Variability for Recombination Frequencies in the AP12 Soybean Population

Repeated intermating in a plant‐breeding procedure increases the number of meiotic cycles and the opportunities to break genetic linkages, but it also increases the number of generations required to complete a round of the procedure. Because a 50% increase in recombination over the normal level in an F 1 generation would be as effective in breaking linkages as one generation of intermating of F 2 individuals, genetic control of recombination might be usable in place of repeated intermating. The objectives of this study were to determine if variability in recombination frequency exists in the API2 soybean [ Glycine max (L.) Merr.] population and to isolate genotypes with increased or decreased recombination rates. Recombination frequencies were measured in F 2 populations of 50 AP12 individuals crossed with each of three ‘Clark’ near isolines containing the respective linkage groups P 1 r , lnp 2 , and dt 1 L 1 . For each of the three linkage groups, significant ( P ≤ 0.05) variability for recombination frequency existed among individuals in the AP12 population, and the recombination frequencies were normal|y distributed. As in many other organisms, recombination frequency of soybean appears to be under polygenic control. Correlation coefficients of recombination frequencies among individuals across the three linkage groups were nonsignificant ( P > 0.05). Although genotypes were present with recombination frequencies above or below the population mean for all the linkage groups, a genotype that generally enhances or represses recombination was not isolated.