Effects of Zn on plant tolerance and non-protein thiol accumulation in Zn hyperaccumulator Arabis paniculata Franch

This experiment investigated the Zn accumulation and tolerance, and responses of non-protein thiols in Zn hyperaccumulator Arabis paniculata under different Zn stress (0, 100, 250, 500, 1000 and 2000 μM Zn). No obvious phytotoxicity or biomass reduction was observed in the plants during a 3-w of growth. Compared to the control, addition of 100–500 μM Zn increased plant biomass by 18–38%. The high Zn concentrations in the roots (9025–12,892 mg kg−1) and the shoots (777–6030 mg kg−1) did not impair the membrane stability or increase the lipid peroxidation except for the roots treated with 2000 μM Zn. Substantial amounts of Zn accumulated in the plant were water-soluble, with 58–73% in the shoots and 30–53% in the roots. Low Zn translocation from the shoots to the roots was observed in all treatments. This phenomenon was consistent with the XRD analysis, which showed the presence of ZnO and ZnS in the ashed-roots. No phytochelatin was detected in the shoots and only PC4 was eluted in the roots, suggesting their limited role in Zn tolerance in A. paniculata. While glutathione did not correspond to Zn loading in plants, cysteine had significant positive correlation with Zn concentration in plants. Our data suggested that A. paniculata exhibited high Zn tolerance and cysteine may be involved in its Zn tolerance.

Research highlights▶ No obvious phytotoxicity or biomass reduction in Zn hyperaccumulator Arabis paniculata was observed after growing 3 weeks under different Zn stress (0–2000 μM Zn). ▶ Substantial amounts of Zn accumulated in A. paniculata were water-soluble, with 58–73% in the shoots and 30–53% in the roots. ▶ Low Zn translocation from the shoots to the roots was observed in all treatments. ▶ A. paniculata exhibited high Zn tolerance and cysteine may be involved in its Zn tolerance.