Rice is a major dietary source of the toxic metal, cadmium (Cd). Previous studies reported that the rice transporter, OsNRAMP1, (Natural resistance‐associated macrophage protein 1) could transport iron (Fe), Cd and arsenic (As) in heterologous yeast assays. However, the in planta function of OsNRAMP1 remains unknown. Here, we showed that OsNRAMP1 was able to transport Cd and manganese (Mn) when expressed in yeast, but did not transport Fe or As. OsNRAMP1 was mainly expressed in roots and leaves and encoded a plasma membrane‐localized protein. OsNRAMP1 expression was induced by Cd treatment and Fe deficiency. Immunostaining showed that OsNRAMP1 was localized in all root cells, except the central vasculature, and in leaf mesophyll cells. The knockout of OsNRAMP1 resulted in significant decreases in root uptake of Cd and Mn and their accumulation in rice shoots and grains, and increased sensitivity to Mn deficiency. The knockout of OsNRAMP1 had smaller effects on Cd and Mn uptake than knockout of OsNRAMP5, while knockout of both genes resulted in large decreases in the uptake of the two metals. Taken together, OsNRAMP1 contributes significantly to the uptake of Mn and Cd in rice, and the functions of OsNRAMP1 and OsNRAMP5 are similar but not redundant.

中文翻译：

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OsNRAMP1转运蛋白有助于水稻中镉和锰的吸收。

大米是有毒金属镉（Cd）的主要饮食来源。先前的研究报道，在异源酵母分析中，水稻转运蛋白OsNRAMP1（与自然抗性相关的巨噬细胞蛋白1）可以转运铁（Fe），镉和砷（As）。但是，OsNRAMP1的植物内功能仍然未知。在这里，我们表明OsNRAMP1在酵母中表达时能够转运Cd和锰（Mn），但不转运Fe或As。OsNRAMP1主要在根和叶中表达，并编码质膜定位蛋白。镉处理和铁缺乏诱导了OsNRAMP1的表达。免疫染色显示，OsNRAMP1位于除中央脉管系统外的所有根细胞和叶肉细胞中。淘汰赛OsNRAMP1显着降低了Cd和Mn的根吸收量以及它们在稻芽和谷粒中的积累，并增加了对Mn缺乏的敏感性。与敲除OsNRAMP5相比，敲除OsNRAMP1对Cd和Mn的吸收影响较小，而敲除这两个基因均会导致两种金属的吸收大大降低。两者合计，OsNRAMP1显着促进水稻中Mn和Cd的吸收，OsNRAMP1和OsNRAMP5的功能相似但并非多余。