灰飞虱核心共生菌的鉴定

Identification of the core symbiotic bacteria of Laodelphax striatellus

摘要:

媒介昆虫的核心共生菌能被用作基因工程菌发挥抗病毒功能。灰飞虱是一种重要的农业害虫，其传播的水稻条纹病毒造成水稻的大面积减产甚至绝收。【目的】本研究对不同稻区及温室饲养的灰飞虱进行菌群组成分析并初步鉴定灰飞虱的核心共生菌。【方法】通过16S rDNA介导的二代测序技术，分析了2018-2020年间采集自云南昆明、河南开封、河南范县稻区以及温室的灰飞虱的菌群组成。【结果】所有37个灰飞虱测序样本均携带细胞内和细胞外共生菌，细胞内生菌沃尔巴克氏体属（Wolbachia）为灰飞虱最稳定的核心共生菌，在所有样本中存在，平均相对丰度51.96%，其代表性序列OTU45占据该属85条OTU序列总数的96.55%。除Wolbachia之外，其他常见核心菌均为胞外菌，其中4种平均相对丰度最高的常见核心菌分别为不动杆菌属、泛菌属、肠杆菌属和假单胞菌属，在10种常见核心菌中平均占比0.25%-2.97%。不同稻区的灰飞虱各有优势菌，昆明为立克次体属，范县为杀雄菌属和Cardinium，开封为醋杆菌属、泛菌属和Sulcia。这些田间的优势菌包括多种细胞内生菌。稻田灰飞虱在温室进行24 h蔗糖饲喂后，Wolbachia相对丰度显著升高，菌群结构与温室灰飞虱更加接近；继代培养后，除Wolbachia之外的细胞内生菌丢失或以低丰度存在于部分样本中。【结论】本研究初步阐明灰飞虱的菌群组成并鉴定了常见核心菌及3个中国稻区的优势共生菌，为通过核心菌进行抗病毒的研究提供了可选择的共生工程菌靶标。

Abstract:

The core symbiotic bacteria of insect vectors have the potential to be used as genetically engineered bacteria to control arboviruses. Laodelphax striatellus is an important agricultural pest and also the transmission vector of rice stripe virus, the causative agent of rice stripe disease that occurred with dramatic yield reduction or even no harvest.[Objective] In this study, the bacterial communities of L. striatellus were sequenced through 16S rDNA next-generation sequencing methods, and the core symbiotic bacteria were identified.[Methods] From 2018 to 2020, L. striatellus have been collected from the rice fields in Kunming of Yunnan Province, and in Kaifeng and Fanxian of Henan province, as well as in the greenhouse, in which microbiomes were sequenced and analyzed.[Results] All 37 L. striatellus sequencing samples carry both intracellular and extracellular bacteria. In the genus level, the intracellular bacteria Wolbachia exhibited the highest average relative abundance of 51.96%. Its representative OTU (OTU45) accounts for 96.55% of the total number of 85 OTUs and exists in all sequenced insect samples. Except for Wolbachia, all the other common core bacteria were extracellular, in which the four core genera with high abundances were Acinetobacter, Pantoea, Enterobacter and Pseudomonas, with average relative abundances of 0.25%-2.97% in all ten common core genera. There are dominant bacteria in insect samples from different rice fields. High-abundant Rickettsia were found in Kunming samples, both Arsonophonus and Cardinium were identified in Fanxian samples, and Acetobacter, Sulcia and Pantoea were found in Kaifeng samples. These rice-field dominant bacteria include a variety of intracellular bacteria. When the rice-field insects were fed with sucrose for 24 h in the greenhouse, the relative abundance of Wolbachia increased significantly and the microbial composition became closer to that of the greenhouse. Within the offsprings of these rice-field insects, the intracellular bacteria, except for Wolbachia, lost or existed in a few samples with low level.[Conclusion] This study preliminarily clarified the symbiotic bacterial composition of L. striatellus, identified common core bacteria and identified dominant symbiotic bacteria in the three Chinese rice areas, providing engineered bacteria for antiviral research through insect vector's core bacteria.