title: Copper speciation and isotopic fractionation in plants: uptake and translocation mechanisms.
abstract: The fractionation of stable copper (Cu) isotopes during uptake into plant roots and translocation to shoots can provide information on Cu acquisition mechanisms. Isotope fractionation ((65) Cu/(63) Cu) and intact tissue speciation techniques (X-ray absorption spectroscopy, XAS) were used to examine the uptake, translocation and speciation of Cu in strategy I (tomato-Solanum lycopersicum) and strategy II (oat-Avena sativa) plant species. Plants were grown in controlled solution cultures, under varied iron (Fe) conditions, to test whether the stimulation of Fe-acquiring mechanisms can affect Cu uptake in plants. Isotopically light Cu was preferentially incorporated into tomatoes (Δ(65) Cu(whole plant-solution ) = c. -1‰), whereas oats showed minimal isotopic fractionation, with no effect of Fe supply in either species. The heavier isotope was preferentially translocated to shoots in tomato, whereas oat plants showed no significant fractionation during translocation. The majority of Cu in the roots and leaves of both species existed as sulfur-coordinated Cu(I) species resembling glutathione/cysteine-rich proteins. The presence of isotopically light Cu in tomatoes is attributed to a reductive uptake mechanism, and the isotopic shifts within various tissues are attributed to redox cycling during translocation. The lack of isotopic discrimination in oat plants suggests that Cu uptake and translocation are not redox selective.
authors.affiliation: Soil Sciences, University of Adelaide, Adelaide, SA, 5064, Australia.
authors.forename: Brooke M
authors.initials: BM
authors.lastname: Ryan
authors.affiliation: CSIRO Land and Water, Contaminant Chemistry and Ecotoxicology Program, Waite Campus, Adelaide, SA, 5064, Australia.
authors.forename: Jason K
authors.initials: JK
authors.lastname: Kirby
authors.affiliation: Soil Sciences, University of Adelaide, Adelaide, SA, 5064, Australia.
authors.forename: Fien
authors.initials: F
authors.lastname: Degryse
authors.affiliation: School of Chemistry and Physics, University of Adelaide, Adelaide, SA, 5000, Australia.
authors.forename: Hugh
authors.initials: H
authors.lastname: Harris
authors.affiliation: Soil Sciences, University of Adelaide, Adelaide, SA, 5064, Australia.|CSIRO Land and Water, Contaminant Chemistry and Ecotoxicology Program, Waite Campus, Adelaide, SA, 5064, Australia.
authors.forename: Mike J
authors.initials: MJ
authors.lastname: McLaughlin
authors.affiliation: CSIRO Land and Water, Contaminant Chemistry and Ecotoxicology Program, Waite Campus, Adelaide, SA, 5064, Australia.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Scheiderich
mesh_terms: D018554:Avena / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D018533:Biomass; D005591:Chemical Fractionation / Q000379:methods*; D003300:Copper / Q000378:metabolism*; D005583:Fourier Analysis; D007501:Iron / Q000494:pharmacology; D007554:Isotopes; D018551:Solanum lycopersicum / Q000378:metabolism*; D008954:Models, Biological; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D056928:X-Ray Absorption Spectroscopy
chemical_list: D007554:Isotopes; D003300:Copper; D007501:Iron