RFLP analysis of chlorimuron ethyl sensitivity in soybean

Soybean [Glycine max (L.) Merr.] genotypes are known to differ in their chlorimuron ethyl sensitivity (CS). These differences are believed to be controlled by a few major genes. However, the genes controlling CS are probably not the same for all soybean genotypes. Information on the number of genes and their genomic location can be determined by molecular mapping of CS. A restriction fragment length polymorphism (RFLP) map was constructed from a soybean population of 111 F2-derived lines of a PI 97100 X Coker 237 cross. The purpose of this study was to identify and map the loci controlling CS in soybean. The F2-derived lines were grown at Athens, Georgia, and Blackville, South Carolina, in 1995, treated with chlorimuron ethyl, and scored for CS. The genetic map, involving 162 marker loci, covered about 1600 cM, with an average distance of 10.7 cM between two adjacent marker loci. In this population CS was conditioned by one major locus on the USDA linkage group (LG) E and one minor locus on an unknown linkage group at both locations as well as combined over locations. The most probable genomic location of the major locus was 2.8 cM from the RFLP locus cr168-1 on LG E. This locus explained as much as 88% of the variation in CS, whereas the minor locus explained about 11% of the variation. Thus, we have identified and located the single major locus along with a previously unknown minor locus for CS in soybean.