Fungal community composition associated with the agarwood-producing tree, Aquilaria sinensis

Agarwood, a precious and rare resin, is primarily produced by Aquilaria sinensis of the plant family Thymelaeaceae. The fungi associated with Aquilaria are a rich source of secondary metabolites, demonstrating an exciting potential for drug discovery. However, despite its significance, there is a lack of comparative analysis of the fungal communities associated with different plant parts of A. sinensis and in different regions. In this study, we collected A. sinensis samples (agarwood resin, dead branches, healthy branches, and healthy leaves) from Maoming and Zhanjiang in Guangdong Province and Xishuangbanna and Yuanjiang in Yunnan Province, China. A total of 960 strains belonging to 64 genera of 44 families were successfully isolated. Among them, 142 strains had been previously reported in articles by our research team and were included in this study for community analysis. Based on a Venn diagram, the study revealed recombination relationships among fungal communities from plant parts and different collection sites. In addition, this study introduces new taxa belonging to the genera Banksiophoma, Deniquelata, Fomitiporia, and Montagnula, thereby enhancing our knowledge of the known fungal diversity in Aquilaria sinensis. At the same time, relevant notes on 64 genera are summarized, and their ecological functions, distribution, and relationships with Aquilaria spp. are discussed. For example, Fusarium is often reported to have the potential to induce the production of agarwood, providing valuable literature for further research. Overall, this study greatly enriches knowledge on the diversity of fungi associated with Aquilaria, providing potential "candidate fungal inducers", and lays a foundation for further exploring the ecological functions of agarwood and its associated fungi. Additionally, to avoid conceptual confusion, this study proposes that identifying fungi isolated from agarwood resin as 'agarwood-associated fungi', differentiating them from endophytic fungi in healthy tissues. This distinction is vital as it helps to clarify the ecological roles and origins of the fungi involved in agarwood formation. This study also underscores the need for more targeted research on their potential functions in agarwood resin production.