通过简化基因组深度测序解析灰飞虱迁飞特性及种群遗传结构

The small brown planthoppers(Laodelphax striatellus Fallén) and virus disease they transmitted are all serious threat to crop production. Migration of L. striatellus has brought badly serious influence to China, Japan and North Korea.Scholars at home and abroad have made studious researches in migration of SBPH and have proved that L. striatellus could play a long-distance migration, however, to date, there is no strong molecular evidence to support the conclusion, and some scholars have different opinions on the enfluence of migration to genetic structure.The data gained by normal molecular biotechnology is not enough to analyze difference between the L. striatellus populations, which prevents a further study to polymorphism of the small brown planthoppers. By SLAF-seq technique, we have got some sequence data of 13 SBPH populations from some regions where seriously suffered rice stripe disease. Previously, we have analyzed the sequece data and found 2572 SNPs among the populations. In this study, we want to do deep research on the basis of previous job. (1)we select the brown planthoppers to be a exotic population to establish the Phylogenetic tree according the sequence data, to study the geographic affinity among different regions and detect the molecular evidence of SBPH migration.(2) By analyzing the difference between sequence of SBPH populations to study the enfluence of SBPHs genetic structure caused by migration. (3) To develop some SNP or Indel markers used for polymorphism analysis of SBPHs.The results of this study is important for revealing the migration rules of SBPHs, monitoring the dynamics of SBPH populations and controlling the virus disease fundamentally.

灰飞虱及其传播的病毒病严重威胁着作物的生产，其迁飞为害已对中国、日本及朝鲜等国造成严重影响。国内外学者曾利用捕获等技术证明了灰飞虱可进行长距离大规模迁飞的特性，但目前尚无有力的分子证据支持该结论，对于迁飞对灰飞虱种群遗传结构的影响也众说不一。利用常规分子生物学手段获取的灰飞虱序列数据量小，限制了对灰飞虱多态性的研究。本申请前期利用简化基因组深度测序技术获得了13个条纹叶枯病重发区灰飞虱群体的简化基因组序列，并检测到2572个SNP，本研究拟在前期基础上开展以下研究（1）以褐飞虱为外群，获取不同地理区域灰飞虱的简化基因组序列，构建系统发育树，研究群体间的亲缘关系，寻找迁飞的分子证据。（2）基于灰飞虱群体间的序列差异研究迁飞对灰飞虱种群遗传结构的影响。（3）开发可用于灰飞虱多态性鉴定的SNP和Indel标记。本研究结果对于揭示灰飞虱的迁飞规律、监测种群动态及从根本上防控该虫的危害具重要意义。

灰飞虱是我国重要的农业害虫，已给我国农业生产造成较为严重的经济损失。分子标记是研究昆虫迁飞与扩散行为的重要手段，阐明昆虫种群分化、遗传结构及基因流，找到“DNA指纹”证据，进而揭示其起源、扩散路线及趋势。本研究利用多种分子标记技术，即线粒体基因、SSR及简化基因组深度测序技术(SLAF-seq和ddRAD)对我国不同地理种群灰飞虱种群遗传变异、遗传结构以及迁飞分子特征等进行系统研究，从分子水平上探讨了我国灰飞虱不同地理种群遗传进化关系及各发生危害区虫源关系，明确了我国灰飞虱不同地理种群间的遗传分化及基因流，阐明了该种害虫在我国的种群进化历史。总体上，基于上述四种分子标记，我国灰飞虱不同地理种群遗传多样性较低，不同地理种群间存在一定的遗传分化(灰飞虱东北种群以及中国西部种群与其他种群遗传分化较大)；简化基因组深度测序技术研究结果表明，灰飞虱在我国不同的气候区域内存在明显不对称基因流，推测其在我国东部季风区可能存在一定迁飞路径与迁飞规律；我国不同地理种群灰飞虱遗传关系复杂，没有明显的谱系遗传格局，这可能反映了广域内频繁的基因流和灰飞虱迁飞特性有关。分子变异等级分析表明，不同地理与气候条件并不是影响灰飞虱种群遗传结构与物种分布格局的主要因素。Mantel Test分析表明，地理距离和遗传距离存在一定相关性。中性检验和歧点分布分析发现，我国灰飞虱可能存在种群的近期扩张，并未经历过明显的瓶颈效应。. 鉴于此，本项目采用上述多种分子标记对我国不同地理种群灰飞虱虫源进行虫源追溯，探明其在我国不同气候生态区间的转移规律和不同区域间的虫源关系和虫源性质，为灰飞虱异地治理和有效防控提供理论支撑。