A rapid molecular diagnostic assay for the detection and identification of wood decay fungi of conifers

Wood decay fungi colonizing the root systems and boles of trees are often responsible for tree uprootings, thus resulting in significant damages especially in urban environment. Hence, an early detection and identification of hazardous wood decay agents may be pivotal during tree hazard assessment or phytosanitary surveys of urban trees. Molecular biology methods are increasingly used in diagnostics, providing efficient and sensitive tools for fungal detection. Furthermore, they allow the identification in the absence of fungal fruiting bodies. In 2007, a molecular diagnostic assay based on multiplex taxon-specific priming PCRs was developed and extensively used for the detection and identification of several wood decay fungi commonly associated to broadleaved trees. As a similar assay for the diagnosis of hazardous wood decay fungi of conifers was still lacking, in this study we designed and/or tested taxon-specific primers to be used in two multiplex PCRs for the detection and identification of twelve amongst the most widespread and harmful wood decay fungi of conifers in the northern hemisphere. Target fungi were: Armillaria spp., Echinodontium spp., Fomitopsis pinicola, Fuscoporia torulosa, Heterobasidion annosum sensu lato (s.l.), Laetiporus sulphureus, Onnia spp., Phaeolus schweinitzii, Phellinus weirii s.l., Pholiota spp., Porodaedalea spp. and Stereum spp. Sensitivity of this method was assessed in both multiplex endpoint PCRs and SYBR® Green Real time PCR assays. The assay was validated on 129 environmental samples comprising either fruiting bodies or decayed wood samples collected from conifer trees. This method may represent a simple, rapid and comprehensive diagnostic tool suitable to complement tree hazard assessment or phytosanitary surveys in parklands and urban settings.