QTL Mapping of Soybean Aphid Resistance In Soybean Genotype K1621.

The soybean aphid (Aphis glycines Matsumura) has been one of the major pests of soybean [Glycine max (L.) Merr.] in soybean-growing regions of North America since it was first reported in 2000. K1621 is a soybean genotype with moderate resistance to the soybean aphid Biotype 1. The objectives of this study were to map and validate the resistance gene in K1621 using simple sequence repeat (SSR) markers. A mapping population of 150 F_2:3 families from the cross between K1621 and susceptible genotype KS4202 were evaluated for aphid resistance. Phenotyping was conducted on the basis of total aphid number per plant seven days following infestation with four aphids. After SSR markers for polymorphism were screened between parents, a total of 133 polymorphic markers distributed across the soybean genome were used for genotyping. One quantitative trait loci (QTL) controlling antibiotic resistance was found by using the composite interval mapping method. This QTL localized on chromosome 13 (linkage group F) between markers Sat_234 and S6814 explained 54% of the phenotypic variation in aphid number. The putative QTL was further validated by single marker analysis using an independent population derived from the cross of K1621 and Dowling. The marker identified and validated in this study could be useful for marker-assisted selection. Ancestry study indicated soybean aphid resistance in K1621 might be inherited from Palmetto.