Fig. 2.

Homeologous nonreciprocal transpositions (HNRTs) or homeologous exchanges (HEs) between B. napus chromosomes A2 and C2. Coverage depth was obtained after mapping Illumina sequence reads to the reference genome of B. napus. Segmental HEs are revealed based on sequence read coverage analysis, where a duplication (red) is revealed by geater coverage for a given segment than the rest of the genome (black) and a deletion (blue) by little or no coverage for the corresponding homeologous segment. The X axis indicated the chromosome length, sizes of chromosomes are indicated in Mb. The Y axis showed the coverage depth of sequence reads mapped to the reference. The red lines indicated HNRT or HE occurred between the two chromosomes.