Abstract
Brown rot fungi are known to be a major wood rotting fungi against wooden buildings in Japan because they cause the significant loss of wood strength in the incipient stages of decay. Therefore, it is essential to gain an understanding of the detailed mechanisms by which they degrade wood. Unlike white rot fungi, which possess a complete enzymatic system of wood degradation, that in brown rot fungi is generally believed to involve a non-enzymatic degradation system followed by enzymatic degradation, whereas the detailed mechanisms of this process remain unclear. To clarify the enzymatic wood degradation mechanism employed by wood rotting fungi, it is crucial to investigate the regulatory mechanisms governing enzyme production. While the relationship between carbon sources and enzyme production in white rot fungi has been extensively studied, there is a scarcity of research on brown rot fungi, leaving many aspects unexplored. In this study, we explored how the genes encoding major enzyme involved in the degradation of wood cell wall polysaccharide in Gloeophyllum trabeum , one of model brown rot fungi, respond to different carbon sources. We found that cellulase gene expression was induced in the presence of cellulose, similar to white rot fungi. Additionally, we observed diverse gene expression patterns for xylanase genes and lytic polysaccharide monooxygenase genes. Regarding the effect of the addition of soluble sugars, on the other hand, some cellulase genes were induced in cellobiose medium while others were not. Similar behavior was observed in the case of xylanase genes and lytic polysaccharide monooxygenase genes, with each gene exhibiting distinct patterns of expression in response to the added sugars.
