RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM IN SOYBEAN GERMPLASM OF THE SOUTHERN USA

A soybean restriction fragment length polymorphism (RFLP) map (ISU/USDA ARS FCR, Ames, IA) was derived from an interspecific cross of Glycine mar (L.) Merr. x G. soja Siebold and Zucc. using early maturity group genotypes. We characterized the feasibility of the application of this map to physiologically distant soybean genotypes mainly maturity group (MG) V to IX. A total of 108 genotypes of G. max were surveyed. Germplasm represented ancestral genotypes, breeding lines and elite cultivars. The RFLP markers (83 probes) used in this research spanned fifteen major linkage groups at an average distance of 26 centimorgans (cM). Fifty four percent of the probes were noninformative. Thirty-five percent had a probability of detecting polymorphism between any two random genotypes with a frequency above 0.3. The RFLP probes detecting polymorphism with high frequency were identified. Restriction fragment length polymorphism was associated with cultivar pedigree and relation to ancestral genotypes. The majority of genotypes showed molecular similarities to 'Ralsoy', 'Dorman', 'Dunfield', and 'Ogden' germplasms; a smaller group of genotypes showed molecular similarities to S-100. Genotypic similarities were observed among most genotypes. However, genotypes of MG VI and VII retained potentially valuable levels of genetic diversity. Soybean cyst nematode and bacterial pustule resistance were present in many different genetic backgrounds and no association with donor genotypes was observed in principal components analysis. The set of identified RFLP probes with high frequency of polymorphism detection should serve as a core of molecular markers for initiating mapping of agronomic traits and detection of gene linkages across a wide range of maturity groups of cultivated soybean. Genomic diversity described by the principal components analysis may be useful in germplasm selection to develop populations for genome mapping in soybean.