Bioresources and Management Laboratory, Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, Fukuoka 819-0395, Japan;
Institute of Biological Control, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan.
Proc Natl Acad Sci U S A. 2017 Jun 6;114(23):6110-6115. doi: 10.1073/pnas.1618094114. Epub 2017 May 22.
Maternally inherited bacterial endosymbionts in arthropods manipulate host reproduction to increase the fitness of infected females. Cytoplasmic incompatibility (CI) is one such manipulation, in which uninfected females produce few or no offspring when they mate with infected males. To date, two bacterial endosymbionts, and , have been reported as CI inducers. Only induces complete CI, which causes 100% offspring mortality in incompatible crosses. Here we report a third CI inducer that belongs to a unique clade of Alphaproteobacteria detected within the coconut beetle, This beetle comprises two cryptic species, the Asian clade and the Pacific clade, which show incompatibility in hybrid crosses. Different bacterial endosymbionts, a unique clade of Alphaproteobacteria in the Pacific clade and in the Asian clade, induced bidirectional CI between hosts. The former induced complete CI (100% mortality), whereas the latter induced partial CI (70% mortality). Illumina MiSeq sequencing and denaturing gradient gel electrophoresis patterns showed that the predominant bacterium detected in the Pacific clade of was this unique clade of Alphaproteobacteria alone, indicating that this endosymbiont was responsible for the complete CI. Sex distortion did not occur in any of the tested crosses. The 1,160 bp of 16S rRNA gene sequence obtained for this endosymbiont had only 89.3% identity with that of , indicating that it can be recognized as a distinct species. We discuss the potential use of this bacterium as a biological control agent.
节肢动物中母系遗传的细菌内共生体操纵宿主繁殖，以增加感染雌性的适合度。细胞质不亲和（CI）就是这样一种操纵方式，其中未感染的雌性与感染的雄性交配时很少或没有后代。迄今为止，已报道有两种细菌内共生体和 是 CI 的诱导剂。只有 能诱导完全 CI，在不相容杂交中会导致 100%的后代死亡。在这里，我们报告了第三种 CI 诱导剂，它属于在椰子甲虫中发现的α变形菌的一个独特分支。这种甲虫由两个隐生种组成，亚洲分支和太平洋分支，它们在杂交中表现出不亲和性。不同的细菌内共生体，即太平洋分支中的一个独特的α变形菌分支和亚洲分支中的 ，在宿主之间诱导了双向 CI。前者诱导完全 CI（100%死亡率），而后者诱导部分 CI（70%死亡率）。Illumina MiSeq 测序和变性梯度凝胶电泳图谱显示，在太平洋分支的 中检测到的主要细菌是这个独特的α变形菌分支，表明这种内共生体是完全 CI 的原因。在任何测试的杂交中都没有发生性别扭曲。从这个内共生体获得的 16S rRNA 基因序列的 1,160 bp 与 的只有 89.3%的同一性，表明它可以被识别为一个独特的物种。我们讨论了将这种细菌用作生物防治剂的潜力。
