芥菜型油菜具有富集镉的特性而在镉污染土壤修复中极具应用价值，但也导致了其作为油料作物使镉通过食物链被人类摄取的风险，因此镉在油菜中积累的机制值得深入研究。已有研究表明microRNA在植物镉积累中发挥调控作用，这为通过调控microRNA或其靶基因而改良作物镉积累性状提供了一条重要的新途径。在前期工作中我们通过测序鉴定了芥菜型油菜镉胁迫响应microRNA，并在芥菜型油菜镉高积累自交系和镉低积累自交系进行了定量PCR表达差异分析，筛选了镉积累相关的候选microRNA。本项目将克隆并验证候选microRNA的靶基因，构建候选microRNA及其靶基因的过表达载体并转化芥菜型油菜，通过分析转基因材料镉积累性状，鉴定出镉积累相关的microRNA并阐明其功能。研究结果将初步阐明microRNA调控芥菜型油菜镉积累的分子机理，为油菜镉积累性状的分子育种奠定理论基础。

As a cadmium hyperaccumulator, Brassica juncea possesses great application potential for phytoremediation of cadmium contaminated soil. But as an important oil seed crop，it also results in hazards of human health through transferring Cd to human food chain. Therefore, it’s necessary to investigating the mechanisms of Cd accumulation in Brassica juncea plants. Previous studies have indicated that microRNAs play important roles in the regulation of Cd accumulation in plants, which provides an important new way to control crop Cd accumulation by regulating microRNAs or their target genes. In previous work, we identified Cd stress responsive microRNAs in Brassica juncea by small RNA sequencing, and selected some microRNAs as cadmium accumulation related microRNA candidates via comparative analysis of expressing difference between a cadmium high accumulation inbred line and a cadmium low accumulation inbred line. In this projects, we will clone and validate microRNA candidates and their target genes, then construct recombinant expression vectors and transform them into Brassica juncea. By comparative analysis of cadmium accumulation properties between transgenic plants and control plants, the functions of candidate microRNAs and their target genes in regulating cadmium accumulation will be elucidated. This project is expected to shed light on the roles of microRNAs in cadmium accumulation, and lay the foundation of genetic improvement of Brassica juncea.