Figure 2. Effects of donor segments containing homoeologous transpositions on seed yield in double haploid (DH) lines and testcross (TC) progenies of Brassica napus. The homoeologous relationships of chromosomes derived from the diploid progenitor species B. rapa (N1–N10, black) and B. oleracea (N11–N19, white) are shown using lines to connect homologous restriction fragment length polymorphism (RFLP) loci from the genetic maps (Udall et al. 2005). The configurations of homoeologous chromosomal transpositions are indicated for the spring parent used to develop the DH mapping populations (segments of N1 on N11, N7 on N16, N16 on N7, and N19 on N10). The configurations of unadapted donor parent transpositions are shown right adjacent to spring parent chromosomes (N10, N11, N13, and N16). The boxed area highlights the effect of donor segments on intersubgenome heterozygosity. Arrows indicate significant increases (up) or decreases (down) in seed yield associated with the introgression of alleles from the donors listed for DH lines or TC progenies, as indicated. The range of variation explained by these genomic regions in different test environments where significant effects were observed is shown by R² value (Quijada et al. 2006; Udall et al. 2006). MF216 was the designation of the parent containing introgressions from Major, and it also contained introgressions from the spring cultivar Stellar, which accounted for the transposition on N13. Resistance (R) or susceptibility (S) to a bacterial disease was associated with N10 segments from spring parent (R), donor (S), and tester (R).