Genetic linkage map of B. napus. Linkage groups are arranged according to the regions of primary homology between the A (N1–N10) and C (N11–N19) genomes (Parkin et al. 2003), with centimorgan distances indicated to the left of each group. Each genetic locus is colored according to the presumed Arabidopsis homolog: light blue, chromosome 1; orange, chromosome 2; dark blue, chromosome 3; green, chromosome 4; and red, chromosome 5. Loci in italics were found within conserved blocks on the basis of secondary or tertiary hits within the Arabidopsis genome. Loci duplicated within a B. napus linkage group are indicated by vertical lines to the right of the group. Identified genome blocks showing conservation of marker content and marker order between the Arabidopsis and B. napus genomes are shown to the left of each linkage group. Each block is colored and labeled according to the identified homologous region in Arabidopsis (see Figure 2). Inversions identified in Brassica relative to Arabidopsis are indicated by arrows. Regions of the B. napus genome that have been tentatively aligned with Arabidopsis centromeric regions are indicated by hatched blocks.

Distribution of the physical distance in Arabidopsis compared to the genetic distance in B. napus for each pair of linked comparative markers found with the conserved blocks.

A representation of the Arabidopsis genome based on the primary location of each sequenced B. napus RFLP marker on the Arabidopsis pseudochromosomes (megabase distances are indicated to the right of the chromosomes). Duplicate marker locations are indicated in parentheses. Blocks of markers found to be genetically linked in B. napus are indicated by shading and capital letters (A–F). In the majority of cases, C4B is conserved as a complete block, but in two instances, on N4 and N14, a small section of the block was observed and is represented by C4B′.

Alignment of segment of B. napus linkage group N19 with both Arabidopsis chromosome 1 and chromosome 5, highlighting the difficulty in identifying the most related Arabidopsis region where there are ancient duplications in the model genome.