Genetic mapping of three quantitative trait loci for soybean aphid resistance in PI 567324

Host-plant resistance is an effective method for controlling soybean aphid (Aphisglycines Matsumura), the most damaging insect pest of soybean (Glycine max(L.) Merr.) in North America. Recently, resistant soybean lines have been discovered andat least four aphid resistance genes (Rag1, Rag2, Rag3 andrag4) have been mapped on different soybean chromosomes. However, the evolutionof new soybean aphid biotypes capable of defeating host-plant resistance conferred by mostsingle genes demonstrates the need for finding germplasm with multigenic resistance to theaphid. This study was conducted to map quantitative trait loci (QTL) for aphid resistancein PI 567324. We identified two major QTL (QTL_13_1 and QTL_13_2) for aphid resistance onsoybean chromosome 13 using 184 recombinant inbred lines from a ‘Wyandot''× PI 567324 cross. QTL_13_1 was located close to the previously reportedRag2 gene locus, and QTL_13_2 was close to the rag4 locus. A minor QTL(QTL_6_1) was also detected on chromosome 6, where no gene for soybean aphid resistancehas been reported so far. These results indicate that PI 567324 possesses oligogenicresistance to the soybean aphid. The molecular markers closely linked to the QTL reportedhere will be useful for development of cultivars with oligogenic resistance that areexpected to provide broader and more durable resistance against soybean aphids comparedwith cultivars with monogenic resistance.