Molecular Mapping of Genetic Resistance to Soybean Cyst Nematode in SS97-6946.

Soybean Cyst Nematode (SCN) (Heterodera glycine) is the most damaging pest of soybean and estimated annual yield losses are 720 million dollars annually in USA. Breeding resistant cultivars is the most efficient means to control SCN but the nematode has adapted and overcome resistance of developed soybean cultivars due to narrow genetic base. Resistant genes for different HG types have been genetically mapped in several soybean accessions but most of them have common quantitative trait loci (QTL). SS97-6946 is resistant to different SCN races/HG types and could have novel genes for SCN resistance. A study was initiated in summer 2007 to investigate the genetics of resistance to SCN and identify QTLs conferring broad-spectrum SCN resistance in SS97-6946. A cross between PI567476 and SS97-6946 was made in the summer of 2006. Leaves of 212 F₂ individuals from the cross PI567476 X SS97-6946 were collected to isolate DNA in summer 2007. 365 polymorphic SSR primer pairs out of 545 were used to genotype the F₂ plants. Seeds from 160 F_2:3 families were evaluated against HG types 2.5.7, 1.2.5.7, 0 and 1.2.7 (races I, II, III and V) for SCN bioassay following standard protocol.