Using RAPD markers to analyse genetic diversity in Portuguese potato cyst nematode populations

The two species of potato cyst nematodes (PCN) have different spectra of virulence towards host resistance genes and a proper identification is important in the control of these nematodes by means of resistant potato cultivars. Genetic variability of 32 populations of Globodera rostochiensis and three of G. pallida from different regions of Portugal were analysed and compared using random amplified polymorphic DNA and sixteen primers. In addition, a population of G. pallida (Luffness) from Scotland, UK, was included for comparison. The patterns obtained were evaluated using the Nei coefficient and the UPGMA cluster method. The resulting clusters were expressed as dendrograms in the Phylogeny Inference Package (PHYLIP) program. Separation of the two species of PCN was achieved with an average similarity of 43%. Two populations of G. rostochiensis (PT1 and PT82) appear to be distinct from the main group of this species. One population of G. pallida (PT104) was distinct from the others of this species and the Luffness population was linked most closely with PT5701. Distinct clusters were observed within both species but the clusters could not be related to the geographic proximity of the populations.