Elucidating the coevolutionary dynamics in an obligate insect symbiosis

许多昆虫，包括危害农作物和传播疾病的害虫，都依靠共生细菌生存。这种被称为微生物群的共生细菌群落生活在宿主的细胞和组织中，并直接从母亲传给后代。例如，这些细菌通常通过产生饮食中缺失的必需营养物质而使宿主受益。但共生体也会经历对宿主有害的基因变化。该项目探讨了共生体的有害进化是否以及如何影响其寄主昆虫。这里的重点是这样一个群体--蚜虫，它们攻击我们的大部分农作物，需要共生细菌才能生长和繁殖。这项研究将被用作向德克萨斯大学本科生教授基础生物学和遗传学的基础，其中包括一个大型新生研究项目的参与者。此外，这些结果将进一步了解一类重要的农业害虫，可能有助于开发新的作物保护方法。实验研究了豌豆蚜虫的遗传变异如何影响它们调节共生细菌的能力，以及共生细菌的遗传变异如何影响它们在蚜虫宿主内的繁殖。研究人员测量了共生菌调控的变化如何影响蚜虫的生长和繁殖。不同共生菌水平的蚜虫的实验遗传杂交将与现代DNA测序方法相结合，以识别影响共生菌数量的蚜虫基因组部分。此外，共生菌菌株将通过显微注射在蚜虫寄主之间转移，以确定不同的共生菌菌株如何影响寄主。

Many insects, including pest species that harm crops and transmit disease, depend on symbiotic bacteria for survival. This community of symbiotic bacteria, known as the microbiome, lives inside their host's cells and tissues and is passed directly from mother to offspring. These bacteria often benefit their hosts, for example, by producing required nutrients missing from the diet. But symbionts also can undergo genetic changes detrimental to hosts. This project addresses whether and how detrimental evolution of symbionts affects their host insects. The focus here is on one such group, aphids, which attack most of our agricultural crops and require symbiotic bacteria in order to grow and reproduce. The research will be used as a basis for teaching basic biology and genetics to University of Texas undergraduate students, including participants in a large freshman research program. Also, the results will further understanding of a significant group of agricultural pests, potentially contributing to the development of new methods of crop protection.The experiments address how genetic variation of pea aphids affects their ability to regulate symbiotic bacteria and how genetic variation of the symbiotic bacteria affects their own multiplication within aphid hosts. The researchers measure how variation in symbiont regulation affects aphid growth and reproduction. Experimental genetic crosses of aphids that vary in levels of symbiotic bacteria will be combined with modern DNA sequencing methods to identify the parts of the aphid genome that affect symbiont numbers. In addition, symbiont strains will be transferred between aphid hosts using microinjection, to determine how different symbiont strains affect hosts.