Efficient cadmium uptake and accumulation in pokeweed (Phytolacca americana L.) associated with its potential for phytoremediation of cadmium-polluted soils

Abstract

Background and aims

Phytoremediation is a sustainable strategy for remediating cadmium (Cd)- contaminated soils; however, the limited availability of ideal Cd hyperaccumulator plants remains a significant challenge. Initially recognized as a manganese (Mn) hyperaccumulator, pokeweed (Phytolacca americana L.) has also demonstrated the ability to accumulate Cd. This study aims to characterize Cd accumulation in pokeweed from a physiological perspective and evaluate its potential for Cd remediation.

Methods

We assessed the Cd accumulation characteristics of pokeweed through comprehensive physiological experiments and investigated Cd cellular distribution in roots and leafstalks using a Cd molecular probe. Additionally, we compared its remediation potential with that of rice varieties, including the wild-type T-65 and the Cd hyperaccumulating mutant TCM-213.

Results

Pokeweed demonstrated remarkable Cd accumulation in its shoots, reaching concentrations as high as 1,239 mg·kg⁻¹. This plant exhibits both high Cd uptake efficiency and effective xylem loading capacity. Cd accumulates predominantly in the leaves, with its distribution largely driven by transpiration. At the cellular level, Cd primarily localizes in the endodermis and xylem vascular bundle cells of roots, as well as in the epidermis and xylem vascular bundle cells of older leafstalks. Furthermore, pokeweed has a purification rate of 35%, which is significantly higher than that of TCM-213.

Conclusions

These findings establish pokeweed as a promising Cd hyperaccumulator, highlighting its potential application in the remediation of Cd-contaminated soils.