Evidence for low-titre infections in insect symbiosis: Wolbachia in the bark beetle Pityogenes chalcographus (Coleoptera, Scolytinae)
Evidence for low-titre infections in insect symbiosis: Wolbachia in the bark beetle Pityogenes chalcographus (Coleoptera, Scolytinae)
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DOI：
10.1111/j.1462-2920.2009.01914.x
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发表时间：
2009-08-01
影响因子：
5.1
通讯作者：
Stauffer, Christian
中科院分区：
文献类型：
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作者：
Arthofer, Wolfgang;Riegler, Markus;Stauffer, Christian
Wolbachia是许多昆虫物种中发现的强制性内共生α -变形菌。它们是母系传播的，通常表现出细胞质不相容等生殖表型。松皮蛾是一种严重危害云杉林的树皮甲虫。它的欧洲种群被部分交叉屏障分隔成几个线粒体分支。在这项研究中，我们使用高度敏感的巢式PCR技术测试了覆盖欧洲甲虫自然范围的大量样本集，以确定沃尔巴克氏体的存在以及感染模式与有丝分裂型之间的关系。35.5%的个体感染了内共生菌，鉴定出两种不同的菌株。这两种菌株的滴度都很低，常规检测方法无法检测到。这种感染在整个欧洲都存在，不太可能在宿主体内造成部分交叉障碍，也不太可能与线粒体进化枝分离。这种模式表明种群向内共生丧失和沃尔巴克氏体的重复种内水平转移的方向进化。另外，在P. chalcographus中发现的低滴度感染是沃尔巴克氏体在宿主物种中以低密度和低频率持续存在的另一个例子。
P>Wolbachia are obligatory endosymbiotic alpha-proteobacteria found in many insect species. They are maternally transmitted and often exhibit reproductive phenotypes like cytoplasmic incompatibility. Pityogenes chalcographus is a bark beetle causing severe damage in spruce stands. Its European populations are divided into several mitochondrial clades separated by partial crossing barriers. In this study, we tested a large sample set covering the natural range of the beetle in Europe for the presence of Wolbachia and associations between infection pattern and mitotypes using a highly sensitive nested PCR technique. 35.5% of the individuals were infected with the endosymbiont and two distinct strains were identified. Both strains occur in low titre not accessible by conventional detection methods. The infections are present all over Europe, unlikely to cause the partial crossing barriers in this host and uncoupled from mitochondrial clades. This pattern is indicative for populations evolving towards endosymbiont loss and for repeated intraspecific horizontal transfer of Wolbachia. Alternatively, the low-titre infections found in P. chalcographus are yet another example for Wolbachia that can persist in host species at low densities and frequencies.