Interkingdom and intrakingdom interactions in the microbiome of Heterobasidion fruiting body and associated decayed woody tissues

The Heterobasidion annosum species complex is a major threat to the forest industry in the northern temperate regions of the world. The fungal and bacterial biota communities in Heterobasidion-infected trees have been extensively studied, but less is known about the interkingdom and intrakingdom interactions among the microbiome. The bacteria-fungi interkingdom analysis has revealed significant findings compared to the intrakingdom analysis in recent studies. In this study, we aimed to (i) unravel the contribution and development of the bacteria and other fungi in the Heterobasidion-infected wood decay process; (ii) uncover how environmental factors and the conifer pathogen drive the microbiome community structure and function changes; and (iii) identify the core microbiome during the Heterobasidion-mediated wood decay process. Internal transcribed spacer and 16S amplicon sequencing data from the Heterobasidion fruiting body and its associated woody tissue were applied in this analysis. Samples collected from managed forest and nature reserve forest were classified into four decay classes based on the extent of decay of the wood. Our result showed that bacteria and fungi have different abundances and activities in both study materials. The Heterobasidion ecological correlation network is conserved, especially in the fruiting body. The core microbiome defined in our analysis showed huge potential for the microbiome community's functioning. A particular Heterobasidion Operational Taxonomic Units (OTU) had the most important impact on the community and disease development. Forest management has the biggest impact on the microbiome assembly, and the fungal community is more sensitive to environmental changes.