Characteristics of arsenic accumulation by Pteris and non-Pteris ferns

This research was conducted to understand the mechanisms of arsenic hyperaccumulation in Pteris vittata by comparing the characteristics of arsenic accumulation in Pteris and non-Pteris ferns. Seven Pteris (P.vittata, P. Cretica Rowerii, P. Cretica Parkerii, P. Cretica Albo-lineata, P. Quadriavrita, P. Ensiformis and P. Dentata) and six non-Pteris (Arachnoides simplicor, Didymochlaena truncatula, Dryopteris atrata, Dryopteris erythrosora, Cyrtomium falcatum, and Adiantum hispidulum) ferns were exposed to 0, 1 and 10 mgL(-1) arsenic as sodium arsenate for 14-d in hydroponic systems. As a group, the Pteris ferns were more efficient in arsenic accumulation than the non-Pteris ferns, with P. vittata being the most efficient followed by P. cretica. When exposed to 10 mg L-1 As, arsenic concentrations in the fronds and roots of P. vittata were 1748 and 503 mg kg(-1). Though not all Pteris ferns were efficient in accumulating arsenic, none of the non-Pteris ferns was an efficient As accumulator (the highest concentration being 452 mg kg(-1)). The fact that frond arsenic concentrations in the control were highly correlated with those exposed to As (r(2) = 0.76-0.87) may suggest that they may be used as a preliminary tool to screen potential arsenic hyperaccumulators. Our research confirms that the ability of P. vittata to translocate arsenic from the roots to the fronds (73-77% As in the fronds), reduce arsenate to arsenite in the fronds (> 50% AsIII in the fronds), and maintain high concentrations of phosphate in the roots (48-53% in the roots) all contributed to its arsenic tolerance and hyperaccumulation.