Evidence of Environmental and Vertical Transmission of Burkholderia Symbionts in the Oriental Chinch Bug, Cavelerius saccharivorus (Heteroptera: Blissidae)
Evidence of Environmental and Vertical Transmission of Burkholderia Symbionts in the Oriental Chinch Bug, Cavelerius saccharivorus (Heteroptera: Blissidae)
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DOI：
10.1128/aem.01087-14
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发表时间：
2014-10-01
影响因子：
4.4
通讯作者：
Kikuchi, Yoshitomo
中科院分区：
文献类型：
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作者：
Itoh, Hideomi;Aita, Manabu;Kikuchi, Yoshitomo
共生微生物的垂直传播在昆虫中无处不在，但其进化过程尚不清楚。甘蔗小食心虫Cavelerius seccharvorus(异翅目：小食心虫科)是一种严重的甘蔗害虫，其发育的大量管状中肠隐窝中密集分布着共生细菌。16S rRNA基因的克隆和序列分析表明，该隐窝由属于贝塔蛋白细菌属伯克霍尔德氏菌的一组特定细菌主导。伯克霍尔德氏菌的序列被分为三个不同的分支：洋葱伯克霍尔德氏菌复合体(BCC)、植物相关的有益和环境组(PBE)和臭虫相关的有益和环境组(SBE)。诊断性聚合酶链式反应显示，三组伯克霍尔德氏菌中只有一组与相似，而同一昆虫内多组伯克霍尔德氏菌感染的比例仅为10%。对16S rRNA基因的深度测序证实，伯克霍尔德氏菌专门在墓穴中定植，并由三个伯克霍尔德氏菌群中的一个主导。共生体与寄主种群之间缺乏系统发育的一致性强烈地提示了寄主-共生体的混杂，这可能是由于某些宿主对共生体的环境获取造成的。同时，通过诊断聚合酶链式反应和蛋表面灭菌对蛋和孵化的幼虫进行检测，发现近30%的孵化出的幼虫通过共生菌污染的蛋表面垂直获得共生的伯克霍尔德氏菌。在东方扁虱身上发现的共生体传播的混合策略可能是昆虫从环境获取到严格垂直传播进化的中间阶段。
The vertical transmission of symbiotic microorganisms is omnipresent in insects, while the evolutionary process remains totally unclear. The oriental chinch bug, Cavelerius saccharivorus (Heteroptera: Blissidae), is a serious sugarcane pest, in which symbiotic bacteria densely populate the lumen of the numerous tubule-like midgut crypts that the chinch bug develops. Cloning and sequence analyses of the 16S rRNA genes revealed that the crypts were dominated by a specific group of bacteria belonging to the genus Burkholderia of the Betaproteobacteria. The Burkholderia sequences were distributed into three distinct clades: the Burkholderia cepacia complex (BCC), the plant-associated beneficial and environmental (PBE) group, and the stinkbug-associated beneficial and environmental group (SBE). Diagnostic PCR revealed that only one of the three groups of Burkholderia was present in similar to 89% of the chinch bug field populations tested, while infections with multiple Burkholderia groups within one insect were observed in only similar to 10%. Deep sequencing of the 16S rRNA gene confirmed that the Burkholderia bacteria specifically colonized the crypts and were dominated by one of three Burkholderia groups. The lack of phylogenetic congruence between the symbiont and the host population strongly suggested host-symbiont promiscuity, which is probably caused by environmental acquisition of the symbionts by some hosts. Meanwhile, inspections of eggs and hatchlings by diagnostic PCR and egg surface sterilization demonstrated that almost 30% of the hatchlings vertically acquire symbiotic Burkholderia via symbiont-contaminated egg surfaces. The mixed strategy of symbiont transmission found in the oriental chinch bug might be an intermediate stage in evolution from environmental acquisition to strict vertical transmission in insects.