Construction Of Soybean SSR-AFLP Based Genetic Linkage Map And Mapping Of Resistance To Soybean SCN Interrelated Loci

We integrated 52 AFLP markers to a soybean genetic linkage map comprising of 227 SSR loci that was published by Wan et al.(2005), thus constructed a soybean SSR-AFLP based genetic linkage map, spanning 2512cM of Kosambi map distance across 20 linkage groups with the average distance of 9.0cM between adjacent markers. The total length of new SSR-AFLP map is 32% longer than that of the old one, SSR map, due to the integration of AFLP markers. AFLP markers were mainly integrated at the terminals of linkage groups Dla, E, F, G, and K, respectively. Especially in linkage group G, 19 AFLP loci were added to its terminal so that the length of group G increased from 121.2cM to 259.1cM and the average distance between adjacent markers increased from7.129cM to 7.197cM. Therefore, The joining of AFLP markers increased the density oflinkage groups, and improved the uniformity of markers in the linkage groups A2, B1,C1, C2, H, J, L, N, and O. One AFLP marker added in linkage group A2 filled one gap. Two AFLP markers in linkage group D2 filled the big interval which was more than 40cM (Satt301 and Sattl86). In addition, two AFLP markers in linkage group J filled two gaps. Most SSR markers in new SSR-AFLP linkage map are accordant to those of SSR linkage map constructed by Wan et al. (2005) except for linkage groups M, N, and O. For instance, Satt590, Satt201, and Sattl50 displayed transposition in the linkage group M as well as Satt241 and Satt479 in the linkage group O. Some SSR loci displayedtransposition randomly in the linkage group N.According to the soybean SSR genetic linkage map G of resistance to the soybean SCN constructed by Wan et al.(2005),we re-constructed soybean SSR molecular linkage map G. We analylised the QTL of the soybean SCN resistance by composite interval mapping. And we obtained five quantitative trait loci. They were qSCN-g-1, qSCN-g-2, qSCN-g-3, qSCN-g-4, qSCN-g-5. They located linkage map G. The genetic variance explanation ratio were 4.86%,4.79%,5.36%, 9.58%和 9.45%. The result of qSCN-g-1, qSCN-g-2 ,qSCN-g-3 accorded with the study of Mudge et al.and cregan et al.. In the meantime,the black seed coat morphological marker and the brown hila morphological marker were mapped in the linkage group G. I hope my result can guide molecular marker-assisted breeding and highly cultivate soybean resistant varieties.