Two microsatellite markers that flank the major soybean cyst nematode resistance locus

The use of resistant cultivars is the most effective method for controlling soybean cyst nematode (Heterodera glycines Ichinoe; SCN) on soybean [Glycine max (L.) Merrill]. However, resistance to SCN is oligogenic, making inheritance patterns complex and breeding difficult. One major partial-resistance locus for SCN resistance is located on molecular linkage group (MLG) 'G'. This locus controls more than 50% of variation associated with response to SCN and resistant alleles are present in many important sources of SCN resistance, including PI 209332, PI 88788, PI 90763, PI 437654, and 'Peking'. Restriction fragment length polymorphisms (RFLPs) linked to the major SCN resistance alleles on MLG G have proven effective in tracking the alleles and predicting SCN response. These RFLPs are much more efficient in terms of time and labor than greenhouse assays for SCN. Nevertheless, more efficient DNA markers are needed in screen the many lines required for marker-assisted selection. Polymerase chain reaction-based markers, such as microsatellites (simple sequence repeats), have been sought because they are faster, less expensive, more polymorphic, and require less labor than RFLPs. In this study, we report two microsatellites. BARC-Satt038 and BARC-Satt130, that flank the major SCN resistance locus on MLG G. These microsatellites efficiently identify the chromosome fragment carrying the resistance allele and are also good predictors of SCN phenotype response.