Use of the Internal Transcribed Spacer (ITS) Regions to Examine Symbiont Divergence and as a Diagnostic Tool for Sodalis-Related Bacteria.
Use of the Internal Transcribed Spacer (ITS) Regions to Examine Symbiont Divergence and as a Diagnostic Tool for Sodalis-Related Bacteria.
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DOI：
10.3390/insects2040515
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发表时间：
2011-11-30
期刊：
影响因子：
3
通讯作者：
Rio RV
中科院分区：
文献类型：
--
作者：
Snyder AK;Adkins KZ;Rio RV
细菌在大多数生态位中表现出色，包括昆虫共生。在广泛的昆虫中建立的一组细菌共生体，与采采蝇（双翅目：舌蝇科）的次生共生体 Sodalis glsinidius 具有高度的 16S rRNA 相似性。尽管 16S rRNA 已被证明可以为该分支的表征提供信息，但由于选择性限制，该基因不足以检查最近的分歧。在这里，我们评估了内部转录间隔区 (ITS) 区域的应用，特别是 ITSglu 和 ITSala,ile，与 16S rRNA 结合使用以增强 Sodalis 相关细菌的系统发育分辨率。 Sodalis 和相关细菌的 16S rRNA + ITS 区域表现出显着差异，并且对于系统发育解析具有稳健性。与其他肠杆菌科不同，从采采菌中分离出来的 Sodalis 的单系进化枝一直被观察到，这表明由于宿主适应而出现多样化。相比之下，从河马蝇和各种半翅目和鞘翅目中分离出的共生体的系统发育分布相互交织，表明要么是水平转移，要么是最近从环境来源建立的。还观察到 Sodalis 相关细菌的谱系分裂为共生和自由生活的姐妹群。此外，我们建议将 ITS 区域作为诊断标记，用于识别现场中其他与 Sodalis 相关的共生体。这些结果扩展了我们对信息丰富的基因组区域的了解，以评估自最后一个共同祖先分裂以来的遗传分歧，这种多功能的昆虫共生进化枝已越来越被认为对我们理解共生进化有价值。这些兼性和最近相关的共生体可能提供适应不同宿主背景所遇到的动态生态的新特征来源。
Bacteria excel in most ecological niches, including insect symbioses. A cluster of bacterial symbionts, established within a broad range of insects, share high 16S rRNA similarities with the secondary symbiont of the tsetse fly (Diptera: Glossinidae), Sodalis glossinidius. Although 16S rRNA has proven informative towards characterization of this clade, the gene is insufficient for examining recent divergence due to selective constraints. Here, we assess the application of the internal transcribed spacer (ITS) regions, specifically the ITSglu and ITSala,ile, used in conjunction with 16S rRNA to enhance the phylogenetic resolution of Sodalis-allied bacteria. The 16S rRNA + ITS regions of Sodalis and allied bacteria demonstrated significant divergence and were robust towards phylogenetic resolution. A monophyletic clade of Sodalis isolates from tsetse species, distinct from other Enterobacteriaceae, was consistently observed suggesting diversification due to host adaptation. In contrast, the phylogenetic distribution of symbionts isolated from hippoboscid flies and various Hemiptera and Coleoptera were intertwined suggesting either horizontal transfer or a recent establishment from an environmental source. Lineage splitting of Sodalis-allied bacteria into symbiotic and free-living sister groups was also observed. Additionally, we propose an ITS region as a diagnostic marker for the identification of additional Sodalis-allied symbionts in the field. These results expand our knowledge of informative genome regions to assess genetic divergence since splitting from the last common ancestor, of this versatile insect symbiont clade that have become increasingly recognized as valuable towards our understanding of the evolution of symbiosis. These facultative and recently associated symbionts may provide a novel source of traits adaptable to the dynamic ecologies encountered by diverse host backgrounds.