Canadian Forest Service Publications

Real-time PCR detection and discrimination of the Ceratocystis coerulescens complex and of the fungal species from the Ceratocystis polonica complex validated on pure cultures and bark beetle vectors. 2014. Lamarche, J.; Stewart, D.; Pelletier, G.; Hamelin, R.C.; Tanguay, P. Can. J. For. Res. 44:1103-1111.

Year: 2014

Issued by: Laurentian Forestry Centre

Catalog ID: 35680

Language: English

Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.1139/cjfr-2014-0082

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Eight Ceratocystis Ellis & Halst. species belonging to the Ceratocystis coerulescens complex are pathogens causing bluestain on Pinaceae. Three of these species, namely C. polonica, C. laricicola, and C. fujiensis, are particularly aggressive and can cause tree mortality. Although currently absent from the North American landscape, they are considered a significant potential threat to the Canadian boreal forest. As they are difficult to distinguish from native North American species belonging to the C. coerulescens complex, we developed a real-time PCR detection test for each of the three species to detect the equivalent of one fungal spore directly from insect vectors. DNA from at least one species of the C. coerulescens complex was detected on 86% of the beetles (Ips typographus (Linnaeus, 1758) and Ips cembrae (Heer, 1836)), whereas C. polonica DNA was detected on 60% of the I. typographus and C. laricicola DNA was detected on 84% of the I. cembrae. Between 20 and 344 225 spore equivalents were detected on the beetle specimens, and no inhibition effect of DNA extract from environmental samples was observed. These molecular detection tools will allow for rapid and reliable detection of C. polonica, C. laricicola, or C. fujiensis, allowing for a rapid implementation of eradication measures in case of introduction into Canada.

Plain Language Summary

Several fungi can cause blue stain in wood. Among them are species of the genus Ceratocystis, which attack conifers. Three of these species (C. polonica, C. laricicola and C. fujiensis), which are spread by beetles, can cause tree mortality.

Although presently absent from the North American landscape, these fungal species are considered a significant potential threat to Canada's boreal forest. In order to distinguish them from native North American species, researchers have developed tests to detect these pathogenic fungi directly from environmental samples such as insects or woody tissues.

These molecular detection tools were initially transferred to the Canadian Food Inspection Agency (CFIA). They can be used for rapid and reliable detection, and will prevent the introduction of these species into Canada and mitigate their impacts. The CFIA’s evaluation of these tools and their possible use in the detection of these fungi could result in changes to Canada’s import regulations regarding conifer products.