miRNA调控麦长管蚜翅型分化的分子机理研究

The English grain aphid, Sitobion avenae (F.), is a devastating global pest for wheat crops. S. avenae adults exhibit two different morphological variants, winged and wingless, that exist among genetically-identical individuals produced by parthenogenic females. This wing dimorphism is observed in response to the environmental changes, and results in isogenic offspring in the subsequent generation showing difference in their wing development. MicroRNAs (miRNAs) are short single-stranded non-coding RNAs that regulate gene expression, particularly during development. In the proceeding phase of this research, we surveyed and compared miRNA expression profiles between early developmental stage of winged and wingless S. avenae. Building on the preliminary data, I hypothesize that the differentially expressed miRNAs modulate wing dimorphism in S. avenae. To test this hypothesis, I propose to carry out the following objectives: 1) concurrent miRNA and mRNA expression profiling to predict the potential miRNA target genes for wing dimorphism, 2) validation of these miRNA target genes using luciferase assay, and 3) ultimately, functional characterization of the candidate miRNAs and their target genes through in vivo RNAi. This research will shed light on the molecular mechanism of aphid wing dimorphism at both miRNA and mRNA levels. More importantly, it will provide novel molecular targets for the genetic management of phloem-feeding insect pest, S. avenae.

麦蚜是一类世界性的农业害虫，有翅蚜的迁飞扩散是其暴发为害的关键。大量研究表明miRNA在昆虫翅的生长发育过程中发挥着重要的调控作用，但有关miRNA调控蚜虫翅型分化的机制鲜有报道，且对这些基因功能的研究非常欠缺。本研究拟在前期鉴定的多个与麦长管蚜翅发育相关miRNAs的基础上，深入解析miRNA调控麦长管蚜翅型分化的表观遗传学机制：1）通过对转录组和小RNA测序结果的共表达分析及多软件分析，预测可能调控麦长管蚜翅型分化的miRNA及其靶基因；2）采用双荧光素酶报告系统等方法验证miRNA对其靶基因的调控关系；3）利用RNA干扰等技术，研究所鉴定的miRNA及其靶基因的功能。通过上述研究，明确miRNA对麦长管蚜翅型分化的调控机制。研究结果对于深入理解昆虫翅型分化的表观遗传学机制以及发展新的麦蚜治理策略都具有重要的理论和实践价值。

蚜虫是地球上最具破坏性的害虫之一，其中大约有250种可以在农林业和园艺业上造成危害。蚜虫具有典型的扩散多型性，通过生殖转换和翅型分化的调节，成功的躲避不良环境从而维持种群的繁衍，为蚜虫田间防控带来很大困难。在国家自然基金的资助下，本研究以麦长管蚜为研究对象，利用miRNA-mRNA联合分析研究麦蚜翅型分化的机理及在蚜虫防控中的应用技术。首先构建了麦长管蚜两种翅型共12个发育时期的miRNA文库和转录组文库，然后通过筛选鉴定获得一批在麦蚜翅发育通路中的关键miRNA和mRNA，最终对互靶关系的miRNA-mRNA的表达和功能进行验证。首次发现调控麦长管蚜翅型分化的6个miRNA，其中4种miRNA干扰剂处理会导致麦长管蚜不同程度的翅发育畸形，例如形成小翅、翅卷曲折叠和发育异常等；利用8种miRNA的干扰剂和4种基因的干扰剂处理蚜虫，对蚜虫具有很高的致死作用，致死率最高可达90%；同时miRNA-mRNA的干扰剂还会引起有翅率的降低，减少群体中有翅蚜的数量。本研究结果可用于开发基于miRNA-mRNA干扰剂的绿色防控技术，以及对于研究miRNA-mRNA介导的RNAi新型抗虫作物提供了候选资源，具有良好的商业化应用前景。