Fig. 1. Five breeding schemes (Breeding Plan 2 to 6) for marker-assisted introgression of two genes and a reference scheme (Breeding Plan 1) for introgression of two genes without background selection. D^A and D^B are the donor lines of the target genes, R is the recipient line. The symbols denote: | no selection, selection only for presence of the target gene(s), selection for presence of the target gene(s) and marker-assisted background selection, x crossing, and selfing, , , and indicate generations with crossing, backcrossing, and selfing, respectively.