P0943Imprints of Divergent Evolution and Artificial Selection in Oilseed Rape Breeding Pools
Imprints of Divergent Evolution and Artificial Selection in Oilseed Rape Breeding Pools
Brassica napus (rapeseed) has undergone intense artificial selection since the spontaneous hybridization of Brassica rapa and Brassica oleracea, the event which gave rise to this domesticated agricultural species. In rapeseed, the analysis of molecular diversity patterns can provide deep insight into the evolution of this crop, including intra- and interspecific diversification as well as genetic narrowing (bottleneck effect) associated with artificial selection pressure. High-density single-nucleotide polymorphism (SNP) genotyping provides a powerful platform to investigate diversity on a genome-wide scale.
We investigated genomic diversification between and within genetically distinct winter, semi-winter and spring oilseed rape breeding populations by genotyping a collection of 883 highly homozygous breeding lines with the Brassica 60k SNP Illumina array. Linkage disequilibrium (LD) and genome diversity at the population and chromosome level were assessed in conjunction with pairwise comparisons of Extended Haplotype Homozygosity (EHH) between subgroups.
Genome-wide evaluation indicated strongly eroded genetic diversity across several chromosome regions. Extensive patterns of LD were observed within all B. napus subgroups examined, especially in the C-subgenome. Furthermore, the arrangement of the identified selective sweeps indicated divergent evolutionary processes between geographically diverse genepools. These findings provide valuable knowledge for the establishment and improvement of heterotic pools for rapeseed hybrid breeding as well as fundamental insights into the genomic architecture of rapeseed, thereby enabling further inferences about the evolution history of this species.
We investigated genomic diversification between and within genetically distinct winter, semi-winter and spring oilseed rape breeding populations by genotyping a collection of 883 highly homozygous breeding lines with the Brassica 60k SNP Illumina array. Linkage disequilibrium (LD) and genome diversity at the population and chromosome level were assessed in conjunction with pairwise comparisons of Extended Haplotype Homozygosity (EHH) between subgroups.
Genome-wide evaluation indicated strongly eroded genetic diversity across several chromosome regions. Extensive patterns of LD were observed within all B. napus subgroups examined, especially in the C-subgenome. Furthermore, the arrangement of the identified selective sweeps indicated divergent evolutionary processes between geographically diverse genepools. These findings provide valuable knowledge for the establishment and improvement of heterotic pools for rapeseed hybrid breeding as well as fundamental insights into the genomic architecture of rapeseed, thereby enabling further inferences about the evolution history of this species.