CLUSTER-ANALYSIS OF 36 GLOBODERA-PALLIDA FIELD POPULATIONS USING 2 SETS OF MOLECULAR MARKERS

Thirty-six populations of the potato cyst nematode Globodera pallida, all collected in the Netherlands, were analysed twice: by two-dimensio nal gel electrophoresis of proteins (2-DGE) and by random amplified po lymorphic DNA fingerprinting (RAPD). Two-DGE revealed frequencies of 2 1 alleles at eight putative loci in each population. The same populati ons were subjected to RAPD analysis. This qualitative technique reveal ed 38 polymorphic DNA fragments. Both datasets were independently proc essed to determine the intraspecific variation. UPGMA analysis resulte d in a 2-DGE- and a RAPD-based dendrogram with cophenetic correlation coefficients of 0.755 and 0.838 respectively. The correlation between the genetic similarity values for the populations was 0.572. Compariso n between the 2-DGE- and the RAPD-based dendrogram revealed that only thirteen of the 36 populations analysed were clustered identically. It is concluded that the gene pool similarity concept is only in some in stances applicable to Dutch populations of G. pallida. For populations that could not be differentiated unequivocally on the basis of molecu lar markers, markers closely linked to avirulence genes should be iden tified. Approaches that will lead to the identification of such marker s are discussed.