AhNRAMP1 Enhances Manganese and Zinc Uptake in Plants

Abstract

Manganese (Mn) and zinc (Zn) play essential roles in plants. Members of the natural resistance-associated macrophage protein (NRAMP) family transport divalent metal ions. In this research, the function of peanut (<i>Arachis hypogaea</i> L.) AhNRAMP1 in transporting Mn and Zn, as well as its potential for iron(Fe) and Zn biofortification was examined. <i>AhNRAMP1</i> transcription was strongly induced by Mn- or Zn-deficiency in roots and stems of peanut. Yeast complementation assays suggested that <i>AhNRAMP1</i> encoded a functional Mn and Zn transporter. Exogenous expression of <i>AhNRAMP1</i> in tobacco and rice enhanced Mn or Zn concentrations, improving tolerance to Mn or Zn deficiency. With higher Mn concentration, transgenic plants exhibited inhibited growth under Mn excess condition; similar results were obtained under excessive Zn treatment. <i>AhNRAMP1</i> expression increased biomass in transgenic tobacco and rice, as well as yield in transgenic rice grown on calcareous soil. Compared with non-transformed (NT) plants, Fe and Zn concentrations were elevated whereas concentrations of Mn, copper (Cu), and cadmium (Cd) were not enhanced. These results revealed that <i>AhNRAMP1</i> contributes to Mn and Zn transport in plants and may be a candidate gene for Fe and Zn biofortification.