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

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 As and 1.9, 3.8, or 7.6 mg L F, or 3) 1 mg L F and 3.75 mg L or 7.5 mg L As for 7 d in hydroponics. P. ensiformis accumulated 14.7-32.6 mg kg As at 3.75 mg L AsV, and 99-145 mg kg F at 1 mg L F. Our study revealed that AsV and F increased each other's uptake when co-present. At 1.9 mg L, F increased frond As uptake from 14.7 to 40.3 mg kg, while 7.5 mg L As increased frond F uptake from 99 to 371 mg kg. 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 HO 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.