic diversity of the salt-tolerant cultivars of wheat used in the present study.