For clarifying the hierarchical patterns of population structure of soybean landraces in China, the seven clusters previously identified using Bayesian clustering of 1 504 soybean landraces based on SSR markers genotyping data were further analyzed. Using the largest value of AK, these landraces could be split into 20 sub-clusters, which was supported by highly significant pairwise Fst-values and generally in accordance with the geographic origin and sowing types. The autumn-sowing types ended up in one distinct sub-cluster from the otherwise summer-sowing type, where the autumn- sowing types are most likely derived from. The division into 20 sub-clusters explained 7.3% of the genetic variation, next to 9.7% present among the seven clusters, 81.1% residing among landraces within sub-clusters, and 1.9% within the landraces. The distribution pattern of genetic diversity among the sub-clusters of each cluster was uneven, with two HSuM sub-clusters （Central China） and some South China sub-clusters showing significantly higher level of genetic diversity.
LI Ying-huiMarinus J M SmuldersCHANG Ru-zhenQIU Li-juan
Developing expressed sequence tag-derived SSR （EST-SSR） markers is imperative in genetic research. In this paper, we reported 37 EST-SSR markers which were developed from 286 unigenes obtained from soybean cDNA library. Among the 286 markers designed for the 4 accessions of Glycine max and 6 of its wild progenitor （G. soja） within the subgenus Soja, 209 markers amplified DNA fragments, taking 73.1% and 37 markers appeared to be polymorphic, which was 12.9% of the total. The 37 loci detected a total of 142 alleles, while the PIC values varied from 0.194 to 0.794. Both the number of alleles per locus and PIC value were significantly related to the SSR motif. Six EST-SSR loci may be fixed for different alleles between G. max and G. soja since they were particularly polymorphic among the 6 G. soja accessions. A neighbor-joining tree placed the G. max accessions together as a group within the G. soja, though the average genetic distance among G. soja accessions was much higher. These new EST-SSRs markers will be useful for genetic diversity analysis, genetic mapping construction and gene discovery in Soja subgenus.
LIU Yu-linLI Ying-huiZHOU Guo-anUzokwe NCHANG Ru-zhenCHEN Shou-yiQIU Li-juan
