Cadmium toxicity to barley (Hordeum vulgare) as affected by varying Fe nutritional status

The interference between Fe nutrition and Cd toxicity was investigated in barley seedlings grown in hydroponic culture. Barley employs strategy-II of plant Fe acquisition, i.e. secretion of phytosiderophores and uptake of PS-Fe complex. Nevertheless, excess Fe antagonised Cd accumulation and vice versa as reflected in growth and various biochemical parameters including thiols suggesting common transport mechanisms for uptake and also distribution of the two elements in strategy-II plants. Although the pathways of Cd and Fe toxicity induction are primarily different, oxidative stress as indicated by malondialdehyde equivalents and catalase activity was induced by both Cd and Fe. Again, at elevated Fe concentrations, the Cd-induced additional activation was decreased or absent. The antagonistic effect between Fe and Cd was verified at the level of gene expression. (C) 2004 Elsevier Ireland Ltd. All rights reserved.