Transport of arsenite by the arsenic hyperaccumulating brake fern Pteris Vittata is inhibited by monovalent silver

The capacity of silver (Ag⁺) to inhibit the transport of arsenite by the arsenic (As) hyperaccumulating fern Pteris vittata was investigated. The hydroponic growth medium was supplemented with 200 M arsenite and 1, 10, or 100 M Ag⁺, with roots and pinnae harvested intermittently following treatment. Treatment with Ag⁺ significantly reduced transpiration and prevented the hyperaccumulation of As. A study of competitive uptake between arsenite and its analog antimonite showed that arsenite significantly reduced the concentration of antimonite in P. vittata, but antimonite had no effect on As accumulation. The results collectively suggest that uptake of arsenite by Pteris vittata is mediated by membrane transporters sensitive to Ag⁺ inhibition that may also mediate antimonite transport, such as members of the major intrinsic protein family.