title: Phytochelatins play a key role in arsenic accumulation and tolerance in the aquatic macrophyte Wolffia globosa.
abstract: The rootless duckweed Wolffia globosa can accumulate and tolerate relatively large amounts of arsenic (As); however, the underlying mechanisms were unknown. W. globosa was exposed to different concentrations of arsenate with or without l-buthionine sulphoximine (BSO), a specific inhibitor of γ-glutamylcysteine synthetase. Free thiol compounds and As(III)-thiol complexes were identified and quantified using HPLC - high resolution ICP-MS - accurate mass ESI-MS. Without BSO, 74% of the As accumulated in the duckweed was complexed with phytochelatins (PCs), with As(III)-PC(4) and As(III)-PC(3) being the main species. BSO was taken up by the duckweed and partly deaminated. The BSO treatment completely suppressed the synthesis of PCs and the formation of As(III)-PC complexes, and also inhibited the reduction of arsenate to arsenite. BSO markedly decreased both As accumulation and As tolerance in W. globosa. The results demonstrate an important role of PCs in detoxifying As and enabling As accumulation in W. globosa.
authors.affiliation: State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.forename: M Kalle
authors.initials: MK
authors.lastname: Uroic
authors.forename: Wan-Ying
authors.initials: WY
authors.lastname: Xie
authors.forename: Yong-Guan
authors.initials: YG
authors.lastname: Zhu
authors.forename: Bao-Dong
authors.initials: BD
authors.lastname: Chen
authors.forename: Steve P
authors.initials: SP
authors.lastname: McGrath
authors.forename: Jörg
authors.initials: J
authors.lastname: Feldmann
authors.forename: Fang-Jie
authors.initials: FJ
authors.lastname: Zhao
mesh_terms: D000222:Adaptation, Physiological; D029064:Araceae / Q000502:physiology*; D001151:Arsenic / Q000032:analysis / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019328:Buthionine Sulfoximine / Q000378:metabolism; D054811:Phytochelatins / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D014874:Water Pollutants, Chemical; D019328:Buthionine Sulfoximine; D054811:Phytochelatins; D001151:Arsenic