Lichen thalli harbor complex fungal communities (mycobiomes) of species with divergent trophic and ecological strategies. The complexity and diversity of lichen mycobiomes are still largely unknown, despite surveys combining culture-based methods and high-throughput sequencing (HTS). The results of such surveys are strongly influenced by the barcode locus chosen, its sensitivity in discriminating taxa, and the depth to which public sequence repositories cover the phylogenetic spectrum of fungi. Here, we use HTS of the internal transcribed spacer 2 (ITS2) to assess the taxonomic composition and diversity of a well-characterized, alpine rock lichen community that includes thalli symptomatically infected by lichenicolous fungi as well as asymptomatic thalli. Taxa belonging to the order Chaetothyriales are the major components of the observed lichen mycobiomes. We predict sequences representative of lichenicolous fungi characterized morphologically and assess their asymptomatic presence in lichen thalli. We demonstrated the limitations of metabarcoding in fungi and show how the estimation of species diversity widely differs when ITS1 or ITS2 are used as barcode, and particularly biases the detection of Basidiomycota. The complementary analysis of both ITS1 and ITS2 loci is therefore required to reliably estimate the diversity of lichen mycobiomes.

中文翻译：

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ITS2 元条形码分析补充了地衣菌群多样性数据。

地衣菌体拥有复杂的真菌群落（真菌群落），其物种具有不同的营养和生态策略。尽管结合了基于培养的方法和高通量测序（HTS）的调查，但地衣菌群的复杂性和多样性在很大程度上仍然未知。此类调查的结果受到所选择的条形码位点、其区分分类单元的敏感性以及公共序列存储库覆盖真菌系统发育谱的深度的强烈影响。在这里，我们使用内部转录间隔区 2 (ITS2) 的 HTS 来评估特征明确的高山岩石地衣群落的分类组成和多样性，该群落包括有症状的地衣真菌感染的菌体以及无症状的菌体。属于毛藻目的类群是观察到的地衣真菌生物群的主要组成部分。我们预测了代表地衣真菌形态特征的序列，并评估了它们在地衣菌体中的无症状存在。我们证明了真菌中元条形码的局限性，并展示了当 ITS1 或 ITS2 用作条形码时，物种多样性的估计存在很大差异，特别是对担子菌门的检测产生偏差。因此，需要对 ITS1 和 ITS2 位点进行互补分析，以可靠地估计地衣真菌组的多样性。