RFLP ANALYSIS OF CHLORIMURON ETHYL SENSITIVITY IN SOYBEAN

Soybean [Glycine max (L.) Merr.] genotypes are known to differ in thei r chlorimuron ethyl sensitivity (CS). These differences are believed t o be controlled by a few major genes. However, the genes controlling C S are probably not the same for all soybean genotypes. Information on the number of genes and their genomic location can be determined by mo lecular mapping of CS. A restriction fragment length polymorphism (RFL P) map was constructed from a soybean population of 111 F-2-derived li nes of a Pr 97100xCoker 237 cross. The purpose of this study was to id entify and map the loci controlling CS in soybean. The F-2-derived lin es were grown at Athens, Georgia, and Blackville, South Carolina, in 1 995, treated with chlorimuron ethyl, and scored for CS. The genetic ma p, involving 162 marker loci, covered about 1600 cM, with an average d istance of 10.7 cM between two adjacent marker loci. In this populatio n 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 a s 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. Thi s locus explained as much as 88% of the variation in CS, whereas the m inor locus explained about 11% of the variation. Thus, we have identif ied and located the single major locus along with a previously unknown minor locus for CS in soybean.