Soybean mosaic virus (SMV) is a prevalent viral pathogen of soybean [Glycine max (L,) Merr,] wherever it is grown. Several genes that confer resistance in soybean to soybean mosaic virus have been identified. One of these resistance loci, Rsv4, confers resistance to all the known strain groups of SMV. This study was conducted to determine the map position of the Rsv4 lotus in the soybean genome. A population of 255 F-2 individuals from the cross of the SMV resistant line LR2 (Rsv4) by the susceptible line Lee68 (rsv4) was evaluated in a mapping study. DNA from 12 to 15 F-2 individuals being either homozygous resistant or susceptible were pooled to produce bulk resistant and bulk susceptible DNA samples. Parents and bulks were screened with 101 AFLP primer pairs and two linked polymorphisms were identified. A putative linked marker, amplified by the primers Mse-AAA and Eco-AAG, was converted to a restriction fragment length polymorphism (RFLP) clone and a single polymorphic hand was mapped 4.8 cM away from Rsv4. The same band was mapped in a second population containing 400 mapped loci and it was determined that this marker was located on the soybean Dib linkage group, Subsequent mapping in the original Rsv4 mapping population showed that the Rsv4 locus is flanked by the microsatellite markers, Satt542 at 4.7 cM and Satt558 at 7.8 cM.
