云南Tospoviruses新种及其病害发生的遗传进化机制

Diseases caused by emerging tospoviruses are important limiting factors in many crop production systems worldwide. To date, ten species of tospoviruses have been found in Yunnan province and new tospovirus diseases are being discovered continuously. These diseases have caused and are continuing to cause significant losses in yield and quality of products from economically important crops such as vegetable, tobacco and ornamental crops. Due to the limitations of research methods, the emergence of viral diseases were attributed to the ecological changes，little is known about genetic evolution of viruses by allowing them to adapt to changes in their host and vectors. Based on our preliminary research, this project will use metagenomic approach to analysis the underlying genetic structure of 1 to 2 new species of tospoviruses infecting naturally intermediate hosts, cultivated crop hosts and vectors (insect hosts) in Yunnan. Main species of thrips and 2 to 3 tospovirus isolates between them there exsits evident genetics variations will be used as study subjects. Genetic variation of viruses and their adaptation to hosts and vectors will be analyzed through evaluating the pathogenicity of tospoviruses to the different hosts, the efficiencies of thrips in acquiring and transmitting tospoviruses in combination with sequence analysis of virus genes. Results of these studies will help to uncover the pattern of genetic variation and evolution of inter and intra-tospoviruses, and to explore the emergence mechanism of new tospoviruses and diseases. These results will provide valuable information in better understanding of the mechanism of tospoviruses origin and evolution, and in the development of ecologically sound methods in the monitor and control of diseases caused by tospoviruses.

新出现的番茄斑萎病毒属病毒引起世界范围内多种农作物病害。云南已发现10种该属新病毒病害为害蔬菜、花卉、烟草等经济作物，且新病毒病害仍不断出现。受研究方法的限制，新病毒及其病害的出现发生通常归因于生态因素改变，而对病毒为适应不同寄主、介体而发生的遗传进化研究较少。本项目在前期基础上，选择云南番茄斑萎病毒属新病毒1～2种作为研究对象，利用宏基因组学方法对自然侵染中间寄主、传毒介体蓟马(昆虫寄主)、栽培作物的番茄斑萎病毒属病毒进行基因组测序，研究病毒适应不同寄主、介体的种群遗传结构特征；选择遗传变异显著的病毒分离物2～3种，评价病毒对不同寄主作物的致病性、蓟马传毒效率，结合病毒基因序列分析，研究病毒遗传变异及其对寄主、介体的适应性；从而揭示病毒种间、种内的遗传进化规律，并探讨新病毒病害出现机制。本项目的开展有助于探索番茄斑萎病毒属起源和进化机制，为该类病毒新发病害的早期监测和生态控制提供科学依据

新出现的番茄斑萎病毒属病毒和病害是云南番茄、辣椒、烟草、花卉等园艺作物上的重要病害，为揭示新病毒和新病害出现的机制，本研究对采自云南的1230份样品进行了研究，发现11种病毒，其中4种新病毒即朱顶红褪绿环斑病毒(HCRV)、番茄坏死斑点病毒(TNSaV)、Kon-Tosp、辣椒黄化斑点病毒(CYSV)，7种新分离物即番茄环纹斑点病毒(TZSV)、辣椒褪绿病毒(CaCV)、花生黄斑病毒(GYSV)、凤仙花坏死斑点病毒(INSV)、西瓜银色斑点病毒(WSMoV)、辣椒褪绿斑点病毒(PCSV)、番茄斑萎病毒(TSWV)；发现云南番茄斑萎病毒属病毒的主要传毒介体为西花蓟马、棕榈蓟马、烟蓟马；发现病毒主要作物寄主有番茄、辣椒、烟草、莴苣、朱顶红等，发现鬼针草是最重要的杂草寄主。田间病害种类、传毒蓟马种群调查结果说明番茄斑萎病毒属病毒与其传毒蓟马高度适应是病害爆发的关键。建立了番茄斑萎病毒属病毒全基因组序列测定的技术体系，可一次性测定该属病全基因组序列，解决了常规RT-PCR耗时长、成本高的问题。利用该体系测定了25个分离物的全基因组序列，其中包括6个TSWV分离物、15个TZSV分离物。序列分析发现，点突变是云南TSWV、TZSV变异的主要方式；云南TSWV分离物 CG、LE、JNT发生重组，分离物YMT发生重配；云南TZSV有重组发生，但重组事件不频繁且不是云南TZSV遗传进化的关键机制，重配现象仍需要更多序列分析获得证据；全基因组分析发现连续机械接毒对TZSV进化影响较小，解析了入侵种TSWV及本地种TZSV在云南发生的遗传进化机制。生态多样性是云南番茄斑萎病毒属病毒丰富的环境基础，造就了云南番茄斑萎病毒属病毒新种多、新分离物与世界其它地方分离物差异大。项目研究结果丰富了我国番茄斑萎病毒种类，加深了对该属病毒起源、遗传进化的了解，为病害防控提供了重要线索。