Wolbachia介导的两近缘种茶尺蠖生殖隔离机制研究

Wolbachia can cause a number of reproductive alterations in its hosts though different approaches. Previous studies have shown that two closely related species of tea pests (Ectropis grisescens and Ectropis obliqua) with reproduction isolation in tea garden, give birth to generation F1 after cross-breeding; however, an abnormal F1 hybrid offspring with inability to produce fertile eggs through F1 self-crossing. A significant difference was observed in the prevalence of Wolbachia between the two species. That is an interesting phenomenon whether Wolbachia can induce reproduction isolation of two related species of tea looper. In the study, Wolbachia of tea looper, which collected from different areas, was tested by molecular markers of 16S rRNA and wsp. The strains of Wolbachia infected and no Wolbachia infected were cultivated by natural screening and antibiotic disposing. Cross-breeding experiments were designed between tea looper strains of Wolbachia infected and uninfected. Statistical analysis the number of eggs, hatchability and sex ratio of F1 hybrid offspring were analyzed to evaluate whether Wolbachia can induce reproduction isolation of two related species of tea looper. Further, the difference of mature sperms, between Wolbachia infected and uninfected, before- and after- mating, were compared to explore the mechanism of Wolbachia-induced reproduction isolation of two related species.

Wolbachia能够通过多种机制调节宿主昆虫的生殖行为。项目组前期研究发现茶园广泛分布的茶树主要食叶类害虫存在小茶尺蠖（Ectropis obliqua）和灰茶尺蛾（Ectropis grisescens）两近缘种，且种间可交配但无法续代，进一步分析两近缘种体内Wolbachia共生菌感染情况呈现明显差异。本研究拟通过采用16S rRNA和wsp分子标记检测两近缘种茶尺蠖不同野生种群中Wolbachia的感染规律；进一步通过自然筛选和抗生素处理等方式建立两近缘种茶尺蠖感染Wolbachia与未感染Wolbachia的纯合品系。将两近缘种茶尺蠖感染与未感染Wolbachia的个体进行种间杂交和种内自交，检测后代产卵率、性比及成活率。同时采用蛋白组学方法分析感染和未感染Wolbachia雄虫精子和精液蛋白在交配前后的差异，探索Wolbachia介导两近缘种茶尺蠖生殖隔离机制。

小茶尺蠖和灰茶尺蛾是我国茶园中最重要的两近缘种茶树害虫，二者外形相似、生态位高度重叠。二者能够交配并能够产生不可育的后代，表明二者存在生殖隔离现象。Wolbachia是广泛存在于节肢动物体内的共生菌，它能通过多种方式调控寄主间的生殖作用。进一步研究显示茶尺蠖两近缘种共生菌Wolbachia感染情况存在明显差异，这是否意味着共生菌Wolbachia 参与了两近缘种间生殖隔离的调控？本项目针对这一科学问题展开了研究。研究内容包括三个方面：(1)两近缘种茶尺蠖Wolbachia感染情况及传递规律。(2)Wolbachia介导的两近缘种茶尺蠖生殖隔离作用。(3)Wolbachia感染对两近缘种茶尺蠖精子和精液蛋白的影响。研究成果主要包括：a.明确了灰茶尺蛾携带沃尔巴克菌而小茶尺蠖不携带。b.通过抗生素处理建立了不携带Wolbachia的灰茶尺蛾种群。c.揭示了Wolbachia能够通过对雄虫精子蛋白的修饰来调控茶尺蠖两近缘种杂交卵的孵化，从而介导茶尺蠖两近缘种的生殖隔离。本研究为进一步研究Wolbachia参与两近缘种茶尺蠖分化提供理论基础，并将为Wolbachia介导的物种进化与分化提供一个新的案例，具有重要的科学和现实意义。