Modified wood can provide protection against a range of wood deteriorating organisms. Several hypotheses have been put forward for the mode of action against wood decaying fungi, including inhibition of action of specific enzymes, but they still need further testing. This paper summarizes results from a project focusing on molecular studies of fungal colonization in modified wood. The focus has been on furfurylated wood, but also thermally modified and acetylated wood has been studied.
Among the main finding was that wood modifications have an effect on the exploitation face of both brown and white rot colonization, but not on the exploration face. As already reported in a range of papers wood modification effects the wood moisture content, and this was confirmed within this project. New information was gathered about the effect on gene expression. Even before any mass loss was detected, differences in gene expression were measured. Within an eight week period, genes related to oxidative metabolic activity of P. placenta generally was higher in furfurylated wood compared to untreated Scots pine. Carbohydrate metabolism related expression varied. A similar comparison was done, but with longer incubation time and also including thermal modification and acetylation. In the beginning of the incubation of all treated wood samples, the genes coding for oxidative metabolic activity had higher expression levels than the untreated control. In the end of the incubation most of these genes were less expressed than in the untreated control. The genes used for carbohydrate metabolism and the alcohol oxidase showed a significant decrease after 14 weeks of incubation. At the same time an increase in gene expression of an enzyme putative involved in lignin decomposition was detected. It was also shown that the use of molecular methods in field trial evaluation can contribute with important additional information to the standard evaluation methods.
Keywords: fungal colonization, gene expression, mode of action, quantitative real time PCR, wood modification
Authors
Alfredsen G.
Norwegian Forest and Landscape Institute, Ås, Norway
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