Data_Sheet_3_Mycobiomes of Young Beech Trees Are Distinguished by Organ Rather Than by Habitat, and Community Analyses Suggest Competitive Interactions Among Twig Fungi.docx

Beech trees (Fagus sylvatica) are prominent keystone species of great economic and environmental value for central Europe, hosting a diverse mycobiome. The composition of endophyte communities may depend on tree health, plant organ or tissue, and growth habitat. To evaluate mycobiome communalities at local scales, buds, and twigs were sampled from two young healthy mountain beech stands in Bavaria, Germany, four kilometers apart. With Illumina high-throughput sequencing, we found 113 fungal taxa from 0.7 million high-quality reads that mainly consisted of Ascomycota (52%) and Basidiomycota (26%) taxa. Significant correlations between richness and diversity indices were observed (p < 0.05), and mycobiomes did not differ between habitats in the current study. Species richness and diversity were higher in twigs compared to spring buds, and the assemblages in twigs shared most similarities. Interaction network analyses revealed that twig-bound fungi shared similar numbers of (interaction) links with others, dominated by negative co-occurrences, suggesting that competitive exclusion may be the predominant ecological interaction in the highly connected twig mycobiome. Combining community and network analyses strengthened the evidence that plant organs may filter endophytic communities directly through colonization access and indirectly by facilitating competitive interactions between the fungi.

欧洲山毛榉（Fagus sylvatica）是中欧地区兼具重要经济与生态价值的关键种，其宿主拥有多样的真菌组（mycobiome）。内生真菌群落的组成可能受树木健康状况、植物器官或组织以及生长生境的调控。为探究局域尺度下的真菌组群落共性，研究人员从德国巴伐利亚州两处相距4公里的健康年轻山毛榉林分中采集了芽与细枝样本。通过Illumina高通量测序，从70万条优质读段中鉴定得到113个真菌类群，其中子囊菌门（Ascomycota）与担子菌门（Basidiomycota）类群分别占比52%与26%。本研究发现丰富度与多样性指数间存在显著相关性（p < 0.05），且不同生境的真菌组并无显著差异。细枝中的物种丰富度与多样性均高于春季芽，细枝内的真菌群落组成相似度最高。互作网络分析显示，定殖于细枝的真菌与其他类群的互作链接数目相近，且以负共现关系为主，这表明竞争排除作用可能是该高连接度细枝真菌组中占主导的生态互作方式。结合群落与网络分析的结果进一步证实，植物器官可通过两种方式筛选内生真菌群落：直接通过定殖途径进行筛选，以及间接介导真菌间的竞争互作。