OsNRAMP5, a major player for constitutive iron and manganese uptake in rice

Abstract

Manganese (Mn) and iron (Fe) are essential mineral micronutrients for plants and their deficiency and or toxicity represents a serious agricultural problem. In rice the information about genes involved in Mn uptake from soil is scarce. Recently, we showed that OsNRAMP5 is a plasma membrane protein involved in Mn and Fe transport. The concentration of Mn in roots, shoots and xylem sap of OsNRAMP5 RNAi (OsNRAMP5i) plants was significantly reduced compared with WT plants. The expression of OsNRAMP5 is not controlled by Fe deficiency in root and was also observed in pistil, ovary, lemma and palea. These data show that rice would utilize OsNRAMP5 for constitutive Fe and Mn uptake, while OsNRAMP5 would also play a role in Fe and Mn transport during flowering and seed development.

Figure 1. Expression of OsNRAMP5 in root, pistil, root, ovary, palea and lemma. Normalized expression of OsNRAMP5 transporters in (A) roots at 27 and 76 d after transplantation, (B) pistil at 5–10, 10–14 and 14–18 mm panicle (D) ovary at 1, 3, 5 and 7 d after flowering (D) lemma at 1.5–2.0, 4.0–5.0 and 7.0 mm floret (E) palea at 1.5–2.0, 4.0–5.0 and 7.0 mm floret. Error bars represent SD (n = 3).

Figure 2. Characterization of OsNRAMP5i and OsNRAMP5 OX lines grown under control or Mn-deficient conditions. Mn concentrations of root (A) and shoot (B) of wild type, OsNRAMP5i (T5i-1, T5i-2) and OsNRAMP5OX (OX1, OX2) plants (cultivar Tsukinohikari) grown under control conditions or Mn-deficient conditions. Fe concentrations of root (C) and shoot (D) of wild type, OsNRAMP5i (T5i-1, T5i-2) and OsNRAMP5OX (OX1, OX2) plants (cultivar Tsukinohikari) grown under control conditions or Mn-deficient conditions. Error bars represent the SD. Columns bars followed by different letters are statistically different according to Student-Newman-Keuls (SNK) test (p < 0.05); n = 3.