Inheritance And Gene Mapping Of Resistance To Soybean Mosaic Virus Strain SC10 In Soybean

Soybean mosaic disease, caused by soybean mosaic virus (SMV), is one of diseases in soybean production worldwide. It causes yield loss and seed quality deficiency seriously. That breeding resistant varieties is the most efficient method to control the damage. Many studies on inheritance and molecular markers of resistance genes to SMV strains have been conducted in soybean.The major objectives of present study were to study the inheritance of resistance to strain SC10 and to identify the microsatellite markers linking to the resistance gene in order to provide some useful information for soybean breeding for disease resistance and to make preparations for the fine mapping and map-based cloning of resistant gene. The main results were as follows:1. After 26 soybean varieties were inoculated with SC4,SC8 and SC10, we found .Kefeng No.1, Jinda74 and Dabaima et al were resistant (R) and Nannong1138-2,Dongda No.2 and 8101 et al were susceptible(S) to the three SMV strains.2. Six resistance cultivars to SMV strain SC10,KefengNo.1, Jinda74, Dabaima, Fendou56, Zhongzuo229 and XudouNo.1 was crossed respectively with a susceptible (S) cultivar (Nannong1138-2 or 8101) to determine the inheritance of their resistance(R) reaction to SC10. R parents were also crossed with the other R parents to test the allelism of the resistance genes. The results showed that a dominant gene controlled the resistance to SC10 in Kefeng No.1, Jinda74, Dabaima, Fendou56, Zhongzuo229 and XudouNo.1 respectively. The absence of S segregation in F2 populations of the crosses from Jinda74×Fendou56 and XudouNo.1×Pixianchadou indicated that the resistance genes in them were at a common locus or very closely linked. Segregation in the F2 populations from KefengNo.1×Kwanggyo, Fendou56, Zhongzuo229; Jinda74×Zhongzuo229, Kwanggyo, DabaimaxFendou56, Kefeng No.1 and Yuejin No.4×Kwanggyo were fitted to a ratio of 15R:1S. It was inferred that the resistance genes between Kefeng No.1 and Kwanggyo,Fendou56,Zhongzuo229, between Jinda74 and Zhongzuo229,Kwanggyo; between Dabaima and Fendou56, Kefeng No.1; between Yuejin No.4 and Kwanggyo were not at same locus.3. The bulked segregant analysis (BAS) of SSR markers was conducted to map the resistance genes. In F2 of Kefeng No.1×Nannong1138-2, seven SSR markers Satt634,Satt558,Sat₂54,gm020546, gm020562, gm020580 and gm020584 was found linked to Rscio with genetic distance of 6.1cM,2.0cM,0.9cM,9.2cM,4.6cM,0.8cM and 2.0 cM. Rscio was located in Dlb linkage group of soybean.4. To understand selection efficiency of SSR markers,176 soybean germplasms which have been identified by inoculation with SC13 were evaluated by SSR markers Satt558 and Sat₂54. The results showes that selection efficiency of Satt558 and Sat₂54 was 51.5% and 59.1% respectively. The selection efficiency can reach 65.4% when two SSR markers.were co-used.