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 ΔK, 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
