Project description:AIM: By adopting comparative transcriptomic approach, we investigated the gene expression of wood decomposing Basidiomycota fungus Phlebia radiata. Our aim was to reveal how hypoxia and lignocellulose structure affect primary metabolism and the expression of wood decomposition related genes. RESULTS: Hypoxia was a major regulator for intracellular metabolism and extracellular enzymatic degradation of wood polysaccharides by the fungus. Our results manifest how oxygen depletion affects not only over 200 genes of fungal primary metabolism but also plays central role in regulation of secreted CAZyme (carbohydrate-active enzyme) encoding genes. Based on these findings, we present a hypoxia-response mechanism in wood-decaying fungi divergent from the regulation described for Ascomycota fermenting yeasts and animal-pathogenic species of Basidiomycota.
Project description:Deadwood plays a crucial role in forest ecosystems, but we have limited information about the specific fungal taxa and extracellular lignocellulolytic enzymes that are actively involved in the decomposition process in situ. To investigate this, we studied the fungal metaproteome of twelve deadwood tree species in a replicated, eight-year experiment. Key fungi observed included genera of white-rot fungi (Basidiomycota, e.g. Armillaria, Hypholoma, Mycena, Ischnoderma, Resinicium), brown-rot fungi (Basidiomycota, e.g. Fomitopsis, Antrodia), diverse Ascomycota including xylariacous soft-rot fungi (e.g. Xylaria, Annulohypoxylon, Nemania) and various wood-associated endophytes and saprotrophs (Ascocoryne, Trichoderma, Talaromyces). These fungi used a whole range of extracellular lignocellulolytic enzymes, such as peroxidases, peroxide-producing enzymes, laccases, cellulases, glucosidases, hemicellulases (xylanases) and lytic polysaccharide monooxygenases (LPMOs). Both the fungi and enzymes were tree-specific, with specialists and generalists being distinguished by network analysis. The extracellular enzymatic system was highly redundant, with many enzyme classes of different origins present simultaneously in all decaying logs. Strong correlations were found between peroxide-producing enzymes (oxidases) and peroxidases as well as LPMOs, and between ligninolytic, cellulolytic and hemicellulolytic enzymes. The overall protein abundance of lignocellulolytic enzymes was reduced by up to -30% in gymnosperm logs compared to angiosperm logs, and gymnosperms lacked ascomycetous enzymes, which may have contributed to the lower decomposition of gymnosperm wood. In summary, we have obtained a comprehensive and detailed insight into the enzymatic machinery of wood-inhabiting fungi in several temperate forest tree species, which can help to improve our understanding of the complex ecological processes in forest ecosystems.
Project description:Agaricomycetes produce the most efficient enzyme systems to degrade wood and the most complex morphological structures in the fungal kingdom. Despite decades-long interest in their genetic bases, the evolution and functional diversity of both wood-decay and fruiting body formation are incompletely known.Here, we perform comparative genomic and transcriptomic analyses of wood-decay and fruiting body development in Auriculariopsis ampla and Schizophyllum commune (Schizophyllaceae), species with secondarily simplified morphologies and enigmatic wood-decay strategy and weak pathogenicity to woody plants. The plant cell wall degrading enzyme repertoires of Schizophyllaceae are transitional between those of white rot species and less efficient wood-degraders such as brown rot or mycorrhizal fungi. Rich repertoires of suberinase and tannase genes were found in both species, with tannases restricted to Agaricomycetes that preferentially colonize bark-covered wood, suggesting potential complementation of their weaker wood-decaying abilities and adaptations to wood colonization through the bark. Fruiting body transcriptomes of A. ampla and S. commune revealed a high rate of divergence in developmental gene expression, but also several genes with conserved developmental expression, including novel transcription factors and small-secreted proteins, some of the latter might represent fruiting body effectors. Taken together, our analyses highlighted novel aspects of wood-decay and fruiting body development in a widely distributed family of mushroom-forming fungi.