Variation and diversification of the microbiome of Schlechtendalia chinensis on two alternate host plants

Schlechtendalia chinensis, a gall-inducing aphid, has two host plants in its life cycle. Its wintering host is a moss (typically Plagiomnium maximoviczii) and its main host is Rhus chinensis (Sumac), on which it forms galls during the summer. This study investigated bacteria associated with S. chinensis living on the two different host plants by sequencing 16S rRNAs. A total of 183 Operational Taxonomic Units (OTUs) from 50 genera were identified from aphids living on moss, whereas 182 OTUs from 49 genera were found from aphids living in Sumac galls. The most abundant bacterial genus among identified OTUs from aphids feeding on both hosts was Buchnera. Despite similar numbers of OTUs, the composition of bacterial taxa showed significant differences between aphids living on moss and those living on R. chinensis. Specifically, there were 12 OTUs from 5 genera (family) unique to aphids living on moss, and 11 OTUs from 4 genera (family) unique to aphids feeding in galls on R. chinensis. Principal Coordinate Analysis (PCoA) also revealed that bacteria from moss-residing aphids clustered differently from aphids collected from galls. Our results provide a foundation for future analyses on the roles of symbiotic bacteria in plant-aphid interactions in general, and how gall-specific symbionts differ in this respect.角倍蚜（Schlechtendalia chinensis）是一种致瘿蚜虫，其完整生活史需依赖两种寄主植物。其越冬寄主为苔藓类物种，典型代表为大叶藓（Plagiomnium maximoviczii）；主要寄主为盐肤木（Rhus chinensis，俗称Sumac漆树），该蚜虫于夏季在盐肤木上形成虫瘿。本研究通过16S核糖体RNA（16S rRNAs）测序技术，对栖息于两种不同寄主上的角倍蚜所携带的共生细菌群落进行了分析。从苔藓寄主上的蚜虫样本中，共鉴定出隶属于50个属的183个操作分类单元（Operational Taxonomic Units，OTU）；而从盐肤木虫瘿内的蚜虫样本中，则鉴定出隶属于49个属的182个OTU。在两种寄主来源的蚜虫所携带的细菌类群中，布赫纳氏菌属（Buchnera）均为丰度最高的细菌属。尽管两组样本的OTU数量相近，但栖息于苔藓与盐肤木上的蚜虫其细菌群落组成存在显著差异。具体而言，苔藓寄主蚜虫专属的细菌类群包含5个属（科）级分类单元下的12个OTU，而盐肤木虫瘿内蚜虫专属的细菌类群则包含4个属（科）级分类单元下的11个OTU。主坐标分析（Principal Coordinate Analysis，PCoA）结果同样显示，苔藓栖息蚜虫的细菌群落与盐肤木虫瘿来源蚜虫的细菌群落聚类模式存在显著分化。本研究结果为后续解析共生细菌在植物-蚜虫互作中的普遍作用，以及虫瘿特异性共生菌在该过程中的功能差异提供了重要的研究基础。