CSIR-National Botanical Research Institute (CSIR-NBRI), Rana Pratap Marg, Lucknow, 226001, India.
Plant Cell Environ. 2014 Jan;37(1):140-52. doi: 10.1111/pce.12138. Epub 2013 Jun 25.
Irrigation of paddy fields to arsenic (As) containing groundwater leads to As accumulation in rice grains and causes serious health risk to the people worldwide. To reduce As intake via consumption of contaminated rice grain, identification of the mechanisms for As accumulation and detoxification in rice is a prerequisite. Herein, we report involvement of a member of rice NRAMP (Natural Resistance-Associated Macrophage Protein) transporter, OsNRAMP1, in As, in addition to cadmium (Cd), accumulation through expression in yeast and Arabidopsis. Expression of OsNRAMP1 in yeast mutant (fet3fet4) rescued iron (Fe) uptake and exhibited enhanced accumulation of As and Cd. Expression of OsNRAMP1 in Arabidopsis provided tolerance with enhanced As and Cd accumulation in root and shoot. Cellular localization revealed that OsNRAMP1 resides on plasma membrane of endodermis and pericycle cells and may assist in xylem loading for root to shoot mobilization. This is the first report demonstrating role of NRAMP in xylem mediated loading and enhanced accumulation of As and Cd in plants. We propose that genetic modification of OsNRAMP1 in rice might be helpful in developing rice with low As and Cd content in grain and minimize the risk of food chain contamination to these toxic metals.
灌溉含砷地下水到稻田中会导致砷在稻米中积累，给全世界的人们带来严重的健康风险。为了减少通过食用受污染的大米摄入砷，鉴定水稻中砷积累和解毒的机制是先决条件。在此，我们报告了水稻 NRAMP（天然抗性相关巨噬细胞蛋白）转运蛋白的一个成员 OsNRAMP1 参与了除镉（Cd）以外的砷积累，通过在酵母和拟南芥中的表达。在酵母突变体（fet3fet4）中表达 OsNRAMP1 可恢复铁（Fe）的摄取，并表现出增强的砷和 Cd 积累。在拟南芥中表达 OsNRAMP1 提供了耐受性，并增强了根和茎中的砷和 Cd 积累。细胞定位表明 OsNRAMP1 位于内皮层和周细胞的质膜上，可能有助于木质部加载，以便将根到茎的移动。这是第一个证明 NRAMP 在木质部介导的加载和增强植物中砷和 Cd 积累中的作用的报告。我们提出，在水稻中对 OsNRAMP1 进行基因修饰可能有助于开发砷和 Cd 含量低的稻米，并最大限度地减少食物链对这些有毒金属的污染风险。
