Enhancement of lead uptake by alfalfa (Medicago sativa) using EDTA and a plant growth promotor

Phytoremediation is a novel cleanup technology for the removal of contaminants from polluted waters and soils. In phytoremediation, the plant uptake capability and the availability of the pollutant in the media are important. Here we show the results of a study on the combined effects of ethylenediaminetetraacetic acid (EDTA) and the phytohormone indole-3-acetic acid (IAA) on Pb uptake by Medicago, sativa (alfalfa). Plants were grown in hydroponics media containing a nutrient solution amended with Pb at 0.2 mM and different combinations of EDTA, and IAA. After 10 d of treatment, the Ph content in plant tissues was quantified using an Inductively Coupled Plasma Optical Emission Spectrometer (ICP/OES). The results showed that the combination of 100 mu M IAA/0.2 mM EDTA increased the Ph accumulation in leaves by about 2800% and by about 600%, as compared to Ph content in leaves of plants exposed to Pb alone and those cultivated with Pb/EDTA, respectively. These results indicate that non-metal hyperaccumulator plants could increase their hyperaccumulating potential without genetic manipulation. (C) 2005 Elsevier Ltd. All rights reserved.