Variability for Recombination Frequencies in the AP12 Soybean Population

Abstract

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 F1 generation would be as effective in breaking linkages as one generation of intermating of F2 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 F2 populations of 50 AP12 individuals crossed with each of three ‘Clark’ near isolines containing the respective linkage groups P1r, lnp2, and dt1L1. 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.