水稻褐飞虱境外虫源不同种群遗传分化和迁飞分子标记研究

The brown planthopper (BPH, Nilaparvata lugens) is a long-distance migration insect and the most destructive rice pest, which seriously threaten the food safety of China. The northern geographic limit of winter breeding for the BPH is approximately 23-25°N, and this species does not survive winter in temperate regions which include most rice cultivation areas in China. The original BPH sources which cause outbreaks and result huge loss every year in main rice cultivation areas of China are known to come from Southeastern Asian countries. BPH’s damage may be characterized as “international, migrated, outbreak and devastating”. As the insect sources are from overseas, to manage BPH in China, we should pay our attention more on Southeastern and South Asia. To better understand the outbreak mechanism，BPH sources and their detail migration routes, we need first to determine the genetic diversities of different populations in Southeastern and South Asia countries with the potential BPH sources. However, we know little about these up to date. In this proposal, using our completed BPH and its two endosymbionts’ genomes as reference sequences, we plan to re-sequencing 30 individuals of each of nine geographic populations from Southeastern and South Asian countries, and analyze their genetic structures and diversities， including SNP frequencies related to insecticides resistance and virulences, and then select molecular marker groups which can be used to distinguish different geographic populations. Using these selected molecular markers, we will further detect BPH samples from different main rice cultivation areas in China, and figure out their oversea BPH sources and their compositions, and track the migratory routes. Our results will provide a solid basis for BPH control and further studies of the insect sources and tracking the detailed migration routes on a larger scale.

褐飞虱是长距离迁飞的水稻毁灭性害虫，严重威胁我国粮食安全。其越冬北限约在北纬23-25°，在我国大多数温带水稻产区不能越冬，我国虫源每年主要来自东南亚国家。褐飞虱危害具有“国际性、迁飞性、爆发性、毁灭性”特点。因虫源在境外,解决中国褐飞虱问题，必须把眼光放到国外。确定东南亚和南亚的褐飞虱潜在虫源地的种群遗传结构,是探索我国褐飞虱虫源、迁飞路线和研究其爆发成灾机理的前提，但境外虫源及其遗传结构还不很清楚。本研究拟在我们已完成的褐飞虱和其细胞内共生菌全基因组基础上，通过对潜在虫源地的9个东南亚地理种群进行个体基因组重测序，绘制各地理种群群体全基因组结构变异图谱，确定不同种群群体结构、不同抗药性和致害性频率，并筛选可用于区分不同地理种群的分子标记组合，对我国主要产稻区初次褐飞虱虫源进行检测，初步分析我国主要初次虫源的境外来源和预测迁飞途径，为我国褐飞虱防治、爆发虫源确定和分析精细迁飞路线提供基础

动物的季节性迁飞显著地影响地球的生态系统，许多毁灭性的农作物害虫属于非直接和被动的迁飞类型。对非1代迁飞到位的被动小型害虫迁飞路径目前还存在诸多争议，其遗传机理还很不清楚。褐飞虱(Nilaparvata lugens)是水稻上一种重要的迁飞害虫，其在我国大部分稻区不能越冬,每年从东南亚越冬地迁飞入我国为害。但目前对褐飞虱种群遗传分化和迁飞扩散仍所知有限。本研究中我们首先组装了褐飞虱雄虫染色体水平基因组，第一个从不完全变态昆虫中鉴定出了Y染色体，为种群遗传分化和进化提供了重要参考基因组。同时我们通过全球合作，采集了来自全球水稻区92个褐飞虱种群，对其中358头代表性个体进行了全基因组测序，从遗传角度揭示了全球不同种群的遗传关系和它们的扩散景观。分析表明全球褐飞虱分为南亚、东南亚、东亚三大迁飞群和澳大利亚、孟加拉及福建本地化种群。首次发现三大迁飞群中只有东亚迁飞群在远东地区和中南半岛之间可以形成闭环迁飞，而南亚和东南亚迁飞群只有单向迁飞向中南半岛，这也表明了迁飞对重塑种群结构具强大功能作用。选择压力分析表明8号染色体存在与长距离迁飞导致爆发成灾的相关高选择区域，同时我们发现主要农药抗性突变位点的全球分布与农药使用相关，为抗性进化和检测提供了依据。种群独有SNP提供了区分种群marker基础。同时我们还更深入地开展了与褐飞虱种群形成和种群内个体变化相关的翅型分化、体色调控、表皮蛋白和碳氢化合物组成与变化、性别决定、繁殖、在高温和低温环境下基因表达差异、适应敏感和抗性水稻品种的唾液蛋白与变化等进行了拓展和深入分析，这些研究结果加深了我们对种群形成机理的理解。本研究结果不仅在季节性迁飞推动物种分化和进化上有重要理论价值，也为褐飞虱预警和防治提供了重要的基因组资源。以上结果部分已经整理成35篇论文先后在PNAS、eLife、Science Advances、 Ann Rev Entomol、 Genetics、FASEB Journal、Molecular Ecology、Molecular Ecology Resources、IBMB等杂志上发表，其中第一标注论文26篇。总之本课题已经高质量和超额完成了预定研究内容和目标。