Author's personal copy Sulfate and glutathione enhanced arsenic accumulation by arsenic hyperaccumulator Pteris vittata L. Shuhe Wei a , Lena Q. Ma a, b, * , Uttam Saha b , Shiny Mathews b , Sabarinath Sundaram c , Bala Rathinasabapathi c , Qixing Zhou a, * a Key Laboratory of Terrestrial Ecological Processes, Institute of Applied Ecology, Shenyang 110116, PR China b Soil and Water Science Department, University of Florida, Gainesville, FL 32611-0290, USA c Horticultural Sciences Department, University of Florida, Gainesville, FL 32611-0690, USA Sulfate and glutathione increased arsenic uptake and translocation in Pteris vittata. article info Article history: Received 20 August 2009 Received in revised form 8 December 2009 Accepted 12 December 2009 Keywords: Sulfur Arsenic Hyperaccumulator GSH abstract This experiment examined the effects of sulfate (S) and reduced glutathione (GSH) on arsenic uptake by arsenic hyperaccumulator Pteris vittata after exposing to arsenate (0, 15 or 30 mg As L 1 ) with sulfate (6.4, 12.8 or 25.6 mg S L 1 ) or GSH (0, 0.4 or 0.8 mM) for 2-wk. Total arsenic, S and GSH concentrations in plant biomass and arsenic speciation in the growth media and plant biomass were determined. While both S (18–85%) and GSH (77–89%) significantly increased arsenic uptake in P. vittata, GSH also increased arsenic translocation by 61–85% at 0.4 mM (p < 0.05). Sulfate and GSH did not impact plant biomass or arsenic speciation in the media and biomass. The S-induced arsenic accumulation by P. vittata was partially attributed to increased plant GSH (21–31%), an important non-enzymatic antioxidant coun- tering oxidative stress. This experiment demonstrated that S and GSH can effectively enhance arsenic uptake and translocation by P. vittata. Published by Elsevier Ltd. 1. Introduction Arsenic-contaminated soils and waters are of great concern worldwide due to arsenic’s toxicity as a carcinogen (Tripathi et al., 2007). Phytoextraction has the potential to clean up those contaminated sites. It uses hyperaccumulating plants to concen- trate arsenic in the aboveground biomass, which can be harvested and removed. Identification of arsenic hyperaccumulators, such as fern species in the Pteris genus (Ma et al., 2001; Srivastava et al., 2006), makes phytoextraction of arsenic-contaminated sites a viable technology. As the first-known arsenic hyperaccumulator, Pteris vittata L. (Chinese brake fern) has received much attention due to its exceptional ability to tolerate and hyperaccumulate arsenic. When cultivated in an arsenic-contaminated soil containing 1500 mg kg 1 arsenic, it accumulated 22,630 mg kg 1 arsenic in its fronds (Ma et al., 2001). In a hydroponic system containing 150 mg L 1 arsenic, the plant accumulated up to 27,000 mg kg 1 arsenic (Wang et al., 2002). As an efficient arsenic hyperaccumulator, P. vittata must possess mechanisms to efficiently detoxify the accumulated arsenic in the biomass. Several mechanisms have been proposed including chelation, compartmentalization, biotransformation and cellular repair (Gonzaga et al., 2006). The roles of non-enzymatic antioxi- dant glutathione (GSH) in arsenic accumulation by P. vittata remain unclear. With the increase of arsenic levels in the growth media, GSH concentrations in the fronds of P. vittata significantly increased (Cao et al., 2004). For example, GSH concentration in the mature fronds of P. vittata growing in soil with 200 mg As kg 1 for 12 weeks was 2.8 times more than that with 20 mg As kg 1 . Similar trends were observed by Srivastava et al. (2005) and Singh et al. (2006) in hydroponic systems. However, this was not observed by Zhao et al. (2003). GSH concentrations in the fronds of P. vittata remain unchanged when P. vittata was exposed to 0.5 mM arsenic for 5 d or to 50 mM arsenic for 1–7 d in a hydroponic system (Zhao et al., 2003). The shorter exposure time and/or the lower arsenic concentrations may account for the different results. One of the arsenic detoxification mechanisms in P. vittata is via reduction of arsenate (AsV) to arsenite (AsIII) in the fronds, which is then possibly transported to vacuoles for storage (Lombi et al., 2002). This has been confirmed in yeast where vacuolar * Corresponding authors at: Key Laboratory of Terrestrial Ecological Processes, Institute of Applied Ecology, Shenyang 110116, PR China. Tel.: þ86 352 392 9063; fax: þ86 352 392 3902. E-mail address: lqma@ufl.edu (L.Q. Ma). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol 0269-7491/$ – see front matter Published by Elsevier Ltd. doi:10.1016/j.envpol.2009.12.024 Environmental Pollution 158 (2010) 1530–1535