Genetic diversity of soybean germplasm resistant to Heterodera glycines

Information on the genetic background of soybean Glycine max (L.) Merr.] germplasm resistant to Soybean Cyst Nematode (SCN) (Heterodera glycines Ichinohe) is essential for developing plant breeding strategies, however, pedigree information for SCN resistant germplasm is not always available. Using restriction fragment length polymorphisms (RFLPs) to fingerprint different soybean lines is a useful means of determining genetic relationships and identifying unique genotypes. In this study, 102 soybean genomic probes with five different restriction enzymes were used to detect DNA variations and investigate genetic relationships among 56 soybean plant introductions (PIs) and cultivars. Among 510 probe/enzyme combinations, a total of 1707 hybridization bands were generated, of which 501 were polymorphic. A cluster dendrogram and a principal component analysis (PCA) plot diagram were constructed using DNA fingerprinting of the 56 soybean lines. Based on the clustering and PCA analyses, two major clusters comprising 15 groups were identified for the PIs and cultivars in the dendrogram. Reactions to different race isolates of SCN were distinguishable among different groupings of the clusters and PCA results, and various origins of the PIs and the pedigree information of the cultivars could be associated with the different clusters. Additional information on the appropriate number of probes used to detect genetic diversity more efficiently was elucidated through this research. We believe that the genetic relationships determined among these 56 soybean lines could provide useful information in identifying unique sources of genes for SCN resistance. This revised version was published online in July 2006 with corrections to the Cover Date.