Oxidative stress impacts carbon metabolism and induces upregulation of redox enzymes andsmall secreted proteins in the wood-decay fungus.

backgroundFungi live in diverse environments requiring tolerance against abiotic and biotic stress and changing atmospheric conditions. Studies with white rot and brown rot species of Polyporales Basidiomycota have demonstrated that aerobic wood decay fungi may adapt to low oxygen and even anoxic conditions, which they undoubtedly encounter in their deadwood habitat. In the white rot fungus Phlebia radiata, oxygen depletion on lignocellulose substrates leads to hypoxia and fermentative metabolism. In this study, we elaborated the atmospheric effect further by subjecting the fungus to oxidative stress on wood substrate under aerobic and low oxygen conditions, with the aim to examine changes in gene expression and metabolic pathways as consequences of the oxidative treatment.

resultsOverall, 762 genes were significantly differentially expressed (DEGs with absolute Log

conclusionsOxidative stress caused a substantial change in fungal gene expression, but with different responses depending on the culture atmosphere. This may be explained by contrasting fungal metabolic states before the shock as was observed in extracellular enzyme, aromatic metabolite and redox activity profiles. Surprisingly, oxidative shock caused downregulation of a few heat-shock proteins whereas small secreted proteins were either up- or downregulated, suggesting both sensing and regulative roles for these, functionally yet unknown, diverse fungal proteins.