Intraspecific variation in isolates of Bursaphelenchus xylophilus (Nematoda: Aphelenchoididae) revealed by ISSR and RAPD fingerprints

The pinewood nematode Bursaphelenchus xylophilus is the causal agent of pine wilt disease. In order to trace the origin of its recently introduced Portuguese population, two PCR-based techniques, random amplified polymorphic DNA (RAPD) and inter-simple sequence repeats (ISSR), were used to determine genetic relationships among 30 B. xylophilus isolates from the Usa, Canada, Japan, China, South Korea and Portugal. Fingerprints obtained with both methods detected a reduced genetic variation of introduced popula- tions as compared to native North American populations. Cluster analyses of genetic distances between isolates were carried out and bootstrap dendrograms were constructed. The results indicated that founders of the Portuguese popula- tions most likely were translocated one or two times to Portugal from their colonized sites in East Asia, but not from their native habitats in North America.