Molecular phylogenetic analysis of Wolbachia infection in the Ostrinia furnacalis species group

对4个Ostrinia种（O. furnacalis、O. scapulalis、O. orientalis和O. zagulievi）共20多只感染了Wolbachia的个体进行了2个Wolbachia基因（ftsZ和wsp）的DNA序列测定。这些样本的两种基因序列相同，这表明在这四种飞蛾中感染的沃尔巴克氏菌菌株是相同的或彼此非常密切相关。线粒体COII基因的DNA序列被确定为在四种宿主物种中共有35例沃尔巴克氏体感染，在祖先中具有相同的单一感染事件。此外，对4种Ostrinia、O. zealis、O. nublialis和O. sp等7种共200余个个体的COII基因进行了测序。所有COII序列的系统发育分析表明，沃尔巴克氏体相关COII序列不属于7种主要的线粒体系统群。这表明沃尔巴克氏体相关的COII谱系在O. furnacalis物种群中具有非常古老的起源。基于这些发现，我得出结论，沃尔巴克氏体感染通过与福纳恰氏体O. furnacalis物种群中的宿主杂交扩大了其宿主范围。根据目前的研究结果，无法确定将沃尔巴克氏体感染提供给其他宿主物种的源物种。沃尔巴克氏体感染的进化起源最有可能追溯到宿主物种形成事件之前。

DNA sequences for two Wolbachia genes (ftsZ and wsp) were determined for more than 20, in total, Wolbachia-infected individuals of four Ostrinia species (O. furnacalis, O. scapulalis, O. orientalis and O. zaguliaevi). These samples shared identical sequences for both genes, suggesting that Wolbachia strains infected in the four moth species are identical or very closely related to each other.DNA sequences for the mitochondrial COII gene were determined for a total of 35 Wolbachia-infected infections in the four host species share the same, single infection event in ancestry. Besides the COII gene was sequenced for a total of more than 200 individuals of seven species including the four Ostrinia species, O. zealis, O. nublialis and O. sp. Phylogenetic analysis of all the COII sequences showed that the Wolbachia-associated COII sequences do not belong to major mitochondrial phylogroups in the seven species. This suggests that the Wolbachia-associated COII lineage has a very old origin in the O. furnacalis species group.Based on the findings, I concluded that the Wolbachia infection has expanded its host range through hybridization of hosts in the O. furnacalis species group. The source species which has supplied the Wolbachia infection to other host species could not be specified from the present findings. The evolutionary origin of Wolbachia infection in the O. furnacalis group is most likely to date back older than speciation events of hosts.