Genetic variation in Globodera pallida linked to virulence in North-West Europe

The cyst nematode Globodera pallida is an important pest in potato. Originating from South America, the species has been introduced in Europe approximately one and a halve century ago. After its introduction the nematode has spread over the continent and is currently found in almost all potato producing countries. Furthermore, various control measures, including resistance genes, have been applied to keep populations from causing yield losses. We suspect that these control measures have shaped the genetic variation within and between European populations. Here, we present genetic links between virulence arisen by artificial and agronomical selection of Dutch G. pallida populations.
We conducted container tests characterizing the virulence of 15 recently collected G. pallida populations on a total of 28 potato cultivars. We determined that these new populations were virulent and that (remaining) potato resistance could be characterized by two main clusters. Selection of two of these populations on the potato cultivar Seresta resulted in an increased virulence. The genetic diversity of the selected and the other field populations was determined based on variant calling using a newly constructed G. pallida reference genome. We thus identified a region that was consistently selected for and associated with increased virulence on Seresta.
Our findings fit within the context of earlier observations from France and Germany, where it was found that G. pallida populations could be (artificially) selected for virulence. Given the concurrent rise of virulence in these populations within The Netherlands and the broader North-West of Europe is suggestive that this potential for virulence is wide-spread within the European populations.