麦长管蚜翅型分化相关microRNAs的鉴定及功能研究

Abstract: Molecular mechanisms underlying the wing evolution and development have been a point of discussion for decades. Phloem-feeding aphids are one of the most devastating insect pests, wings has contributed to their range expansion as well as their status as a global insect pest. As a classic wing dimorphism insect, however, aphids offer a model to study the confluence of environmental and genetic variations on the morphological plasticity in wings. Although excellent progresses have been made toward molecular understanding of genetic contributions to wing formation, few have explored how environmental cues influence the polymorphism. The overall goal of this research is to link an epigenetic factor, microRNA (miRNA), with phenotypic plasticity in the aphid wing dimorphism. In the present study, the Sitobion avenae, a major pest on wheat, will be used as a model system to 1) upon the completion of proposed sequencing efforts, customized microarrays will be assembled to differentiate the expression profiles of winged and wingless aphid adults, including aphids treated by different environmental factors and individuals in each life stage. miRNA of interest resulted from the micoarray analyses will be validated by Northern Blot analyses; 2) Combining with the target gene prediction, 3 or 5 miRNAs of interest will be identified and validated; and 3) Ultimately, the biological functions of candidate miRNAs will be investigated using in vivo RNAi. This research will shed light on the molecular mechanism of aphid wing differentiation at both genetic and environmental levels. Subsequently, it will provide theoretical basis for the prediction and integrated management of phloem-feeding aphids in general, and S. avenae in particular.

昆虫翅的起源、发生、进化及其内在分子机制一直是人们关注和研究的热点。蚜虫是研究翅二型性的理想模式昆虫，可结合遗传因素和环境因素变化研究其翅分化的机制。本项目以重要谷物害虫--麦长管蚜Sitobion avenae为研究对象，期望从表观遗传因子miRNA角度研究调控其翅型分化的分子机制。具体研究内容为：1）利用自有的麦长管蚜miRNA文库制备基因芯片，比较不同环境因子刺激和不同发育阶段，有翅和无翅蚜中这些miRNAs的表达量变化，筛选有翅和无趐蚜中差异表达的miRNA，通过Northern blot 进一步验证；2）结合靶基因的预测，鉴定出3-5个在翅型分化中起重要作用的miRNA；3）利用miRNA干扰技术研究候选miRNA在麦蚜翅发育及分化过程中的功能，进而阐明miRNAs调控麦蚜翅型分化的分子机制。研究结果可为从根本上了解麦蚜的迁飞机理，为麦蚜的预测预报和综合防治提供理论依据。

在国家自然基金的资助下，本研究以麦长管蚜为研究对象，通过设定不同的环境因子，从表观遗传学角度对麦长管蚜翅型分化的生化和分子机理进行深入研究，目前各项研究工作均按照合同书顺利完成。取得的重要研究进展有三个方面，首先，利用体视显微镜和扫描电镜技术对麦长管蚜不同翅型、不同龄期若蚜和成蚜的形态测量学和外部形态特征进行研究，发现麦长管蚜1、2龄若蚜外部形态除了大小外无明显差别，表明无法通过外形来区分翅分化关键期的麦蚜翅型。接下来系统研究了主要环境因子对麦长管蚜成翅的影响，首次阐明去除共生物Buchnera使麦蚜种群当代和后代有翅蚜比例显著降低，重要的是解决了麦蚜前3个发育时期、两种翅型样本无法获取的难题。最终通过分析翅分化关键期差异表达miRNA，首次发现可导致麦长管蚜翅发育畸形的miRNA，该研究结果为麦蚜翅型分化的分子机制研究阐明提供必要的数据支持。综上所述，本研究从表观遗传学角度研究麦蚜翅型分化的生化和分子机制，研究结果为明确麦蚜的迁飞机制提供一定的理论依据，并且有助于从根本上了解麦蚜的迁飞机理，为麦蚜的监测预警和综合防治提供理论依据。