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

A soybean restriction fragment length polymorphism (RFLP) map (ISU/USD A ARS FCR, Ames, IA) was derived from an interspecific cross of Glycin e mar (L.) Merr. x G. soja Siebold and Zucc. using early maturity grou p genotypes. We characterized the feasibility of the application of th is map to physiologically distant soybean genotypes mainly maturity gr oup (MG) V to IX. A total of 108 genotypes of G. max were surveyed. Ge rmplasm represented ancestral genotypes, breeding lines and elite cult ivars. The RFLP markers (83 probes) used in this research spanned fift een major linkage groups at an average distance of 26 centimorgans (cM ). Fifty four percent of the probes were noninformative. Thirty-five p ercent had a probability of detecting polymorphism between any two ran dom genotypes with a frequency above 0.3. The RFLP probes detecting po lymorphism with high frequency were identified. Restriction fragment l ength polymorphism was associated with cultivar pedigree and relation to ancestral genotypes. The majority of genotypes showed molecular sim ilarities to 'Ralsoy', 'Dorman', 'Dunfield', and 'Ogden' germplasms; a smaller group of genotypes showed molecular similarities to S-100. Ge notypic similarities were observed among most genotypes. However, geno types of MG VI and VII retained potentially valuable levels of genetic diversity. Soybean cyst nematode and bacterial pustule resistance wer e present in many different genetic backgrounds and no association wit h donor genotypes was observed in principal components analysis. The s et of identified RFLP probes with high frequency of polymorphism detec tion should serve as a core of molecular markers for initiating mappin g of agronomic traits and detection of gene linkages across a wide ran ge of maturity groups of cultivated soybean. Genomic diversity describ ed by the principal components analysis may be useful in germplasm sel ection to develop populations for genome mapping in soybean.