Screening of a new candidate tree legume- Pithecellobium dulce (Roxb.) Benth., for lead remediation

A fast-growing, leguminous tree species- Pithecellobium dulce (Roxb.) Benth. , was screened in vitro against Pb-stress for the first time. In the current study, Pb toxicity affected the seedlings growth, lipid peroxidation, hydrogen peroxide production, antioxidant enzymes activity, proline content, and genomic template stability in a dose-dependent manner. The plant showed a high Pb tolerance, uptake and accumulation (> 2300 mg Kg −1 ). Citric acid application could mitigate Pb-stress in the seedlings exhibited by the examined morphological, biochemical, and molecular parameters, including remarkably enhanced Pb uptake by the roots . Citric acid addition to the Pb solution reduced lipid peroxidation and ROS production in the seedlings roots, stem, and leaves. Citric acid also induced the antioxidant enzymes activities in the seedlings that were reduced by Pb exposure. Citric acid-mediated recovery under Pb-stress was evidenced by the growth and development of the seedlings, higher chlorophyll pigments, lower proline content and maximum tolerance index. The Pb exposure altered the genomic template stability that was also recovered by citric acid. Thus, after further field studies, P. dulce with citric acid mitigation may prove suitable for Pb remediation from contaminated sites.