The Pd2 and Lf2 loci define soybean linkage group 16

Despite progress made in constructing the molecular map of soybean [Glycine mar (L.) Merr.], many genes remain to be located on the classical map. The genetic linkage studies reported here were undertaken to advance the construction of the classical genetic map. Hybridizations were made in the field and the F-2 and F-3 generations were produced and classified in the greenhouse or field at Beltsville, MD. Data were tested by chi-square for single-factor segregation and linkage. Recombination estimates were made by the maximum likelihood method. The Lf2 locus (controlling leaflet number) segregated independently of the T, Ln, W1, Rj1, F, Y17, Df4, Fr2, and Pc loci. The Pd2 locus (controlling pubescence density) segregated independently of the W1 locus. The chi-square for Lf2 and Pd2 strongly indicated linkage. The recombination frequency between the Lf2 and Pd2 loci was estimated at 12 +/- 2.2%. Soybean breeders attempting to couple or decouple the Lf2 and Pd2 alleles in their breeding populations should take cognizance of this linkage association in estimating the population sizes required to achieve their goals.