title: Copper ultrastructural localization, subcellular distribution, and phytotoxicity in Hydrilla verticillata (L.f.) Royle.
abstract: Laboratory experiments were conducted to investigate copper (Cu) subcellular distribution and toxicity in Hydrilla verticillata. Fronds were subjected to different concentrations (15, 75, and 150 μM) of Cu for 7 days. Cu grains were found in cell walls, plasmodesmata, and within the nuclei and chloroplasts using the autometallographic technique. Subcellular fractionation of Cu-containing tissues indicated that in leaves subjected to high Cu concentrations, 59-65 % of the element was located in the cell wall fraction, followed by cell organelles (21-30 %) and the soluble fraction (10-14 %). The levels of K, P, Zn, and Mg declined under all Cu concentrations, but Ca, Mn, and Fe contents reached their peak at 15 μM Cu and decreased thereafter. F v/F m, F 0, and F m fell significantly in line with the decrease in pigment content. Cu exposure also caused significant damage to the chloroplasts, mitochondria, and nuclei, including disintegration of the chloroplasts and vacuolization of the mitochondria and nuclei, all of which suggested that Cu hastened plant senescence. The Cu maximum permissible concentration for H. verticillata was 10 μM, which was less than the existing general water quality standard. This suggested that H. verticillata could be used to assess Cu phytotoxicity.
authors.affiliation: Institute of Plant Cell and Molecular Biology, College of Life Sciences, Nanjing Normal University, Nanjing, 210023, People's Republic of China, xuqinsong@163.com.
authors.forename: Qinsong
authors.initials: Q
authors.lastname: Xu
authors.forename: Han
authors.initials: H
authors.lastname: Qiu
authors.forename: Weiyue
authors.initials: W
authors.lastname: Chu
authors.forename: Yongyang
authors.initials: Y
authors.lastname: Fu
authors.forename: Sanjuan
authors.initials: S
authors.lastname: Cai
authors.forename: Haili
authors.initials: H
authors.lastname: Min
authors.forename: Sha
authors.initials: S
authors.lastname: Sha
mesh_terms: D002736:Chloroplasts / Q000378:metabolism; D003300:Copper / Q000378:metabolism* / Q000633:toxicity; D031321:Hydrocharitaceae / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D018515:Plant Leaves / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000378:metabolism* / Q000633:toxicity
chemical_list: D014874:Water Pollutants, Chemical; D003300:Copper