椰扁甲啮小蜂寄生介导的miRNA调控水椰八角铁甲蛹黑化的机制

Octodonta nipae is a serious invasive pest of palm plants in South China, and the endoparasitoid Tetrastichus brontispae is a natural enemy of this pest, which showed huge potential in biocontrol of O. nipae. The impairment of host humoral immunity such as melanization is one of the mechanisms for successful parasitism. miRNA plays key roles in regulation of gene expression at the post-transcriptional level adding a new layer of control to the complex pathways that exists in various biological processes such as immune response. It was shown that parasitism by T. brontispae had a significant effect on melanization response. In the present study, differential expression of host miRNA in response to parasitism will be examined by construction and sequencing of small RNA libraries from parasitized and naive pupae of O. nipae, and the miRNA involved in melanization pathways will be identified by integrating miRNA gene-target prediction algorithms with dual luciferase reporter assay, then the roles of the miRNA will be examined by injection of its mimic and inhibitor into the host pupae. The integrated results of this study will provide insights into the regulatory mechanisms of melanization by miRNA in response to parasitism. In addition, the analyses will offer an invaluable resource for O. nipae-T. brontispae interaction, and pave the way for the development of novel management strategies of O. nipae, such as utilizing the special miRNA.

水椰八角铁甲是危害我国南方棕榈科植物的重大外来入侵害虫，椰扁甲啮小蜂是其重要的寄生性天敌。干扰寄主的免疫如黑化是寄生蜂成功寄生的途径之一，miRNA可同时调控同一信号通路或多个信号通路中多个靶基因的表达，在基因转录后免疫调控中起着重要作用。本项目在前期研究明确椰扁甲啮小蜂寄生显著抑制寄主黑化反应的基础上，筛选寄生前后水椰八角铁甲中具差异表达的黑化相关的miRNA，鉴定明确miRNA调控黑化反应的相关通路，通过功能获得或缺失验证相关miRNA在调控水椰八角铁甲黑化反应中的功能，从表观遗传学角度揭示椰扁甲啮小蜂寄生介导的miRNA调控水椰八角铁甲蛹黑化反应的分子机制。研究结果有助于深入剖析椰扁甲啮小蜂与水椰八角铁甲的免疫互作，同时为有效地靶向miRNA开发新型害虫抑制剂防控水椰八角铁甲提供新的思路和途径。

水椰八角铁甲是危害我国南方棕榈科植物的重大外来入侵害虫，椰扁甲啮小蜂是其重要的寄生性天敌。干扰寄主的免疫如黑化是寄生蜂成功寄生的途径之一，miRNA可同时调控同一信号通路或多个信号通路中多个靶基因的表达，在基因转录后免疫调控中起着重要作用。本项目研究发现，水椰八角铁甲蛹期miRNA共有274个，其中新miRNA180个，已知miRNA94个；椰扁甲啮小蜂寄生后12、48和72h差异表达的miRNA的靶基因主要富集于lysosome和phagosome通路。水椰八角铁甲中存在两条黑化级联通路，OnSP8和OnPPAF1。OnPPO1在黑化级联反应中具有重要作用，OnSP8与OnPPAF1皆可直接作用于OnPPO1，OnSP8还可与大多数丝氨酸蛋白酶酶原形成复合物；Onserpin5和Onserpin1参与了反应中心复合物的形成，主要作为负调控因子参与丝氨酸蛋白酶作用。椰扁甲啮小蜂寄生介导的miR-281-3p和miR-182-5p参与调控黑化级联反应，其中miR-281-3p靶向OnPPO1，miR-182-5p靶向OnSPN1，且miRNA-281-3p和miRNA-182-5p影响椰扁甲啮小蜂的生长发育。上述研究结果有助于深入剖析椰扁甲啮小蜂与水椰八角铁甲的免疫互作，同时为有效地靶向miRNA开发新型害虫抑制剂防控水椰八角铁甲提供新的思路和途径。