Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2003
Publication Date: 11/15/2003
Citation: Chen, Y., Nelson, R.L. 2003. Genetic variation and relationships among cultivated, wild, and semi-wild soybean. Crop Science. 44:316-325. Interpretive Summary: There are two universally recognized species of soybeans. There is a third type that is intermediate between these two species but it is generally not recognized as a separate species. Classifying these intermediate types into one of the two species can be problematic. Our research demonstrated that there are three distinct groups that can be separated either by whole plant data or by comparing differences at the DNA level. The intermediate types were less genetically diverse as a group than samples of the standard types of the two species. Since all three types are sexually compatible, our results do not conclude that there should be three species but they do provide data about the relationships among and genetic diversities within these groups that will assist scientists in managing and utilizing the genetic diversity of soybeans.
Technical Abstract: Some Glycine accessions are intermediate between the standard phenotypes of G. ma and G. soja and have been labeled semi-wild. Few studies have examined both the genetic and phenotypic relationships among G. soja, G. max, and semi-wild types by combining morphological traits and DNA markers. The objectives of G. soja, G. max, and semi-wild accessions, to investigate the and semi-wild accessions, and to examine the relationships among phenotypes based on morphological traits and genotypes based on DNA markers. Ninety-two semi-wild, G. soja, and G. max accessions from the USDA Soybean Germplasm Collection were evaluated for twenty phenotypic traits and with RAPD markers. Mahalanobis distance and a Jaccard genetic similarity's matrixes were calculated for phenotypic traits and DNA data, respectively. Nonhierarchical and hierarchical clustering as well as multidimensional scaling (MDS) were used to evaluate relationships among semi-wild, G. soja, and G. max accessions. Principal component analysis was applied to identify the most significant morphological traits. There were 231 RAPD fragments generated by 44 primers of which 137 fragments were polymorphic. For these accessions, fragments were found that were unique for each taxonomic type. Three clusters defined by either phenotypic or DNA data are highly consistent and strongly corresponded to G. soja, G. max, and semi-wild classifications. Based on the analysis of RAPD data, G. soja accessions have the greatest genetic diversity and semi-wild accessions the least. G. max and semi-wild accessions are more closely related to each other than to G. soja accessions.