| The cultivated soybean (Glycine.max) has been thought to originate in China. Its annual species wild soybean (G. soja) widely grows in limits of 23°57'～53°29'N and 97°04'～135°E in China. Wild soybean has the same genome (GG, 2n = 40) of cultivated soybeans and has become a valuable genetic resource for soybean breeding. Now the National Genebank has preserved 6494 wild soybean germplasm accessions, which will offer useful germplasm or genes for breeding, and also for theoretical research on the origion for soybean.The purpose of this study was to evaluate the extent of genetic diversity in the National Genebank Wild Soybean Collection, and to enhance the efficient utilization of the germplasm accessions. This study was conducted based on 70 pairs of SSR markers for the assessment for the National Genebank wild soybean samples using a set of mini-core collection of 96 accessions in China. Through this analysis, the genetic diversity in the Genebank Wild Soybean Clollection was made clearer. The results were as follows:1. The results showed an average of 18.3 alleles per locus and 10.6 alleles for the ecogeogarphical populations. The effective number of alleles per loci was 7.5. The ecogeographical populations deministrated that genetic diversity apeared with the highest value in the northeast, and decreased gradually toward south. There were an obvious genetic differentiation between the large seed type and the typical wild type, but they did not reach the extent between species; the large seed type still belong to wild soybean. The genetic distance and the geographical distance were positive relationship. The genetic distance between ecogeographical regions increased as geographical distances increased from north to south and the genetic distance between adjacent ecological regions was gradually increased. The genetic distance between southern region and other regions had relatively high value. The clustering of four ecogeographical regions showed that there were closer genetic differentiation between the germplasm pools from Northest and North China. The Changjiang Valley region and the southern region had greater genetic differentiation. This study showed that it was effective using the core collection to estimate genetic diversity of wild soybean rsources preserved in the National Genebank.2. Analysis of the genetic background for 96 accessions strongly suggested that large type accessions had the genetic background of cultivated soybean.3. The cluster analysis for 96 accesssions showed some regionality based on the SSR markers. However, the clusting of 96 accessions according to wild soybean agronomic traits showed weak regionality.4. Semi-wild soybean was inferred to originate from natural hyhridization between caultivated and wild soybeans. And also typical wild soybeans were inferred to have had introgression from cultivated soybeans. |
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