Since brown rot fungi prefer conifers it is the most important wood decaying group in the boreal forest belt (Zabel and Morrell 1992, Goodell 2003, Vanden Wymelenberg et al. 2010). Especially for wood in service, brown rot leads to great problems (Zabel and Morrell, 1992). The reason for this is that brown rot fungi can cause massive strength loss even at low mass loss (Cowling 1961, Filley et al. 2002, Niemenmaa et al. 2008, Arantes et al. 2012, Arantes and Goodell 2014). Decay tests with model brown rot fungi (for example Gloeophyllum trabeum and Rhodonia placenta) are used for testing new and existing wood protection systems.
The current hypothesis is, that brown rot fungi degrade wood in two steps; oxidative processes followed by enzymatic hydroltic activities (Baldrian and Valášková 2008, Arantes et al. 2012, Arantes and Goodell 2014).
Previous studies have shown that the comparison of gene expression gives insight into fungal degradation mechanisms, when growing on untreated wood, compared to modified wood (Alfredsen and Pilgård 2014, Ringman et al. 2014, Alfredsen et al. 2016, Ringman et al. 2016). Difficulties have however been seen regarding the differentiation of the oxidative and the enzymatic degradation phase since the sample design was not capable of separating those two.
Zhang et al. showed in 2016 that the two decay mechanisms are in fact spatially segregated, therefor they suggested a new test design (wood wafer method), where the initial decay phase is better represented. In this study we tested the wood wafer method on untreated and acetylated wood. This paper discusses advantages and disadvantages of the wood wafer method, compared to the traditional miniblock test (Bravery 1979) for decay tests to be used for further molecular and biochemical analysis.
Keywords: brown rot fungi, wood modification, gene expression
Authors
Martina Kölle
TU München, Holzforschung München
Annica Pilgård
Rebecka Ringman
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