Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA.
mBio. 2024 Jun 12;15(6):e0325323. doi: 10.1128/mbio.03253-23. Epub 2024 May 7.
Insects frequently form heritable associations with beneficial bacteria that are vertically transmitted from parent to offspring. Long-term vertical transmission has repeatedly resulted in genome reduction and gene loss, rendering many such bacteria incapable of establishment in axenic culture. Among aphids, heritable endosymbionts often provide context-specific benefits to their hosts. Although these associations have large impacts on host phenotypes, experimental approaches are often limited by an inability to cultivate these microbes. Here, we report the axenic culture of Fukatsuia symbiotica strain WIR, a heritable bacterial endosymbiont of the pea aphid, . Whole-genome sequencing revealed similar genomic features and high sequence similarity to previously described strains, suggesting that the cultivation techniques used here may be applicable to . F. symbiotica strains from distantly related aphids. Microinjection of cultured . F. symbiotica into uninfected aphids revealed that it can reinfect developing embryos and that infections are maintained in subsequent generations via transovarial maternal transmission. Artificially infected aphids exhibit phenotypic and life history traits similar to those observed for native infections. Our results show that . F. symbiotica may be a useful tool for experimentally probing the molecular mechanisms underlying host-symbiont interactions in a heritable symbiosis.
Diverse eukaryotic organisms form stable, symbiotic relationships with bacteria that provide benefits to their hosts. While these associations are often biologically important, they can be difficult to probe experimentally because intimately host-associated bacteria are difficult to access within host tissues, and most cannot be cultured. This is especially true for the intracellular, maternally inherited bacteria associated with many insects, including aphids. Here, we demonstrate that a pea aphid-associated strain of the heritable endosymbiont, Fukatsuia symbiotica, can be grown outside of its host using standard microbiology techniques and can readily re-establish infection that is maintained across host generations. These artificial infections recapitulate the effects of native infections, making this host-symbiont pair a useful experimental system.
昆虫经常与有益细菌形成可遗传的联系，这些细菌从亲代垂直传递给后代。长期的垂直传递导致许多细菌的基因组缩小和基因丢失，使其无法在无菌培养中建立。在蚜虫中，可遗传的内共生体经常为其宿主提供特定环境的益处。尽管这些关联对宿主表型有很大影响，但实验方法往往受到无法培养这些微生物的限制。在这里，我们报告了豌豆蚜的可遗传细菌内共生体 Fukatsuia symbiotica 菌株 WIR 的无菌培养。全基因组测序显示出相似的基因组特征和与先前描述的菌株的高度序列相似性，这表明这里使用的培养技术可能适用于来自远缘蚜虫的 Fukatsuia symbiotica 菌株。将培养的 Fukatsuia symbiotica 微注射到未感染的蚜虫中，结果表明它可以重新感染发育中的胚胎，并且通过经卵母体传递，感染在随后的世代中得以维持。人工感染的蚜虫表现出与天然感染相似的表型和生活史特征。我们的研究结果表明，Fukatsuia symbiotica 可能是一种有用的工具，可以用于实验探究在可遗传共生关系中宿主-共生体相互作用的分子机制。
不同的真核生物与为其宿主提供益处的细菌形成稳定的共生关系。尽管这些关联通常具有生物学意义，但由于与宿主密切相关的细菌难以在宿主组织内获得，并且大多数细菌不能在培养中生长，因此它们很难进行实验研究。这在包括蚜虫在内的许多昆虫中与体内共生的、可遗传的细菌尤其如此。在这里，我们证明了豌豆蚜相关的可遗传内共生体 Fukatsuia symbiotica 菌株可以使用标准微生物学技术在宿主外生长，并可以重新建立在宿主代际中维持的感染。这些人工感染再现了天然感染的效果，使这种宿主-共生体对成为有用的实验系统。
