RFLP mapping using near-isogenic lines in the soybean [Glycine max (L.) Merr.]

A molecular marker analysis of a near-isogenic line (NIL), its donor parent (DP), and its recurrent parent (RP) can provide information about linkages between molecular markers and a conventional marker introgressed into the NIL. If the DP and RP possess different alleles for a given molecular marker, and if the NIL possesses the same allele as the DP, then it is reasonable to presume a linkage between that molecular marker and the introgressed marker. In this study, we examined the utility of RFLPs as molecular markers for the NIL genemapping approach. The allelic status of fifteen RFLP loci was determined in 116 soybean RP/NIL/DP line sets; 66 of the 'Clark' RP type and 50 of the 'Harosoy' RP type. Of the 1740 possible allelic comparisons (116 NILs x 15 RFLP loci), 1638 were tested and 462 (33.9%) of those were informative (i.e., the RP and DP had different RFLP alleles). In 15 (3.2%) of these 462 cases the NIL possessed the DP-derived RFLP allele, leading to a presumption of linkage between the RFLP locus and the introgressed conventional marker locus. Two presumptive linkages, pK-3 - and pK-472 - L f_i, were subsequently confirmed by cosegregation linkage analysis. Although not yet confirmed, two other associations, pk-7 ab and pK-229 - y₉ seemed to be plausible linkages, primarily because the pk-7 - ab association was detected in two independently derived NILs and both markers of the pK-229 - y₉ association were known to be linked to Pb. The data obtained in this investigation indicated that RFLP loci were useful molecular markers for the NIL gene-mapping technique.