Mössbauer study of iron uptake in cucumber root

⁵⁷Fe Mössbauer 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 Mössbauer spectra of the frozen roots exhibited two Fe³⁺ components with typical average Mössbauer 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 Mössbauer results are interpreted in terms of iron uptake and transport through the cell wall and membranes.