Mobilisation of iron and manganese by plant-borne and synthetic metal chelators

Abstract

Phytosiderophores released by roots of iron-deficient grasses mobilise Fe, Zn, Mn and Cu in calcareous soils. Mobilisation of Fe, Zn and Cu can be explained as the chelation of these metal cations by phytosiderophores. Mobilisation of Mn could not be so explained because phytosiderophores have a much smaller affinity for Mn than for Fe, Cu and Zn. Model experiments have been made with freshly precipitated Fe(OH)₃ and different soils to study the mobilisation of iron and manganese by plant-borne chelating phytosiderophores, the synthetic metal chelators DTPA and the microbial metal chelator sulphonated ferrioxamine B (FOB). Compared with the synthetic chelator DTPA, the plant-borne chelating phytosiderophores mobilised Fe very efficiently, but no change was observed in the Mn mobilisation by phytosiderophores.

Different phytosiderophores, as well as the microbial metal chelator FOB, were used to compare the mobilisation of iron and manganese in a calcareous soil.