Toxicity versus accumulation for barley plants exposed to copper in the presence of metal buffers: Progress towards development of a terrestrial biotic ligand model

• DOI: 10.1897/06-641r.1
• Publication Date: 2007-10-17T22:17:21Z
• Authors: Paula M.C. Antunes; Beverley A. Hale; Adam C. Ryan
• Keywords: Nitrilotriacetic acid; Biotic Ligand Model; Copper toxicity; Ethylenediaminetetraacetic acid; Elongation; Phytotoxicity; Metal Toxicity

Abstract Development of a terrestrial biotic ligand model (TBLM) for higher plants requires root‐Cu accumulation value that corresponds to the 50% inhibitory concentration (IC50). However, it is not yet known which two previously reported Cubinding ligands on root associated with Cu toxicity. The aim present study was therefore investigate relationship between binding each group and toxicity, so key toxicological site could be identified. To obtain toxicity data were biased by limited supply root, 2‐d‐old barley seedlings exposed 48 h range free ion activities (i.e., {Cu 2+ }) in simple exposure media buffered nitrilotriacetic acid (NTA) or ethylenediaminetetraacetic (EDTA). Comparison amount predicted root‐bound (calculated aqueous geochemical program PHREEQC) elongation showed likely resulted from low‐affinity ligands, as high‐affinity approximately 99% saturated when reduction first observed. For both NTA‐ EDTA‐buffered } solutions, corresponding IC50 80 μg/g dry weight, similar obtained previous work wheat. linear bound percent growth inhibition suggests this will robust predictor incorporated into TBLM, applied varied scenarios. solutions used here, TBLM‐predicted measured values statistically indistinguishable.