title: Xylem- and phloem-based transport of CuO nanoparticles in maize (Zea mays L.).
abstract: This work reports on the toxicity of CuO nanoparticles (NPs) to maize (Zea mays L.) and their transport and redistribution in the plant. CuO NPs (100 mg L(-1)) had no effect on germination, but inhibited the growth of maize seedlings; in comparison the dissolved Cu(2+) ions and CuO bulk particles had no obvious effect on maize growth. CuO NPs were present in xylem sap as examined by transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS), showing that CuO NPs were transported from roots to shoots via xylem. Split-root experiments and high-resolution TEM observation further showed that CuO NPs could translocate from shoots back to roots via phloem. During this translocation, CuO NPs could be reduced from Cu (II) to Cu (I). To our knowledge, this is the first report of root-shoot-root redistribution of CuO NPs within maize. The current study provides direct evidence for the bioaccumulation and biotransformation of CuO NPs (20-40 nm) in maize, which has significant implications on the potential risk of NPs and food safety.
authors.affiliation: College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, People's Republic of China.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Wang
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Xie
authors.forename: Jian
authors.initials: J
authors.lastname: Zhao
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Liu
authors.forename: Wenqiang
authors.initials: W
authors.lastname: Feng
authors.forename: Jason C
authors.initials: JC
authors.lastname: White
authors.forename: Baoshan
authors.initials: B
authors.lastname: Xing
mesh_terms: D001692:Biological Transport; D001711:Biotransformation; D003300:Copper / Q000378:metabolism* / Q000633:toxicity; D018525:Germination / Q000187:drug effects; D053758:Nanoparticles / Q000633:toxicity; D052585:Phloem / Q000378:metabolism*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D052584:Xylem / Q000378:metabolism*; D003313:Zea mays / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*
chemical_list: D003300:Copper; C030973:cupric oxide