Mössbauer study of iron uptake in cucumber root

Abstract

57Fe Mossbauer spectroscopy was used to study the uptake and distribution of iron in the root of cucumber plants grown in iron-deficient modified Hoagland nutrient solution and put into iron-containing solution with 10 μM Fe citrate enriched with 57Fe (90%) only before harvesting. The Mossbauer spectra of the frozen roots exhibited two Fe3+ components with typical average Mossbauer parameters of δ = 0.5 mm s−1, Δ = 0.46 mm s−1 and δ = 0.5 mm s−1, Δ = 1.2 mm s−1 at 78 K and the presence of an Fe2+ doublet, assigned to the ferrous hexaaqua complex. This finding gives a direct evidence for the existence of Fe2+ ions produced via root-associated reduction according to the mechanism proposed for iron uptake for dicotyledonous plants. Monotonous changes in the relative content of the components were found with the time period of iron supply. The Mossbauer results are interpreted in terms of iron uptake and transport through the cell wall and membranes.