Poster Abstract
  Molecular and Microscopic Analysis

Detection and Identification of Phytophthora ramorum Causal Agent of Sudden Oak Death by Molecular Beacon

G. Bilodeau¹, C.A. Lévesque², A.W.A.M. De Cock³, G. Kristjansson⁴, J. McDonald⁴, R.C. Hamelin⁵

Phytophthora ramorum, the causal agent of the Sudden Oak Death (SOD), is decimating oak trees in California. This disease is spreading rapidly. A quarantine is currently in effect to prevent spread and eradication is being attempted in Southern Oregon where the disease was found recently. New methods are being developed to detect and identify the pathogen reliably in order to implement this quarantine. The most commonly used assay is based on Internal Transcribed Spacer (ITS) DNA analysis. However this assay cannot distinguish reliably between Phytophthora ramorum and Phytophthora lateralis. In order to overcome this problem, the Beta-tubulin gene was sequenced and more polymorphisms between these two species and between Phytophthora ramorum and other Phytophthora were found compared to the ITS region. Specific primers for Allelic Specific Polymerase Chain Reaction (AS-PCR) and molecular beacons have been developed to detect and identify this pathogen. The primers are Lock Nucleic Acids (LNA) which show a high specificity and yield. The preliminary assay with the molecular beacon and the primers differentiate P.ramorum from the different species. This new assay will be validated this fall using Canadian Food Inspection Agency (CFIA) and USDA-APHIS samples from the survey.

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¹Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, P.O. Box 3800, 1055 du P.E.P.S., Sainte-Foy, Quebec, G1V 4C7, Canada; (418) 648-5824; gbilodeau@cfl.forestry.ca
²ECORC, Agriculture and Agri-food Canada, 960 Carling avenue, Ottawa,Ontario, K1A 0C6, Canada
³Centraalbureau voor Schimmelcultures, P.O.Box 85167, NL-3508 AD Utrecht, The Netherlands
⁴Pest DNA Diagnostics Laboratory, Centre for Plant Quarantine Pests, CFIA, 3851 Fallowfield Rd, Ottawa, Ontario, K2H 8P9, Canada
⁵Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, P.O. Box 3800, 1055 du P.E.P.S., Sainte-Foy, Quebec, G1V 4C7, Canada