Table_1_Explorative Meta-Analysis of 377 Extant Fungal Genomes Predicted a Total Mycobiome Functionality of 42.4 Million KEGG Functions.xlsx

Unveiling the relationship between taxonomy and function of the microbiome is crucial to determine its contribution to ecosystem functioning. However, while there is a considerable amount of information on microbial taxonomic diversity, our understanding of its relationship to functional diversity is still scarce. Here, we used a meta-analysis of completely annotated extant genomes of 377 taxonomically distinct fungal species to predict the total fungal microbiome functionality on Earth with accumulation curves (ACs) of all known functions from the level 3 of KEGG Orthology using both parametric and non-parametric estimates in an explorative data-mining approach. The unsaturated model extrapolating functional diversity as a function of species richness described the ACs significantly better than the saturated model that assumed a limited total number of functions, which suggested the presence of widespread and rare functions. Based on previous estimates of 3.8 million fungal species on Earth, we propagated the unsaturated model to predict a total of 42.4 ± 0.5 million KEGG level 3 functions of which only 0.06% are known today. Our approach not only highlights the presence of widespread and rare functions but points toward the necessity of novel and more sophisticated methods to unveil the entirety of functions to fully understand the involvement of the fungal microbiome in ecosystem functioning.

揭示微生物组的分类学特征与功能之间的关联，对于明确其对生态系统功能的贡献至关重要。然而，尽管当前已积累了大量关于微生物分类多样性的研究数据，但我们对其与功能多样性之间关联的认知仍较为匮乏。本研究针对377个分类学特征各异的真菌物种的完整注释现存基因组开展元分析，采用探索性数据挖掘方法，结合参数化与非参数化两种估计方式，借助KEGG直系同源（KEGG Orthology）三级层级的全部已知功能条目构建累积曲线（accumulation curves, ACs），以此预测全球真菌微生物组的整体功能谱。将功能多样性作为物种丰富度的函数进行外推的不饱和模型，对累积曲线的拟合效果显著优于假定功能总数有限的饱和模型，这一结果暗示了广泛存在且稀有功能类群的存在。基于此前全球真菌物种总量为380万的估算，我们运用该不饱和模型进行外推，预测全球真菌微生物组的KEGG三级功能总数可达4240±50万个，而目前仅探明其中0.06%的功能。本研究方法不仅证实了广泛存在且稀有功能的存在，同时也表明亟需开发新颖且更为精细的研究手段，以揭示全部真菌功能的全貌，从而全面理解真菌微生物组在生态系统功能中所发挥的作用。