Lead bioaccumulation in Acacia farnesiana and its effect on lipid peroxidation and glutathione production

Phytoremediation offers a cheap, efficient and environmentally friendly option for cleaning sites contaminated with toxic elements. However, there is a need to find new plant species for phytoremediation and to understand the mechanisms involved in processes such as tolerance, accumulation, exclusion and metabolism of toxic metals in plants. Thereby, in this study, the ability of Acacia farnesiana (L.) Willd to tolerate and accumulate lead was analyzed. Seedlings grown in vitro with 250 and 500 mg Pb 2+ L −1 showed an increase in their growth, achieving tolerance indexes close to 100%. In seedlings exposed to 1,000 mg Pb 2+ L −1 , growth was strongly inhibited, finding an effective concentration 50% (EC 50 ) from 720 to 766 mg Pb 2+ L −1 . A. farnesiana accumulated ≥80% of the Pb 2+ in roots (up to 51,928 mg kg −1 of air-dried tissue) in seedlings exposed to 1,000 mg Pb 2+ L −1 , with high bioconcentration (>8.5) and low translocation (≤0.03) factors. These results indicate the suitability of A. farnesiana for lead-phytostabilization purposes. Lead concentrations below 500 mg L −1 had no significant effect on lipid peroxidation and enhanced the glutathione content, suggesting that the ability of A. farnesiana to withstand the Pb-induced oxidative stress could be related to glutathione metabolism.