title: Limited accumulation of copper in heavy metal adapted mosses.
abstract: Copper is an essential micronutrient but has toxic effects at high concentrations. Bryophytes are remarkably tolerant to elevated levels of copper but we wondered if this tolerance might be species dependent. Therefore, in three moss species, Physcomitrella patens, Mielichhoferia elongata and Pohlia drummondii, the accumulation of copper was compared with semiquantitative SEM-EDX analyses after six weeks of cultivation on copper containing media. We investigated the role of the copper-linked anion and applied copper as CuCl2, CuSO4 and CuEDTA, respectively. Line scans along the growth axis of moss gametophores allowed for a detailed analysis of copper detection from the base towards the tip. Mosses originating from metal-containing habitats (i.e. M. elongata and P. drummondii) revealed a lower accumulation of copper when compared to the non-adapted P. patens. CuEDTA had a shielding effect in all three species and copper levels differed greatly from CuCl2 or CuSO4. The detection of reactive oxygen species (ROS), H2O2 and O2(-), was further used to indicate stress levels in the gametophore stems. ROS staining was increased along the whole stem and the tip in the non-adapted species P. patens whereas the tolerant species M. elongata and P. drummondii generally showed less staining located mainly at the base of the stem. We discuss the relation between metal accumulation and ROS production using indicator dyes in the three moss species. As moss gametophores are very delicate structures, ROS staining provide an excellent alternative to spectrophotometric analyses to estimate stress levels.
authors.affiliation: Cell Imaging and Ultrastructure Research, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, A-1090, Vienna, Austria. Electronic address: sebastian.antreich@univie.ac.at.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Antreich
authors.affiliation: Cell Imaging and Ultrastructure Research, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, A-1090, Vienna, Austria; Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, EX4 4QD, Exeter, United Kingdom. Electronic address: s.sassmann@exeter.ac.uk.
authors.forename: Stefan
authors.initials: S
authors.lastname: Sassmann
authors.affiliation: Cell Imaging and Ultrastructure Research, Faculty of Life Sciences, University of Vienna, Althanstrasse 14, A-1090, Vienna, Austria. Electronic address: ingeborg.lang@univie.ac.at.
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Lang
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects* / Q000502:physiology; D044002:Bryophyta / Q000378:metabolism*; D002712:Chlorides / Q000494:pharmacology*; D003300:Copper / Q000378:metabolism*; D019327:Copper Sulfate / Q000494:pharmacology*
chemical_list: D002712:Chlorides; D003300:Copper; D019327:Copper Sulfate
keywords: 3,3′-diaminobenzidine (DAB); Bryophytes; Copper tolerance; Element analysis; Nitroblue tetrazoliumchloride (NBT); Reactive oxygen species (ROS); Scanning electron microscopy