Department of Biology, University of York, York, UK.
Microbiology Department, Cornell University, Ithaca, NY, USA.
ISME J. 2021 Sep;15(9):2537-2546. doi: 10.1038/s41396-021-00943-9. Epub 2021 Mar 12.
Microbial symbionts often alter the phenotype of their host. Benefits and costs to hosts depend on many factors, including host genotype, symbiont species and genotype, and environmental conditions. Here, we present a study demonstrating genotype-by-genotype (G×G) interactions between multiple species of endosymbionts harboured by an insect, and the first to quantify the relative importance of G×G interactions compared with species interactions in such systems. In the most extensive study to date, we microinjected all possible combinations of five Hamiltonella defensa and five Fukatsuia symbiotica (X-type; PAXS) isolates into the pea aphid, Acyrthosiphon pisum. We applied several ecological challenges: a parasitoid wasp, a fungal pathogen, heat shock, and performance on different host plants. Surprisingly, genetic identity and genotype × genotype interactions explained far more of the phenotypic variation (on average 22% and 31% respectively) than species identity or species interactions (on average 12% and 0.4%, respectively). We determined the costs and benefits associated with co-infection, and how these compared to corresponding single infections. All phenotypes were highly reliant on individual isolates or interactions between isolates of the co-infecting partners. Our findings highlight the importance of exploring the eco-evolutionary consequences of these highly specific interactions in communities of co-inherited species.
微生物共生体通常会改变宿主的表型。宿主的收益和成本取决于许多因素，包括宿主基因型、共生体的种类和基因型以及环境条件。在这里，我们展示了一项研究，该研究表明昆虫体内多种内共生体之间存在基因型与基因型（G×G）相互作用，并且首次对这种系统中 G×G 相互作用与物种相互作用的相对重要性进行了量化。在迄今为止最广泛的研究中，我们将五种 Hamiltonella defensa 和五种 Fukatsuia symbiotica（X 型；PAXS）分离株的所有可能组合微注射到豌豆蚜 Acyrthosiphon pisum 中。我们应用了几种生态挑战：一种寄生蜂、一种真菌病原体、热休克以及在不同宿主植物上的表现。令人惊讶的是，遗传身份和基因型与基因型相互作用解释了更多的表型变异（平均分别为 22%和 31%），而不是物种身份或物种相互作用（平均分别为 12%和 0.4%）。我们确定了共感染相关的成本和收益，以及这些与相应的单一感染相比如何。所有表型都高度依赖于共同感染伙伴的单个分离株或分离株之间的相互作用。我们的研究结果强调了在共同遗传物种群落中探索这些高度特异性相互作用的生态进化后果的重要性。
