Selenate increased plant growth and arsenic uptake in As-hyperaccumulator Pteris vittata via glutathione-enhanced arsenic reduction and translocation

The beneficial effects of selenium on As uptake and plant growth in As-hyperaccumulator Pteris vittata are known, but the associated mechanisms remain unclear. Here, we investigated the effects of selenate on arsenic accumulation by P. vittata under two arsenate levels. P. vittata plants were exposed to 13 (As-13) or 133 mu M (As-133) arsenate and 5 mu M selenate in 0.2-strength Hoagland solution. After 14 d of growth, plant biomass, Se and As content, As speciation, and malondialdehyde (MDA), glutathione reductase (GR), glutathione peroxidase (GPX), and glutathione (GSH and GSSG) levels were determined. The results show that selenate promoted P. vittata growth and increased As concentrations in the roots and fronds by 256% from 97 to 346 mg kg(-1) and 142% from 213 to 514 mg kg(-1) under As-13 treatment, and by 166% from 500 to 1332 mg kg(-1) and 534% from 777 to 4928 mg kg(-1) under As-133 treatment. In addition, selenate increased the glutathione content in P. vittata roots and fronds by 75-86% under As-13 treatment and 44-45% under As-133 treatment. Selenate also increased the GPX activity by 161-173%, and GR activity by 72-79% in P. vittata under As-13 and As-133 treatments. The HPLC-ICP-MS analysis indicated that selenate increased both AsIII and AsV levels in P. vittata, with AsIII/AsV ratio being lower in the roots and higher in the fronds, i.e., more AsIII was being translocated to the fronds. Taken together, our results suggest that, via GPX-GR mediated enhancement of GSH-GSSG cycle, selenate effectively increases plant growth and As uptake in P. vittata by improving AsV reduction in the roots and AsIII translocation from the roots to the fronds.

Automated summary

The study found that selenate promotes plant growth and increases arsenic concentrations in both roots and fronds of Pteris vittata. Additionally, selenate enhances glutathione levels and the activity of GPX and GR in the plant, suggesting an effective mechanism for improving arsenic uptake.