Genome mapping of soybean cyst nematode resistance genes in 'Peking', PI 90763 and PI 88788 using DNA markers

Several sources of soybean cyst nematode (Heterodera glycines Ichinohe; SCN) resistance have been identified in soybean [Glycine max (L.) Merrill]; yet, the genetic basis of this economically important trait remains poorly characterized. This study was conducted to identify quantitative trait loci that control disease response in three commonly used sources of SCN resistance. Using genetic markers, we analyzed three segregating soybean F2 populations ['Evans' x 'Peking', Evans x Plant Introduction (PI) 90763, and Evans x PI 88788] and compared the results with those of a previous study involving PI 209332. For the Peking, PI 90763, and PI 209332 populations, races 1, 3, and 6 were used as SCN inoculum; for the PI 88788 population, only races 3 and 6 were used. To uncover putative resistance loci, F2 DNA marker genotypes at between 63 and 99 loci in each population were contrasted with cyst indices averaged from 12 F2:3 progeny individuals. Four independent partial SCN resistance loci were uncovered at P