Mapping Of Salt Tolerance Gene And Marker Assisted Selection Analysis Of Soybean Germplasm

Salinization of soil is a severe problem that has negative effects on farm production and ecological environment. It is an efficient measure to improving the utility of the salinity soil by selecting and cultivating salt tolerant varieties. In China there are abundant soybean germplasm, but the phenotype identification of salt tolerance in soybean was difficult, which limited the selection and utilization of salt tolerance resources. Identifying the molecular marker which closely linked with salt tolerance gene in soybean, and then using those molecular markers to identify the marker assisted of germplasm, which is an effective approach to improve identification efficiency of salt tolerance resources and accelerate variety selection of salt tolerance.The purpose of this study was to convert a previously identified RAPD marker into SCAR marker, and map the salt tolerance gene by using different type markers. These markers were used to screen the salt tolerant and sensitive germplasm. The selection efficiency of different type markers in salt tolerant soybean germplasm was analyzed. These would supply some theoretic basic for utility salt tolerant germplasm. Several crosses were made by salt tolerant and salt sensitive material, and molecular markers were used to identify verily hybrids, which would supply material guarantee for the following fine mapping of salt tolerance gene.1. Development and genetic mapping of a SCAR markerThe salt tolerance gene RAPD marker was converted to SCAR marker and was mapped in linkage group N. The salt tolerance gene was mapped between SSR marker Sat₂85 and Satt255. Of all the markers used in this research SCAR marker JD33-432 is the nearest marker linked to the tolerance gene (genetic distance is 2.0 cM).2. Marker assisted selection efficiency of STS, SCAR and CAPS markersSeven new markers were exploited, including 4 STS markers, 2 SCAR markers and one CAPs marker. Five markers which were Linkage disequilibrium with salt tolerance were gained by using LD and characters of salt tolerance germplasm analysis. Using the five markers to detect 145 materials assisted selection efficiency more than 80%. The CAPs marker QS08068 has the greatest efficiency (87.1%).3. Genetic diversity analysis of soybean germplasm by using SSR diversity linked to salt tolerance geneUsing SSR markers which were in the section of salt tolerance gene to determine 145 germplasm, including 55 salt tolerant and 90 salt sensitive materials, from China and USA were used marker analysis. In 145 soybean germplasm, 106 alleles were detected, with 11-27 alleles in different locus. Sixteen and 26 specific alleles were detected in salt tolerant and sensitive germplasm, respectively. SSR marker clustering was not detach the salt tolerance and salt sensitive germplasm, but got 5 relative independence groups, including two salt tolerant groups and three salt sensitive groups.4. The confection of cross combination and identification of real hybrids Eleven crossed were made by salt tolerant and salt sensitive germplasm. Three SSR markers, with polymorphism between every pair of parents and 3 markers which were Linkage disequilibrium with salt tolerance, were used to screen F₁ plants. 81.3% of 148 F₁ plants were real hybrids. By using anyone of the 6 markers, we got a same result showed by all markers, which indicated that a single polymorphic marker is sufficient to test seed purity of the hybrids. This experiment provided efficient segregant population for fine mapping of the salt tolerance gene.