Detection of the pine wood nematode using a real-time PCR assay to target the DNA topoisomerase I gene

A species-specific real-time PCR assay targeting the DNA topoisomerase I gene has been developed to detect Bursaphelenchus xylophilus. The specificity of the assay was confirmed by the lack of amplification of genomic DNA from other Bursaphelenchus or Seinura species. The sensitivity test showed that the limit of the reaction was 0.01 ng of genomic DNA or one individual nematode, as small as an egg. The validity of the real-time PCR assay was evaluated by analyzing mixed nematode samples extracted from diseased pine trees in which B. xylophilus was associated with several closely related species, B. mucronatus, B. hofmanni, Aphelenchoides macronucleatus, S. lii and S. wuae. These results demonstrate the potential of the assay to provide rapid, specific and sensitive molecular identification of B. xylophilus for use in pest risk assessment and quarantine regulations.