Arsenate and fluoride enhanced each other's uptake in As-sensitive plant Pteris ensiformis

•Impact of As and F on uptake and tolerance by Pteris ensiformis was investigated.•F increased As uptake and As increased F uptake by P. ensiformis.•AsV was the predominant As, but F enhanced AsIII levels in the rhizome and fronds.•F alleviated As stress by minimizing TBARS and H2O2 levels in P. ensiformis.•P. ensiformis roots showed signs of membrane leakage under As exposure.

We investigated the effects of arsenate (AsV) and fluoride (F) on each other's uptake in an As-sensitive plant Pteris ensiformis. Plants were exposed to 1) 0.1 × Hoagland solution control, 2) 3.75 mg L−1 As and 1.9, 3.8, or 7.6 mg L−1 F, or 3) 1 mg L−1 F and 3.75 mg L−1 or 7.5 mg L−1 As for 7 d in hydroponics. P. ensiformis accumulated 14.7-32.6 mg kg−1 As at 3.75 mg L−1 AsV, and 99-145 mg kg−1 F at 1 mg L−1 F. Our study revealed that AsV and F increased each other's uptake when co-present. At 1.9 mg L−1, F increased frond As uptake from 14.7 to 40.3 mg kg−1, while 7.5 mg L−1 As increased frond F uptake from 99 to 371 mg kg−1. Although, AsV was the predominant As species in all tissues, F enhanced AsIII levels in the rhizomes and fronds, while the reverse was observed in the roots. Increasing As concentrations also enhanced TBARS and H2O2 in tissues, indicating oxidative stress. However, F alleviated As stress by lowering their levels in the fronds. Frond and root membrane leakage were also evident due to As or F exposure. The results may facilitate better understanding of the mechanisms underlying the co-uptake of As and F in plants. However, the mechanisms of how they enhance each other's uptake in P. ensiformis need further investigation.

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