Parker Benjamin J
Department of Microbiology, University of Tennessee, Knoxville, Tennessee, USA.
mSystems. 2021 Aug 31;6(4):101128msystems0072821. doi: 10.1128/mSystems.00728-21.
Within-host density is a critically important aspect of vertically transmitted symbioses that influences the fitness of both hosts and microbes. I review recent studies of symbiont density in insects, including my laboratory's work on pea aphids and maternally transmitted bacteria. These studies used systems approaches to uncover the molecular mechanisms of how both hosts and microbes influence symbiont density, and they shed light on whether optimal density is different from the perspective of host and microbial fitness. Mounting empirical evidence suggests that antagonistic coevolution shapes vertically transmitted symbioses even when microbes provide clear benefits to hosts. This is potentially because of differing selective pressures at the host and within-host levels. Considering these contrasting evolutionary pressures will be critically important in efforts to use vertically transmitted symbionts for biocontrol and as lessons from model systems are applied to the study of more complex microbiomes.
宿主体内共生菌密度是垂直传播共生关系的一个至关重要的方面，它会影响宿主和微生物双方的适应性。我回顾了近期关于昆虫共生菌密度的研究，包括我实验室对豌豆蚜和母系传播细菌的研究。这些研究采用系统方法来揭示宿主和微生物如何影响共生菌密度的分子机制，并阐明从宿主和微生物适应性的角度来看，最佳密度是否有所不同。越来越多的实证证据表明，即使微生物对宿主有明显益处，拮抗协同进化仍塑造着垂直传播的共生关系。这可能是由于宿主层面和宿主体内层面存在不同的选择压力。在利用垂直传播的共生菌进行生物防治以及将模型系统的经验应用于更复杂微生物群落研究的过程中，考虑这些相互矛盾的进化压力将至关重要。
