Potato cyst nematodes (Globodera rostochiensis and G-pallida) from Swedish potato cultivation -: an AFLP study of their genetic diversity and relationships to other European populations

Sixteen Swedish PCN populations (nine Globodera rostochiensis and seven G. pallida populations) were compared with 20 other European populations (nine G. rostochiensis and 11 G. pallida populations) from Germany, the Netherlands, Norway and the United Kingdom in an AFLP study. Seven AFLP primer combinations were used to amplify genomic DNAs extracted from cysts. A dendrogram, based on UPGMA and evaluated by bootstrap analysis, contained two main clusters, one for each species. The Swedish Ro1 populations were very similar to corresponding populations from other parts of Europe. Remaining G. rostochiensis populations appeared as a genetically heterogeneous group with two Swedish populations being most dissimilar. Within G. pallida there was strong support for differentiating Pal populations from Pa2/3 populations. All Swedish G. pallida populations were grouped in the Pa2/3 cluster, and there were indications that they might have two main European origins. On the whole, the study indicates that there is considerable heterogeneity in Swedish PCN populations, justifying the maintenance of effective phytosanitary regulations.