title: Lack of Genetic Variation of Bursaphelenchus xylophilus in Portugal Revealed by RAPD-PCR Analyses.
abstract: Random Amplified Polymorphic DNA (RAPD-PCR) technique was used to assess the level of genetic variability and genetic relationships among 24 Portuguese isolates of pinewood nematode, Bursaphelenchus xylophilus. The isolates represent the main infested areas of Portugal. Two additional isolates of B. xylophilus representing North America and East Asia were included, and B. mucronatus was used as out-group. Twenty-eight random primers generated a total of 640 DNA fragments. The Nei and Li similarity index revealed a high genetic similarity among the Portuguese isolates (above 90%). Hierarchical cluster analysis was performed to illustrate the relatedness among the isolates. No indication for separate groups among the Portuguese isolates was obtained, and the low level of genetic diversity strongly suggests that they were dispersed recently from a single introduction. The lack of apparent relationship between the genetic and the geographic matrices of the Portuguese isolates limits the use of this technique for following recent pathways of distribution. Genetic distance of the Portuguese isolates towards an isolate from China was much lower as compared to an isolate from the USA. This confirmed previous results suggesting an East Asian origin of the Portuguese B. xylophilus.
authors.affiliation: NemaLab-ICAM, Departamento de Biologia, Universidade de Evora, 7002-554 Evora, Portugal Institute for Plant Virology, Microbiology and Biosafety, Federal Biological Research Centre for Agriculture and Forestry (BBA), Messeweg 11-12, D-38104 Braunschweig, Germany.
authors.forename: Paulo
authors.initials: P
authors.lastname: Vieira
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Burgermeister
authors.forename: Manuel
authors.initials: M
authors.lastname: Mota
authors.forename: Kai
authors.initials: K
authors.lastname: Metge
authors.forename: Gonçalo
authors.initials: G
authors.lastname: Silva