Uncovering symbiont-driven genetic diversity across North American pea aphids
Uncovering symbiont-driven genetic diversity across North American pea aphids
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DOI：
10.1111/mec.12211
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发表时间：
2013-04-01
影响因子：
4.9
通讯作者：
Oliver, Kerry M.
中科院分区：
文献类型：
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作者：
Russell, Jacob A.;Weldon, Stephanie;Oliver, Kerry M.
可遗传的遗传变异是进化所必需的，虽然通常编码在细胞核和细胞器基因组中，但几组无脊椎动物含有可遗传的微生物，作为遗传变异的额外来源。海陵是一种共生体丰富的半翅目昆虫，具有多种可遗传的共生体，在寄主植物利用、耐热性和保护天敌等方面具有重要作用。由于豌豆蚜虫的数量和类型不同的窝藏共生体，这些细菌提供了遗传和功能上的重要变化领域内的人口。在这项研究中，我们量化了北美豌豆蚜虫内共生体所贡献的细胞质遗传遗传变异。通过使用变性梯度凝胶电泳（DGGE）和454扩增子焦磷酸测序的16S rRNA基因，我们探讨了豌豆蚜虫窝藏的细菌的多样性，从5个种群，跨越3个地点和3种寄主植物。我们还通过分析16S rRNA，管家和共生体相关的噬菌体基因的菌株变异的特点。我们的研究结果确定了8种兼性共生体，这往往是不同的位置和宿主植物之间的频率。我们在318个被调查的蚜虫中检测到28种细胞质基因型，仅考虑次级共生体物种感染单一宿主的各种组合。然而，检测到多种昆虫生雷吉氏菌、防御汉米尔顿氏菌和立克次氏体菌株，以及来自防御汉米尔顿氏菌的多种噬菌体基因型，表明了更大的多样性。结合，这些研究结果表明，遗传性细菌的贡献很大的遗传变异在A.豌豆。考虑到这些共生体的成本和收益，波动的选择力可能在维持这种多样性方面发挥作用。
Heritable genetic variation is required for evolution, and while typically encoded within nuclear and organellar genomes, several groups of invertebrates harbour heritable microbes serving as additional sources of genetic variation. Hailing from the symbiont-rich insect order Hemiptera, pea aphids (Acyrthosiphon pisum) possess several heritable symbionts with roles in host plant utilization, thermotolerance and protection against natural enemies. As pea aphids vary in the numbers and types of harboured symbionts, these bacteria provide heritable and functionally important variation within field populations. In this study, we quantified the cytoplasmically inherited genetic variation contributed by symbionts within North American pea aphids. Through the use of Denaturing Gradient Gel Electrophoresis (DGGE) and 454 amplicon pyrosequencing of 16S rRNA genes, we explored the diversity of bacteria harboured by pea aphids from five populations, spanning three locations and three host plants. We also characterized strain variation by analysing 16S rRNA, housekeeping and symbiont-associated bacteriophage genes. Our results identified eight species of facultative symbionts, which often varied in frequency between locations and host plants. We detected 28 cytoplasmic genotypes across 318 surveyed aphids, considering only the various combinations of secondary symbiont species infecting single hosts. Yet the detection of multiple Regiella insecticola, Hamiltonella defensa and Rickettsia strains, and diverse bacteriophage genotypes from H.defensa, suggest even greater diversity. Combined, these findings reveal that heritable bacteria contribute substantially to genetic variation in A.pisum. Given the costs and benefits of these symbionts, it is likely that fluctuating selective forces play a role in the maintenance of this diversity.