基于烟粉虱生殖不亲和系的种群调控及其内在机制

The control of human disease vector insects based on Wolbachia-induced cytoplasmic incompatibility (CI) has reached the trial stage, but no advances have been made in the control of important agricultural pest insects by using this strategy. In recent years, we have established several different reproductively incompatible lines of Bemisia tabaci through artificial transinfection, which provides the prerequisite for CI-based control of B. tabaci. However, the maternal transmission rate and Wolbachia titre were shown to fluctuate during trans-generational passage, and how this fluctuation would influence the population control efficacy of the incompatible lines is still unclear. This proposal is planned to conduct the following studies by using different incompatible lines of B. tabaci: (1) Continuous measurement of the titres, maternal transmission rates and CI intensities of the incompatible lines, and conducting association analysis; (2) releasing incompatible males and conducting population suppression experiments and simulation; (3) releasing incompatible females and conducting population replacement and suppression experiments and simulation, and (4) functional analysis of the genes involved in molecular regulation of Wolbachia titre. These studies are aimed to elucidate the inherent mechanisms by which the change in Wolbachia titre influences the population regulation capability of the incompatible lines through the change in maternal transmission rate and CI intensity and decipher the molecular regulatory mechanisms of Wolbachia titre. The systematic data resulted from this project will not only provide scientific basis for CI-based reproductive regulation of B. tabaci populations, but can also provide references for ecological regulation of other important agricultural pest insects, and help us penetrate the symbiotic interactions between Wolbachia and the host.

运用Wolbachia诱导的胞质不亲和（CI）防控传病媒介昆虫已进入应用测试阶段，但其在重要农业害虫防控上尚未见进展。我们近年通过人工转染建立了多个烟粉虱生殖不亲和系，为应用该策略防控烟粉虱提供了前提条件，但外源菌株在传代过程中出现了母系传递率和滴度的波动，而这种波动对于不亲和系的种群调控效能有何影响目前不清楚。本项目拟采用多个烟粉虱不亲和系开展如下研究：（1）菌株滴度、母系传递率和CI强度连续测定及其关联性分析；（2）不亲和雄虫释放及种群抑制实验和模拟；（3）不亲和雌虫释放及种群取代/抑制实验和模拟；（4）菌株滴度调控的基因功能分析。上述研究旨在揭示菌株滴度的变化如何通过母系传递率和CI强度影响不亲和系的种群调控效能及其内在机制，所获得的系统性数据将为基于CI调控烟粉虱种群提供可靠依据，也可为其它重要农业害虫的生态调控提供参考，还有助于深入理解Wolbachia与宿主间的共生互作机制。

运用Wolbachia诱导的胞质不亲合性（CI）防控重要农业害虫具有可行性。本课题组近年来通过人工转染建立了多个烟粉虱生殖不亲合系，这一方面为基于CI的烟粉虱防控策略提供了良好的研究系统，另一方面也为研究Wolbachia-宿主互作机制提供了实验模型。我们在运用该研究系统优化外源菌株调控靶标种群的效能的过程中，发现外源菌株在新宿主中的滴度和传递率都不稳定。因此，如果要提高外源菌株的调控效能，就必须首先弄清其滴度和传递率的调节机制。本项目针对上述科学问题进行了一系列研究，取得如下主要进展：（I）外源wMel菌株侵染烟粉虱可抑制Toll 和Imd 信号通路，从而阻止抗菌肽的生物合成，但不能限制胞吞和包囊化作用，这为研究Wolbachia与宿主的互作关系提供了基础数据；（II）采用多种算法，筛选出一套稳定的针对烟粉虱gDNA和cDNA的内参基因，这对于检测Wolbachia的滴度及宿主基因的应答反应必不可少；（III）外源wCcep菌株可成功跨目转染到黑腹果蝇，但只能在新宿主中传递4代。wCcep的侵染可引起宿主强烈的防御反应，并招致本地的wMel菌株的竞争排斥，最终导致其在新宿主定殖失败；（IV）wMel菌株的跨代传递受其滴度调节，而免疫基因（Drsl5和Spn38F）参与了Wolbachia滴度的调控过程；（V）建立了一项针对Wolbachia转染的精准化差异转录组测序技术，并运用该技术鉴定了7个参与外源菌株滴度调控的热激蛋白（HSP70）基因，这为Wolbachia-宿主互作研究中候选基因的功能验证提供了一个优化模型；（VI）测定了wCcep菌株的全基因组序列，并运用比较基因组学，揭示了一种全新的Wolbachia诱导CI的分子机制。这些研究成果为揭示Wolbachia菌株滴度的调控机制以及滴度的变化如何影响母系传递率和CI强度，并最终通过人为控制这些变化以达到利用Wolbachia对重要农业害虫种群进行生态调控的目的提供了科学依据。在本项目资助下，截止目前，标注本项目已正式发表的研究论文9篇（SCI），另有1篇待发表。本项目重点资助博士生3名和硕士生4名。