Cadmium hyperaccumulation and translocation in Impatiens glandulifera: From foe to friend?

Abstract

The use of phytoremediation to sustainably recover areas contaminated by toxic heavy metals such as cadmium (Cd) has been made feasible since the discovery of hyperaccumulator plants. This study examines the potential of the invasive Impatiens glandulifera for phytoremediation propensity of Cd. In these experiments, the plants were exposed to and tested for Cd accumulation; the propensity to accumulate other heavy metals, such as Zinc, was not investigated. The efficacy of phytoaccumulation was assessed over two trials (Cd concentrations of 20 mg/kg to 150 mg/kg) via examination of bioconcentration factor (BCF), translocation factor (TF), and total removal (TR). Exposure to Cd levels of up to 150 mg/kg in the trials did not affect the biomass of the plants compared to the control. Impatiens glandulifera accumulated cadmium at a rate of 276 to 1562 mg/kgin stems, with BCFs, TFs, and TRs of 64.6 to 236.4, 0.2 to 1.2, and 3.6 to 29.2 mg Cd, respectively. In vitro germination revealed unprecedented germination ability, demonstrating the remarkable hypertolerance of I. glandulifera, with no significant difference in the germination of seedlings exposed to 1000 mg/kg Cd compared to the control. This study also examined the localization of Cd in plant tissues via a histochemical assay using dithizone. The results presented herein suggest that I. glandulifera can act as a hyperaccumulator of Cd for phytoremediation.