title: Arsenic uptake and speciation in the rootless duckweed Wolffia globosa.
abstract: Duckweeds are a common macrophyte in paddy and aquatic environments. Here, we investigated arsenic (As) accumulation, speciation and tolerance of the rootless duckweed Wolffia globosa and its potential for As phytofiltration. When grown with 1 microm arsenate, W. globosa accumulated two to 10 times more As than four other duckweed or Azolla species tested. W. globosa was able to accumulate > 1000 mg As kg(-1) in frond dry weight (DW), and tolerate up to 400 mg As kg(-1) DW. At the low concentration range, uptake rate was similar for arsenate and arsenite, but at the high concentration range, arsenite was taken up at a faster rate. Arsenite was the predominant As species (c. 90% of the total extractable As) in both arsenate- and arsenite-exposed duckweed. W. globosa was more resistant to external arsenate than arsenite, but showed a similar degree of tolerance internally. W. globosa decreased arsenate in solution rapidly, but also effluxed arsenite. Wolffia globosa is a strong As accumulator and an interesting model plant to study As uptake and metabolism because of the lack of a root-to-frond translocation barrier.
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Soil Science Department, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
authors.forename: Fang-Jie
authors.initials: FJ
authors.lastname: Zhao
authors.affiliation: Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361003, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Huang
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Paul N
authors.initials: PN
authors.lastname: Williams
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Guo-Xin
authors.initials: GX
authors.lastname: Sun
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.|Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361003, China.
authors.forename: Yong-Guan
authors.initials: YG
authors.lastname: Zhu
mesh_terms: D000222:Adaptation, Physiological; D001149:Arsenates / Q000737:chemistry / Q000145:classification / Q000378:metabolism*; D001151:Arsenic / Q000378:metabolism*; D018053:Arsenites / Q000737:chemistry / Q000145:classification / Q000378:metabolism*; D019684:Magnoliopsida / Q000254:growth & development / Q000378:metabolism*
chemical_list: D001149:Arsenates; D018053:Arsenites; C015001:arsenite; D001151:Arsenic; C025657:arsenic acid