Department for Animal Evolution and Biodiversity, Johann-Friedrich-Blumenbach-Institut für Zoologie und Anthropologie, Georg-August-Universität Göttingen, Untere Karspüle 2, 37073 Göttingen, Germany.
Infect Genet Evol. 2024 Sep;123:105641. doi: 10.1016/j.meegid.2024.105641. Epub 2024 Jul 14.
Endosymbiotic Alphaproteobacteria of the genus Wolbachia are exclusively transferred maternally from mother to offspring, but horizontal transfer across species boundaries seems to be frequent as well. However, the (ecological) mechanisms of how these bacteria are transferred between distantly related arthropod hosts remain unclear. Based on the observation that species that are part of the same ecological community often also share similar Wolbachia strains, host ecology has been hypothesized as an important factor enabling transmission and a key factor in explaining the global distribution of Wolbachia lineages. In this study, we focus on the diversity and abundance of Wolbachia strains in soil arthropods, a so far rather neglected community. We screened 82 arthropod morphotypes collected in the beech forest (dominated by Fagus sp.) soil in the area of Göttingen in central Germany for the presence of Wolbachia. By performing a PCR screen with Wolbachia-MLST markers (coxA, dnaA, fbpA, ftsZ, gatB, and hcpA), we found a rather low infection frequency of 12,2%. Additionally, we performed metagenomic screening of pooled individuals from the same sampling site and could not find evidence that this low infection frequency is an artefact due to PCR-primer bias. Phylogenetic analyses of the recovered Wolbachia strains grouped them in three known supergroups (A, B, and E), with the first report of Wolbachia in Protura (Hexapoda). Moreover, Wolbachia sequences from the pseudoscorpion Neobisium carcinoides cluster outside the currently known supergroup diversity. Our screening supports results from previous studies that the prevalence of Wolbachia infections seems to be lower in soil habitats than in above-ground terrestrial habitats. The reasons for this pattern are not completely understood but might stem from the low opportunity of physical contact and the prevalence of supergroups that are less suited for horizontal transfer.
内共生的α变形菌属沃尔巴克氏体完全通过母系从母亲传递给后代，但种间的水平转移似乎也很频繁。然而，这些细菌在亲缘关系较远的节肢动物宿主之间转移的（生态）机制仍不清楚。基于这样的观察，即属于同一生态群落的物种通常也共享相似的沃尔巴克氏体菌株，宿主生态学被假设为促进传播的一个重要因素，也是解释沃尔巴克氏体谱系全球分布的关键因素。在这项研究中，我们专注于土壤节肢动物中沃尔巴克氏体菌株的多样性和丰度，这是一个迄今为止被忽视的群落。我们筛选了在德国中部哥廷根地区山毛榉林（以山毛榉属为主）土壤中收集的 82 个节肢动物形态型，以检测沃尔巴克氏体的存在。通过使用沃尔巴克氏体-MLST 标记（coxA、dnaA、fbpA、ftsZ、gatB 和 hcpA）进行 PCR 筛选，我们发现感染频率相当低，为 12.2%。此外，我们对来自同一采样点的个体进行了元基因组筛选，没有发现证据表明这种低感染频率是由于 PCR 引物偏倚造成的假象。回收的沃尔巴克氏体菌株的系统发育分析将它们分为三个已知的超级群（A、B 和 E），这是首次在原尾目（六足动物）中发现沃尔巴克氏体。此外，来自伪蝎 Neobisium carcinoides 的沃尔巴克氏体序列聚类在目前已知的超级群多样性之外。我们的筛选结果支持了先前研究的结果，即在土壤生境中，沃尔巴克氏体感染的流行率似乎低于地上陆地生境。这种模式的原因尚不完全清楚，但可能源于物理接触的机会较少，以及不适合水平转移的超级群的流行。
