Gruwell Matthew E, Morse Geoffrey E, Normark Benjamin B
Department of Plant, Soil, and Insect Sciences, Graduate Program in Organismic and Evolutionary Biology, Fernald Hall, University of Massachusetts, Amherst, MA 01003, USA.
Mol Phylogenet Evol. 2007 Jul;44(1):267-80. doi: 10.1016/j.ympev.2007.01.014. Epub 2007 Feb 15.
Insects in the sap-sucking hemipteran suborder Sternorrhyncha typically harbor maternally transmitted bacteria housed in a specialized organ, the bacteriome. In three of the four superfamilies of Sternorrhyncha (Aphidoidea, Aleyrodoidea, Psylloidea), the bacteriome-associated (primary) bacterial lineage is from the class Gammaproteobacteria (phylum Proteobacteria). The fourth superfamily, Coccoidea (scale insects), has a diverse array of bacterial endosymbionts whose affinities are largely unexplored. We have amplified fragments of two bacterial ribosomal genes from each of 68 species of armored scale insects (Diaspididae). In spite of initially using primers designed for Gammaproteobacteria, we consistently amplified sequences from a different bacterial phylum: Bacteroidetes. We use these sequences (16S and 23S, 2105 total base pairs), along with previously published sequences from the armored scale hosts (elongation factor 1alpha and 28S rDNA) to investigate phylogenetic congruence between the two clades. The Bayesian tree for the bacteria is roughly congruent with that of the hosts, with 67% of nodes identical. Partition homogeneity tests found no significant difference between the host and bacterial data sets. Of thirteen Shimodaira-Hasegawa tests, comparing the original Bayesian bacterial tree to bacterial trees with incongruent clades forced to match the host tree, 12 found no significant difference. A significant difference in topology was found only when the entire host tree was compared with the entire bacterial tree. For the bacterial data set, the treelengths of the most parsimonious host trees are only 1.8-2.4% longer than that of the most parsimonious bacterial trees. The high level of congruence between the topologies indicates that these Bacteroidetes are the primary endosymbionts of armored scale insects. To investigate the phylogenetic affinities of these endosymbionts, we aligned some of their 16S rDNA sequences with other known Bacteroidetes endosymbionts and with other similar sequences identified by BLAST searches. Although the endosymbionts of armored scales are only distantly related to the endosymbionts of the other sternorrhynchan insects, they are closely related to bacteria associated with eriococcid and margarodid scale insects, to cockroach and auchenorrynchan endosymbionts (Blattabacterium and Sulcia), and to male-killing endosymbionts of ladybird beetles. We propose the name "Candidatus Uzinura diaspidicola" for the primary endosymbionts of armored scale insects.
吸食树液的半翅目胸喙亚目昆虫通常在一个特殊器官——菌体内携带着母系传播的细菌。在胸喙亚目的四个总科中，有三个总科（蚜总科、粉虱总科、木虱总科）中，与菌体相关的（主要）细菌谱系来自γ-变形菌纲（变形菌门）。第四个总科，蚧总科（介壳虫），有各种各样的细菌内共生体，其亲缘关系在很大程度上尚未得到探索。我们从68种盾蚧科（ armored scale insects）昆虫中分别扩增了两个细菌核糖体基因的片段。尽管最初使用的是为γ-变形菌设计的引物，但我们始终扩增出了来自另一个细菌门的序列：拟杆菌门。我们使用这些序列（16S和23S，共2105个碱基对），以及之前发表的盾蚧宿主的序列（延伸因子1α和28S rDNA）来研究两个进化枝之间的系统发育一致性。细菌的贝叶斯树与宿主的大致一致，67%的节点相同。分区同质性检验发现宿主和细菌数据集之间没有显著差异。在13次Shimodaira-Hasegawa检验中，将原始的贝叶斯细菌树与将不一致的进化枝强制与宿主树匹配的细菌树进行比较，有12次没有发现显著差异。只有当将整个宿主树与整个细菌树进行比较时，才发现拓扑结构存在显著差异。对于细菌数据集，最简约的宿主树的树长仅比最简约的细菌树长1.8 - 2.4%。拓扑结构之间的高度一致性表明这些拟杆菌是盾蚧科昆虫的主要内共生体。为了研究这些内共生体的系统发育亲缘关系，我们将它们的一些16S rDNA序列与其他已知的拟杆菌内共生体以及通过BLAST搜索鉴定的其他相似序列进行了比对。尽管盾蚧的内共生体与其他胸喙亚目昆虫的内共生体关系较远，但它们与绵蚧科和珠蚧科昆虫相关的细菌、蟑螂和颈喙亚目昆虫的内共生体（Blattabacterium和Sulcia）以及瓢虫的杀雄内共生体密切相关。我们为盾蚧科昆虫的主要内共生体提出了“Candidatus Uzinura diaspidicola”这个名称。
