A total of 278 polymorphic SSR markers were used to genotype the 178 RILs and 58 SSR markers showed polymorphism in the population. These SSR markers were assigned to 12 linkage groups (Figure 1) with a total length of 1365.73 cM and an average distance between adjacent markers of 23.41 cM. The number of markers on each linkage group ranged from 2 to 9. The order of markers in the constructed linkage map and the soybean common linkage map (GmComposite 2003, http://www.soybase.org) were consistent, except that satt591 and satt471 on linkage group A1 and satt560 and satt534 on the B2 linkage group were inversed (Figure 2).
Figure 1. The genetic map of soybean based on SSR markers. The genetic distances (cM) were shown on the left side and the markers on the right.