Evaluation of Lead Toxicity in Erica andevalensis as an Alternative Species for Revegetation of Contaminated Soils

Abstract

Although revegetation using native flora is a low cost way to stabilize soil and restore the landscape contaminated with metals, little is known regarding the Pb-tolerance of many of these species. For this purpose, we evaluated the tolerance of Erica andevalensis to Pb by growing plants in nutrient solutions with increasing concentrations of Pb (up to 100 μM). Plant growth and different physiological parameters were determined to ascertain tolerance to metal stress. Additionally, an electron microscopy study coupled with EDX-analysis was performed to get clues on the Pb uptake and translocation from roots into stem and leaves. The LOEC (the lowest observed effect concentration) of Pb was 40 μM while the IC50 (inhibition concentration) was 80 μM Pb. Chemical analysis revealed a root>stem>leaf accumulation pattern. There was a severe reduction in fresh biomass and chlorophyll concentration at the highest Pb dose. The SEM-EDX study indicated that Pb was mostly located in root epidermal tissues. The blockage of Pb on the root probably avoided its toxic effects by limiting Pb transport to other tissues.

KEY WORDS:

• native plant
• mining
• phytostabilization
• Pb-exclusion
• Pb-localization
• SEM-EDX

ACKNOWLEDGMENTS

This work was supported by Fundation Ramón Areces. The authors thank the techniques from the Green house of Sevilla University for their technical assistance in plant cultivation and S. Giordano (University Federico II, Naples, Italy) for her assistance in microscopy study.