Arsenic transformation in the growth media and biomass of hyperaccumulator Pteris vittata L.

This study determined the role of plant and microbes in arsenite (AsIII) oxidation in the growth media and the location of AsIII oxidation and arsenate (AsV) reduction in Pteris vittata tissues. P. vittata grew in 0.10-0.27mM AsV or AsIII solution under aerated or sterile condition for 1h to 14d. Arsenic speciation was conducted in the growth media, biomass (roots, rhizomes, rachis, pinnae, and fronds), and sap (rhizomes and fronds). Arsenite was rapidly oxidized in the growth media by microbes (18-67% AsV after 1d) and was then further oxidized in the roots of P. vittata (35% AsV in the roots growing in AsIII media). While limited reduction occurred in the roots (7-8% as AsIII), AsV reduction mostly occurred in the rhizomes (68-71% as AsIII) and pinnae (>90% as AsIII) of P. vittata. Regardless AsIII or AsV was supplied, AsV dominated in the roots while AsIII dominated in the rhizomes and fronds. AsIII translocation from the roots to the fronds was more rapid than AsV. This study shed new insights into arsenic transformation in the growth media and P. vittata biomass and raise new question into the tissue distribution of arsenic reducing and oxidizing enzymes in P. vittata.