Tolerance mechanism and phytoremediation potential of Pistia stratiotes to zinc and cadmium co-contamination
2022
Li, Yan | Xin, Jianpan | Ge, Wenjia | Tian, Runan
Pistia stratiotes can not only effectively remediate eutrophic water, but also displays strong absorption and bioaccumulation abilities for heavy metals. However, it has not been well-understood how the plant resists the combined stress of heavy metals. In these experiments, the morphophysiological traits, the ascorbate-glutathione (AsA-GSH) cycle, the glyoxalase system, and the contents of zinc (Zn) and cadmium (Cd) were investigated under Zn and Cd co-pollution. The AsA-GSH cycle and glyoxalase system could coordinately alleviate the oxidative and carbonyl stress, which was identified as an important tolerance mechanism. With Zn₅₀Cd₁, Zn₅₀Cd₁₀, Zn₁₀₀Cd₁, and Zn₁₀₀Cd₁₀ treatments for 18 days, 90.75–93.69% of Zn and 88.13–96.96% Cd accumulated in the roots. Treatments with Zn₅₀Cd₅₀, and Zn₁₀₀Cd₅₀ for 18 days resulted in a decrease of stress tolerance and chlorophyll content in leaves, an increase in plasma membrane permeability, a massive accumulation of methylglyoxal (MG), and visible toxic symptoms. Additionally, the bioaccumulation factor (BCF) for roots and shoots and the translocation factor (TF) were >1, and the content of Cd in shoots was no <100 mg·kg⁻¹. This indicated P. stratiotes was a Cd hyperaccumulator and have great potential for the phytoremediation of heavy metal contaminated water. Novelty statement Pistia stratiotes, a cadmium hyperaccumulator, has great application potential for the phytoremediation of zinc and cadmium co-polluted water.
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