Predicting the properties of pure breeding lines extractable from a cross in the presence of linkage

Abstract

The quantitative consequences of using estimates of additive genetic components of variation from the early generations of a cross to predict the properties of the pure breeding lines extractable from it when there is a linkage disequilibrium are investigated theoretically and by examples drawn from the cross of varieties 1 and 5 of Nicotiana rustica. In the presence of a linkage disequilibrium very good predictions can be obtained by combining estimates of the rank 1 and 2 forms of the additive genetic component of variation which can be estimated from F3 and S3 families of a cross. These predictions can be marginally improved by also estimating the rank 3 form but this requires the addition of F4 families.