Phytosiderophores Influence on Cadmium Mobilization and Uptake by Wheat and Barley Plants

• Published in: Journal of environmental quality Vol. 30; no. 6; pp. 2091 - 2098
• Main Authors: Shenker, M., Fan, T.W.‐M., Crowley, D.E.
• Format: Journal Article
• Language: English
• Published: Madison American Society of Agronomy, Crop Science Society of America, Soil Science Society 01.11.2001; Crop Science Society of America; American Society of Agronomy
• Subjects: Anthropogenic factors; Applied sciences; Barley; Biological and medical sciences; Biological Availability; Biotechnology; Cadmium; Cadmium - pharmacokinetics; Chelates; Chelating Agents - chemistry; Chelation; Decontamination. Miscellaneous; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Hordeum - physiology; Industrial applications and implications. Economical aspects; Metals; Miscellaneous; Plant extracts; Plant Roots - physiology; Plant Structures; Plant tissues; Pollution; Pollution, environment geology; Rhizosphere; Roots; Soil and sediments pollution; Soil Pollutants - pharmacokinetics; Soil pollution; Soil solution; Tissue Distribution; Triticum - physiology; Wheat; Monocotyledones; HEDTA; In situ; Soil pollution; Competitive fixation; Phytosiderophore; Decontamination; Siderophore; Gramineae; Angiospermae; Bioremediation; Cadmium; Complexation; Hordeum vulgare; Uptake; Heavy metal; Phytoremediation; Mobilization; Synthetic product; Medium effect; Chelating agent; Spermatophyta; Biological accumulation; Performance; Triticum aestivum
• ISSN: 0047-2425; 1537-2537
• DOI: 10.2134/jeq2001.2091

ABSTRACT A constant anthropogenic release of cadmium to the environment has resulted in a continuous buildup of Cd in soils. Uptake and accumulation of Cd in plant tissue and in grains may lead to food chain transfer to humans. Application of synthetic chelates was suggested to increase metal mobilization and facilitate phytoextraction as a means for the remediation of metal‐polluted soils. However, most of the chelate‐extracted metal may be leached rather than mobilized to plant roots. In contrast to the synthetic chelates added to soils, plant‐produced chelators called phytosiderophores (PS) are excreted directly to the rhizosphere. Previous studies have shown that PS facilitate uptake of Zn and Fe by graminaceous plants. In this study, a two‐step PS mediation of Cd uptake was hypothesized: (i) extraction and chelation in the soil solution, and (ii) delivery of the chelated Cd to the uptake system of the plant. We examined Cd extraction by PS, the synthetic chelate HEDTA [N‐(2‐hydroxyethyl)‐ethylenediamine‐triacetic acid], and a fungal siderophore rhizoferrin from solid‐phase Cd phosphate at pH 7.3 with and without Fe competition in the presence of Ca and Mg as additional competing metals. While rhizoferrin did not extract Cd, PS and HEDTA did extract Cd even in the presence of Fe. Yet, uptake of Cd by wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) plants was not significantly influenced by Fe stress, but instead was controlled primarily by Cd2+ activity in solution. These results suggest that even though Cd may be mobilized by PS, there is no significant uptake of the Cd–PS complex by the plant roots.