Arsenic alters uptake and distribution of sulphur in Pteris vittata

Low‐molecular‐weight thiol (LMWT) synthesis has been reported to be directly induced by arsenic (As) in Pteris vittata, an As hyperaccumulator. Sulphur (S) is a critical component of LMWTs. Here, the effect of As treatment on the uptake and distribution of S in P. vittata was investigated. In P. vittata grown under low S conditions, the presence of As in the growth medium enhanced the uptake of SO42−, which was used for LMWT synthesis in fronds. In contrast, As application did not affect SO42− uptake in Nephrolepis exaltata, an As non‐hyperaccumulator. Moreover, the isotope microscope system revealed that S absorbed with As accumulated locally in a vacuole‐like organelle in epidermal cells, whereas S absorbed alone was distributed uniformly. These results suggest that S is involved in As transport and/or accumulation in P. vittata. X‐ray absorption near‐edge structure analysis revealed that the major As species in the fronds and roots of P. vittata were inorganic As(III) and As(V), respectively, and that As–LMWT complexes occurred as a minor species. Consequently, in case of As accumulation in P. vittata, S possibly acts as a temporary ligand for As in the form of LMWTs in intercellular and/or intracellular transport (e.g. vacuolar sequestration). In Pteris vittata, an arsenic (As) hyperaccumulator, As application enhanced the uptake of SO42−, which was used for low‐molecular‐weight thiol synthesis in fronds. Moreover, sulphur (S) absorbed with As accumulated locally in a vacuole‐like organelle in epidermal cells of fronds, whereas S absorbed alone was distributed uniformly. Thus, this study demonstrates that As has a dramatic impact on the metabolisms and accumulation of S in P. vittata.