Association of RFLP markers with loci conferring broad-based resistance to the soybean cyst nematode (Heterodera glycines).

Soybean cyst nematode (SCN) is a major soybean yield-limiting pest. The present study was conducted to map broad-based SCN resistance loci from the cultivar 'Hartwig'. Two-hundred F2∶3 lines derived from the cross 'Williams 82' x 'Hartwig' were screened with a fourth-generation SCN inbred and 56 polymorphic molecular markers. Allele states and phenotypes were analyzed using stepwise regression and the model selection was made at P [Symbol: see text] 0.01. Four unlinked RFLP markers (A006, A567, A487, A112) were associated with SCN resistance and the partial coefficient of determinations (R(2)) were 91%, 1%, 1%, and 1%. We have mapped a new, major SCN resistance locus (A006) and three minor loci (A567, A487, A112). This complete mapping will accelerate the transfer of broad-based resistance without linkage drag and aid in the determination of relationships among various SCN-resistant germplasm sources.