元江普通野生稻及渗入系镉低积累机理研究

Breeding low-Cd accumulation rice varieties is the effective way to solve the cadmium pollution in cultivated rice. Genetic diversity of rice is the basis for the selection of low accumulation varieties of cadmium. As the wild rice is rich in gentic diversity, it is the best way to broaden its genetic background by introducing wild rice genome. In our previous work, we found that Cd accumulation range of descendants of introgression line of Yuanjiang wild rice was as high as 54. And some low-Cd accumulation rice strains(<0.10mg/kg) whose female parent is just the opposite (0.35mg/kg) have also been found .Thus we supposed that there exists Cd accumulation-related genes in Yuanjiang wild rice. In this project, Cd contents in seeds of descendants of introgression line of Yuanjiang wild rice planted in intermediate contaminated paddy fields will be determined to select low or high-Cd accumulation rice. By technique of RNA-Seq and two-dimensional electrophoresis, the differentially expressed genes and differentially protein could be analyzed. The metabolize pathway and low accumulation genes related to Cd accumulation could also be obtained and finally the expression pattern and regulation model of these genes will be explored. It will provide the theoretical basis and the intermediate materials for the cloning of the following related genes and breeding of low-Cd accumulation rice varieties.

培育镉低积累水稻品种是解决稻米镉污染的有效途径。水稻遗传多样性是选育镉低积累品种的基础，野生稻具有丰富的遗传多样性，引入野生稻资源是拓宽水稻遗传遗传多样性的最佳途径。前期工作中我们发现元江普通野生稻渗入系后代籽粒镉积累极差达54倍，存在籽粒镉低积累株系(<0.10mg/kg)，而母本为非镉低积累材料(0.35mg/kg)，因此，元江普通野生稻可能存在与镉低积累相关基因。本项目拟通过对种植于中度污染大田的元江普通野生稻渗入系籽粒的镉含量进行测定，筛选出镉低积累、镉高积累材料，采用 RNA-Seq和蛋白质双向电泳对差异表达基因和差异蛋白进行分析，从而获得与镉积累相关的代谢通路及低积累基因，挖掘该基因表达和调控模式，为后续相关基因的克隆和低镉水稻品种选育提供中间材料及理论依据。

稻米镉污染是我国粮食安全急需解决的问题。明确水稻籽粒镉积累机理，选育低镉水稻品种是解决这一问题的关键。本项目从元江普通野生稻渗入系中筛选出籽粒低/高镉株系，分析低/高镉株系各器官镉分布特征、镉的亚细胞分布特点及生育期镉含量的动态变化，研究镉胁迫下，低/高株系转录组、蛋白组对镉的响应及调控机理。先后在田间和温室条件下开展试验，获得以下结果：1. 从120份元江普通野生稻渗入系株系中筛选出54份低镉株系及3份高镉株系，研究发现渗入系籽粒镉含量与产量及粒型、粒厚、千粒重、结实率成显著正相关。2. 低/高镉株系镉分布为根＞茎＞叶＞谷壳＞籽粒，高镉株系的根、谷壳、籽粒Cd 含量均显著高于低镉株系；镉亚细胞分布为细胞壁＞可溶部分＞细胞器。低/高镉株系动态变化研究发现灌浆期后低镉株系GJ91茎叶镉含量高于其它株系，这表明高镉株系对镉的吸收及转运到籽粒能力高于低镉株系，而低镉株系GJ91能将转运到地上部的镉大量储存在茎叶内，降低籽粒镉含量。3. 转录组及蛋白质研究：镉胁迫下，低/高镉株系茎、叶共产生9524个DEGs，其中6408个基因注释到27个二级功能分类，发现5类基因可能与镉转运积累相关，并鉴定出与镉相关的谷胱甘肽-s-转运酶（GSTU6）在低镉株系茎叶中大量上调表达，而在高镉株系内大量下调表达，也证实了田间低镉株系GJ91茎叶镉含量为什么高于高镉株系。低/高镉株系茎、叶共定量了147个差异蛋白，上调89 个，下调58 个。发现苯丙烷生物合成途径蛋白可能与镉积累相关。本研究结果可为低镉水稻品种选育提供中间材料，也为水稻低镉机理提供理论基础。