The Genomic Impact of Selection for Virulence against Resistance in the Potato Cyst Nematode, .

Although the use of natural resistance is the most effective management approach against the potato cyst nematode (PCN) , the existence of pathotypes with different virulence characteristics constitutes a constraint towards this goal. Two resistance sources, (from ) and from ssp. CPC2802 (from the Commonwealth Potato Collection) are widely used in potato breeding programmes in European potato industry. However, the use of resistant cultivars may drive strong selection towards virulence, which allows the increase in frequency of virulent alleles in the population and therefore, the emergence of highly virulent nematode lineages. This study aimed to identify () genes in populations selected for virulence on the above resistance sources, and the genomic impact of selection processes on the nematode. The selection drive in the populations was found to be specific to their genetic background. At the genomic level, 11 genes were found that represent candidate genes. Most of the variant calls determining selection were associated with -selected populations, while many of them seem to be organised in genomic islands facilitating selection evolution. These phenotypic and genomic findings combined with histological studies performed revealed potential mechanisms underlying selection in .