MODE OF ACTION OF GROWTH ENHANCES AND CHELATING COMPOUNDS ON THE UPTAKE OF CD AN

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The remediation of heavy metals from the environment using plants is a novel technology commonly termed phytoremediation. Many plants have shown the ability of uptake heavy metals, including lead and cadmium, from contaminated growth media. However, the addition of chelating agents such as EDTA has been shown to increase the uptake and translocation of both cadmium and lead in many different plant species. We have recently been investigating the use of growth promoters such as gibberlic acid, indolic-3-acetic acid, kinetine, 2,4-dichlorophenoxy acid, and glutathione, with mixtures of EDTA. We have observed that specific molar combinations of EDTA and IAA increase the uptake of lead in alfalfa plants by approximately 2800% over treatments with lead alone in the leaves of the plants. In addition, the use of equal molar concentrations of indole-3-acetic acid and EDTA increased the uptake of lead by 600% over the use of EDTA alone in the leaves of alfalfa plants. However, in the roots and stems of the alfalfa plants the uptake of lead was reduced when combinations of indole-3-acetic acid-EDTA were used. These results have much promise in producing a viable phytoremediation system. We plan to use XAS to understand the chemistry and subsequently, the mode of action that growth promoters/ enhancers have on the uptake and coordination of both lead and cadmium in live plants. XAS studies will provide us with a chemical understanding of this complex biochemical process of reducing the toxicity of the metals and at the same time increasing the translocation of metals through the plant.