Variation in density, immune gene suppression, and coinfection outcomes among strains of the aphid endosymbiont Regiella insecticola
Variation in density, immune gene suppression, and coinfection outcomes among strains of the aphid endosymbiont Regiella insecticola
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DOI：
10.1093/evolut/qpad071
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发表时间：
2023-05-08
期刊：
影响因子：
3.3
通讯作者：
Parker, Benjamin J.
中科院分区：
文献类型：
--
作者：
Goldstein, Elliott B.;de Anda Acosta, Yazmin;Parker, Benjamin J.
许多昆虫含有影响宿主表型的可遗传微生物。共生菌株在宿主体内以不同的密度建立。这种变异在进化上是重要的，因为宿主内密度与共生双方的成本和收益有关。研究影响宿主内密度的因素对我们更广泛地理解宿主-微生物共同进化非常重要。在这里，我们集中在不同菌株的雷贾拉杀虫剂，一个兼性共生体的蚜虫。我们首先证明了雷吉氏菌菌株在豌豆蚜虫中以截然不同的密度建立。然后我们发现密度的变化与两种关键昆虫免疫系统基因（酚氧化酶和血细胞素）的表达水平相关，而免疫基因表达的抑制与较高的Regiella密度相关。然后我们进行了一个实验，我们建立了一个高密度和低密度的雷吉氏菌菌株的共同感染，我们表明高密度菌株比低密度菌株更能在共同感染中持续存在。总之，我们的研究结果指出了一个潜在的机制，该机制有助于该系统中共生密度的菌株水平变化，我们的数据表明，共生适应性可能通过在宿主体内建立更高的密度来增加。我们的工作强调了宿主内动态影响共生进化的重要性。
Many insects harbor heritable microbes that influence host phenotypes. Symbiont strains establish at different densities within hosts. This variation is important evolutionarily because within-host density has been linked to the costs and benefits of the symbiosis for both partners. Studying the factors shaping within-host density is important to our broader understanding of host-microbe coevolution. Here we focused on different strains of Regiella insecticola, a facultative symbiont of aphids. We first showed that strains of Regiella establish in pea aphids at drastically different densities. We then found that variation in density is correlated with the expression levels of two key insect immune system genes (phenoloxidase and hemocytin), with the suppression of immune gene expression correlating with higher Regiella density. We then performed an experiment where we established coinfections of a higher- and a lower-density Regiella strain, and we showed that the higher-density strain is better able to persist in coinfections than the lower-density strain. Together, our results point to a potential mechanism that contributes to strain-level variation in symbiont density in this system, and our data suggest that symbiont fitness may be increased by establishing at higher density within hosts. Our work highlights the importance of within-host dynamics shaping symbiont evolution.