Impacts of sulfur regulation in vivo on arsenic accumulation and tolerance of hyperaccumulator Pteris vittata

The impacts of the regulation of sulfur (S) metabolism in vivo on arsenic (As) and S species and on As accumulation by Pteris vittata L were investigated using a synchrotron-based X-ray-absorption fine structure method. The S assimilation inhibitor L-buthionine-sulfoximine (BSO) markedly inhibited As reduction, doubling arsenate (As(V)) content in P. vittata rhizoids. The resulting As transport blockage in rhizoids, decreased As movement to aboveground tissues by 47%. The significant impact of BSO demonstrated the vital role of sulfhydryl groups (-SH) as reductants in As(V) reduction and confirmed the importance of As(V) reduction in As accumulation in this fern. The S metabolism accelerant O-acetyl-L-serine resulted in the appearance of large amounts of As-SH in rhizoids and had no obvious impact on As accumulation, but with As stress conditions, effectively increased plant biomass, possibly through chelation of excess As with -SH. Thus, -SH appeared able to act as both a reductant and a chelator of As in P. vittata, and the ratio of -SH to As may have been a factor that determined the specific role of -SH in P. vittata under these conditions. (C) 2012 Elsevier B.V. All rights reserved.