Investigation of ferric iron reduction on the root surfaces of common reeds using an EDTA‐BPDS method

Abstract

Graminaceous species usually response to iron (Fe) stress by release of phytosiderophores. But, it remains unclear where Fe³⁺ is reduced after being chelated with phytosidoerophores. In this investigation, dynamic concentration of Fe²⁺ and Fe³⁺ on root surfaces of common reeds [Phragmites australis (Cav.) Trin ex Steudel] was observed using an EDTA‐BPDS (disodium ethylenediamine‐N, N, N’, N'‐tetra acetate and disodiumbathophenanthroline disulfonate) method. The dynamics of Fe²⁺, Fe³⁺, and total Fe accumulation on 5 cm tips of roots can be respectively described (in umole g^‐1 fresh root weight, FRW) as: [Fe²⁺]=0.0949t^0.21, [Fe³⁺]=17.9Exp(‐4.96310r^0.086) and [Fe]=0.1964t^0.28 when the roots were placed in a 0.1 mM ferric citrate solution. Based on the derivatives obtained from the above regression equationss, the accumulation rate (in μmole h^‐1 g^‐1 FRW) of Fe²⁺ on the roots was higher than that of Fe³⁺ during the initial few (<5) minutes, but decreased faster than that of Fe³⁺. The Fe³⁺ reduction was also observed in the solution after removing the roots. The reduction rate was 30 times lower than that in the solution with the roots. The results suggested that the reducing power is associated with reductase on the root surfaces.

Notes

The work was carried out at the Department of Soil, Crop and Atmospheric Sciences, Cornell University, Ithaca, NY 14853.