A range of studies the last decade has shown that modified wood can provide excellent protection against a range of wood deteriorating organisms, including decay fungi. However, we still lack information about why the modified wood is protected from microbial attack. An understanding of the mechanisms utilized by decay fungi when exposed to modified wood is important for further optimisation of new modified wood products. Several hypotheses have been put forward, but they still need testing.
The aim of this study was to summarize our earlier studies using molecular methods as a tool for better understanding of the mode of action of decay fungi in furfurylated wood. The studies include laboratory and field evaluations of decay colonisation patterns and gene expression.
For studying growth dynamics in furfurylated, CCA, Cu-HDO and untreated Scots pine sapwood the white-rot fungus Trametes versicolor qPCR was used. Incubation time was 2, 4, 6, 8 and 10 weeks. While the fungal colonisation in untreated control samples showed a continuous increase during the experimental period, the amount of fungal DNA in the treated samples had an initial peek after two weeks, followed by a gradual decline.
Stakes run for 6 years according to EN 252 were used for colonisation pattern studies. Results from chemical- and molecular methods together with microscopy analysis were compared. The results from the different evaluation methods indicated that the qPCR method is more sensitive than the other methods tested.
Gene expressions of the brown rot fungus Postia placenta after 2, 4 and 8 weeks were studied in furfurylated and untreated Scots pine sapwood under laboratory conditions. The main finding was that genes related to oxidative metabolic activity was higher in furfurylated wood compared to untreated Scots pine, and that carbohydrate metabolism related expression was lower in furfurylated wood compared to untreated control.
Also other studies revealing knowledge of the mode of action of furfurylated wood are discussed.
Keywords: Fungal colonization, furfurylation, gene expression, mode of action, quantitative real-time PCR
Authors
Pilgård A.
Université de Lorraine,LERMAB, France
Alfredsen G.
Université de Lorraine,LERMAB, France
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