OsNRAMP1 transporter contributes to cadmium and manganese uptake in rice

• Published in: Plant, cell and environment Vol. 43; no. 10; pp. 2476 - 2491
• Main Authors: Chang, Jia‐Dong, Huang, Sheng, Yamaji, Naoki, Zhang, Wenwen, Ma, Jian Feng, Zhao, Fang‐Jie
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.10.2020; Wiley Subscription Services, Inc
• Subjects: Arsenic; Cadmium; Cadmium - metabolism; Cation Transport Proteins - metabolism; environment; food safety; Gene Knockdown Techniques; Heavy metals; Iron; Iron deficiency; Leaves; Macrophages; Manganese; Manganese - metabolism; Membrane proteins; Mesophyll; metal transporter; Microorganisms, Genetically-Modified; nutrient deficiencies; Oryza - metabolism; OsNRAMP1; Plant Proteins - metabolism; Plants, Genetically Modified; Protein transport; Proteins; Rice; Saccharomyces cerevisiae; Shoots; toxicity; Transcriptome; Yeast; yeasts; OsNRAMP1; food safety; cadmium; rice; manganese; metal transporter
• ISSN: 0140-7791; 1365-3040; 1365-3040
• DOI: 10.1111/pce.13843

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. Rice is the major dietary source of the toxic metal cadmium. Understand how rice takes up Cd is important. Two previous studies showed that OsNRAMP1 could transport iron (Fe), Cd and arsenic (As) in heterologous yeast assays, but its in planta function remains unknown. Here, we functionally characterize OsNRAMP1 and show that the transporter contributes significantly to the uptake of Cd and Mn in rice, but not the uptake of Fe or As. OsNRAMP1 and OsNRAMP5 play similar but non‐redundant functions. Our study sheds light on the mechanisms of Cd and Mn uptake by rice.