水稻是我国最主要的粮食作物，也是一种对重金属镉 (Cd) 富集相对较高的作物，降低水稻对镉的吸收和累积是提高我国稻米质量安全的关键之一，然而目前对水稻镉积累的遗传机理和相关分子作用机制还是缺乏深入了解。本项目拟以籼稻9311 EMS诱变筛选到的镉低积累突变体lcd (low cadmium) 为材料，通过苗期水培镉处理，对lcd突变体镉低积累特性形成的生理生态特征进行分析研究；在此基础上，以lcd突变体和粳稻日本晴、台中65杂交构建的F2群体为材料，采用图位克隆技术分离lcd候选基因；最后，克隆候选基因并构建候选基因的互补表达载体、沉默表达载体、Promoter-GUS和lcd-EGFP融合表达载体，对候选基因进行功能验证，初步阐明水稻镉低积累的遗传机理和分子作用机制，为今后进一步通过分子标记辅助育种等手段来培育低镉水稻新品种、提高我国粮食质量安全提供理论依据。

Rice (Oryza sativa L.), as the most important food crop in China, is known to be strong cadmium (Cd) accumulator. Identification of rice cultivars with low Cd-accumulating abilities is a novel approach towards minimizing our dietary Cd intake, but little is known about the genetic and molecular mechanisms underlying Cd translocation and accumulation in rice plants. In this study, a low cadmium (lcd) mutant was isolated from EMS-generated rice mutant library (Oryza sativa L. indica, cv. 9311). Phenotypic and physiological characterization of the wild-type (WT) and mutant under Cd stress were investigated under solution culture. For the positional cloning of lcd gene, two F2 populations derived from rice inter-subspecific crosses, the lcd mutant/ japonica Nipponbare and the lcd mutant/ japonica Taizhong65 were constructed to isolate the lcd candidate genes by map-based cloning. The functions of the candidate genes were further validated by construction of complementary vector, RNAi vector, Promoter-GUS fusion vector and lcd-EGFP fusion vector of the candidate genes. These results will preliminarily illustrate the genetic and molecular mechanisms underlying Cd translocation and accumulation in rice plants, and provide a theoretical foundation for breeding of low Cd accumulation rice varieties and improving food safety in Cd-contaminated soils.