Characteristics of iron uptake in Ni‐tolerant mutant and wild‐type of ryegrass

Abstract

The uptake of ⁵⁹Fe(II)SO₄, ⁵⁹Fe(III) phytosiderophores and the release of phytosiderophores (PS) in a Ni‐tolerant mutant and its wild type of ryegrass (Lolium perenne L.) were examined. The results showed that the uptake rates of ⁵⁹Fe²⁺ in the mutant were about 2‐fold lower than those in the wild‐type independently of the Fe nutritional status (+/‐ Fe preculture) and Ni supply levels. In contrast, the uptake rates for ⁵⁹Fe(III)PS were higher in the mutant than in the wild‐type, particularly under Fe deficiency. The high Ni supply decreased ⁵⁹Fe(III)PS uptake rate by 40% for the wild‐type and by 20% for the mutant under Fe deficiency. However, the rate of PS release was significantly lower in the mutant than in the wild‐type. These results indicated that the relatively high sensitivity of Ni‐tolerant mutant to Fe deficiency is obviously due to a lower rate of Fe²⁺ uptake and PS release. Further studies are needed to understand the relationship between uptake and translocation of Ni and acquisition and translocation of Fe within the mutant.