Cassone Bryan J, Wenger Jacob A, Michel Andrew P
1. Department of Biology, Brandon University, Brandon, MB R7A 6A9, Canada.
2. Department of Entomology, The Ohio State University, OARDC, Wooster, OH 44691, USA.
J Genomics. 2015 Oct 5;3:85-94. doi: 10.7150/jgen.12975. eCollection 2015.
Endosymbiosis with microorganisms is common in insects, with more than 10% of species requiring the metabolic capabilities of intracellular bacteria for their nutrient acquisition. Aphids harbor an obligate mutualism with the vertically transferred endosymbiont, Buchnera aphidicola, which produces key nutrients lacking in the aphid's phloem-based diet that are necessary for normal development and reproduction. It is thought that, in some groups of insects, bacterial symbionts may play key roles in biotype evolution against host-plant resistance. The genome of Buchnera has been sequenced in several aphid strains but little genomic data is currently available for the soybean aphid (Aphis glycines), one of the most important pests of soybean in North America. In this study, DNA sequencing was used to assemble and annotate the genome sequence of the Buchnera A. glycines strain and to reconstruct phylogenetic relationships among different strains. In addition, we identified several fixed Buchnera SNPs between Aphis glycines biotypes that were avirulent or virulent to a soybean aphid resistance gene (Rag1). The results of this study describe the genetic and evolutionary relationships of the Buchnera A. glycines strain, and begin to define the roles of an aphid symbiont in host-plant resistance.
与微生物的内共生现象在昆虫中很常见，超过10%的昆虫物种需要细胞内细菌的代谢能力来获取营养。蚜虫与垂直传播的内共生菌——蚜虫内共生菌（Buchnera aphidicola）存在专性共生关系，这种细菌能产生蚜虫以韧皮部为食的饮食中缺乏的关键营养物质，这些营养物质对蚜虫的正常发育和繁殖至关重要。据认为，在某些昆虫群体中，细菌共生体可能在对抗宿主植物抗性的生物型进化中发挥关键作用。蚜虫内共生菌的基因组已在多个蚜虫菌株中进行了测序，但目前关于大豆蚜虫（Aphis glycines）的基因组数据很少，大豆蚜虫是北美大豆最重要的害虫之一。在本研究中，利用DNA测序来组装和注释大豆蚜虫内共生菌菌株的基因组序列，并重建不同菌株之间的系统发育关系。此外，我们在对大豆蚜虫抗性基因（Rag1）无毒或有毒的大豆蚜生物型之间鉴定了几个固定的蚜虫内共生菌单核苷酸多态性。本研究结果描述了大豆蚜虫内共生菌菌株的遗传和进化关系，并开始确定蚜虫共生体在宿主植物抗性中的作用。
