前期研究发现miR-308-3p靶向PGRP-LB基因介导了小菜蛾抗菌肽的表达，但调控机制不清楚。本项目拟用1、CRISPR/Cas9敲除Imd和PGRP-LB基因，RNA-Seq结合RT-qPCR检测小菜蛾抗菌肽基因的表达差异，阐明PGRP-LB介导Imd通路调控抗菌肽表达的功能；2、荧光素酶系统和RNA免疫沉淀明确miR-308-3p和PGRP-LB靶向关系，利用超表达或抑制miR-308-3p活性的方法结合CRISPR/Cas9，阐明miR-308-3p靶向PGRP-LB介导Imd通路调控小菜蛾抗菌肽表达的分子机制。研究结果将有助于我们深入了解miRNA参与宿主免疫反应的分子机制，为害虫抗菌肽表达调控的系统阐明提供新的理论基础和支撑；并为以害虫免疫系统为靶标体系，阻断害虫免疫信号传导的微生物杀虫剂的开发奠定理论基础，以期为害虫的生物防治提供新的理论和途径。

Our previous studies have found that miR-308-3p targeting PGRP-LB gene regulates the expression of antimicrobial peptides in Plutella xylostella, but the molecular regulatory mechanism is not clear. In this project, we intend to use CRISPR/Cas9 to knock out Imd and PGRP-LB in DNA level, and use RNA-Seq and qRT-PCR to clarify their function in regulation of the expression of antimicrobial peptides. Dual Luciferase system and RNA immunoprecipitation (RIP) will be used to clearly define the targeting relationships between miR-308-3p and PGRP-LB, subsequently, the molecular mechanism of miR-308-3p targeting PGRP-LB to regulate the expression of antimicrobial peptides will be elucidated by integrated analsis of CRISPR/Cas9 and overexpression or inhibition of miR-308-3p. The results of this study will help us further understand the molecular mechanism of miRNA involved in host immune response, and provide a new theoretical basis and support for the systematic elucidation of the regulation of insect antimicrobial peptides. It also lays a theoretical foundation for the development of microbial insecticides that target the immune system of pests and block the transmission of immune signals, so as to provide a new theory and approach for the biological control of pests.