Khokon Anis Mahmud, Schneider Dominik, Daniel Rolf, Polle Andrea
Department of Forest Botany and Tree Physiology, University of Göttingen, 37077 Göttingen, Germany.
Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany.
Microorganisms. 2021 Oct 11;9(10):2131. doi: 10.3390/microorganisms9102131.
Ectomycorrhizal and saprotrophic fungi play pivotal roles in ecosystem functioning. Here, we studied the vertical differentiation of root-associated fungi (RAF) in temperate forests. We analysed RAF assemblages in the organic and mineral soil from 150 experimental forest plots across three biogeographic regions spanning a distance of about 800 km. Saprotrophic RAF showed the highest richness in organic and symbiotrophic RAF in mineral soil. Symbiotrophic RAF exhibited higher relative abundances than saprotrophic fungi in both soil layers. Beta-diversity of RAF was mainly due to turnover between organic and mineral soil and showed regional differences for symbiotrophic and saprotrophic fungi. Regional differences were also found for different phylogenetic levels, i.e., fungal orders and indicator species in the organic and mineral soil, supporting that habitat conditions strongly influence differentiation of RAF assemblages. Important exceptions were fungal orders that occurred irrespective of the habitat conditions in distinct soil layers across the biogeographic gradient: Russulales and Cantharellales (ectomycorrhizal fungi) were enriched in RAF assemblages in mineral soil, whereas saprotrophic Polyporales and Sordariales and ectomycorrhizal Boletales were enriched in RAF assemblages in the organic layer. These results underpin a phylogenetic signature for niche partitioning at the rank of fungal orders and suggest that RAF assembly entails two strategies encompassing flexible and territorial habitat colonization by different fungal taxa.
外生菌根真菌和腐生真菌在生态系统功能中发挥着关键作用。在此，我们研究了温带森林中与根相关真菌（RAF）的垂直分化。我们分析了跨越约800公里的三个生物地理区域的150个实验林地的有机土壤和矿质土壤中的RAF组合。腐生RAF在有机土壤中物种丰富度最高，而共生RAF在矿质土壤中物种丰富度最高。在两个土壤层中，共生RAF的相对丰度均高于腐生真菌。RAF的β多样性主要源于有机土壤和矿质土壤之间的更替，并且共生真菌和腐生真菌表现出区域差异。在不同的系统发育水平上，即在有机土壤和矿质土壤中的真菌目和指示物种方面也发现了区域差异，这支持了栖息地条件强烈影响RAF组合的分化。重要的例外是在生物地理梯度上不同土壤层中无论栖息地条件如何都会出现的真菌目：红菇目和鸡油菌目（外生菌根真菌）在矿质土壤的RAF组合中富集，而腐生的多孔菌目和粪壳菌目以及外生菌根的牛肝菌目在有机层的RAF组合中富集。这些结果为真菌目水平上的生态位划分提供了系统发育特征，并表明RAF的组装涉及两种策略，即不同真菌类群对栖息地的灵活定殖和区域定殖。
