Estimation of Recombination Frequencies and Construction of RFLP Linkage Maps in Plants from Crosses between Heterozygous Parents

The construction of a restriction fragment length polymorphism (RFLP) linkage map is based on the estimation of recombination frequencies between genetic loci and on the determination of the linear order of loci in linkage groups. RFLP loci can be identified as segregations of singular or allelic DNA-restriction fragments. From crosses between heterozygous individuals several allele (fragment) configurations are possible, and this leads to a set of formulas for the evaluation of p, the recombination frequency between two loci. Tables and figures are presented illustrating a general outline of gene mapping using heterozygous populations. The method encompasses as special cases the mapping of loci from segregating populations of pure lines. Formulas for deriving the recombination frequencies and information functions are given for different fragment configurations. Information functions derived for relevant configurations are also compared. A procedure for map construction is presented, as it has been applied to RFLP mapping in an allogamous crop.