title: The response of the foliar antioxidant system and stable isotopes (δ(13)C and δ(15)N) of white willow to low-level air pollution.
abstract: In this study we aimed to determine and elucidate the effect of ambient air pollution on the foliar antioxidant system and stable carbon and nitrogen isotopes of white willow (Salix alba L.). We grew white willow in uniform potting soil in the near vicinity of sixteen air quality monitoring stations in Belgium where nitrogen dioxide (NO2), ozone, sulfur dioxide and particulate matter concentrations were continuously measured. The trees were exposed to ambient air during six months (April-September 2011), and, thereafter, the degree of lipid peroxidation and foliar content of antioxidant molecules (ascorbate, glutathione, polyphenols, flavonoids), antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, peroxidase) and foliar stable carbon (δ(13)C) and nitrogen (δ(15)N) isotopes were measured. We found that lipid peroxidation was caused by air pollution stress, arising from high ambient NO2 concentrations, as shown by an increased amount of malondialdehyde. The antioxidant system was activated by increasing the amount of polyphenols at monitoring stations with a high atmospheric NO2 and low O3 concentration, while no increase of key enzymes (e.g., ascorbate, glutathione) was observed. The δ(13)C also decreased with increasing NO2 concentrations and decreasing O3 concentrations, probably reflecting a decreased net photosynthesis and/or a concomitant decrease of (13)CO2 in the atmosphere. Shade also influenced foliar δ(13)C and the content of leaf ascorbate and glutathione.
authors.affiliation: Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. Electronic address: tatiana.wuytack@ua.ac.be.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Wuytack
authors.affiliation: Laboratory for Molecular Plant Physiology and Biotechnology, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. Electronic address: hamadagh_2005@yahoo.com.
authors.forename: Hamada
authors.initials: H
authors.lastname: AbdElgawad
authors.affiliation: Isotope Bioscience Laboratory (ISOFYS), Department of Applied Analytical and Physical Chemistry, Ghent University, Coupure Links 653, B-9000 Gent, Belgium; Forest & Nature Lab, Department of Forest and Water Management, Ghent University, Geraardsbergsesteenweg 267, B-9090 Gontrode, Melle, Belgium. Electronic address: jeroen_staelens@yahoo.com.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Staelens
authors.affiliation: Laboratory for Molecular Plant Physiology and Biotechnology, Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. Electronic address: han.asard@ua.ac.be.
authors.forename: Han
authors.initials: H
authors.lastname: Asard
authors.affiliation: Isotope Bioscience Laboratory (ISOFYS), Department of Applied Analytical and Physical Chemistry, Ghent University, Coupure Links 653, B-9000 Gent, Belgium. Electronic address: pascal.boeckx@ugent.be.
authors.forename: Pascal
authors.initials: P
authors.lastname: Boeckx
authors.affiliation: Forest & Nature Lab, Department of Forest and Water Management, Ghent University, Geraardsbergsesteenweg 267, B-9090 Gontrode, Melle, Belgium. Electronic address: kris.verheyen@ugent.be.
authors.forename: Kris
authors.initials: K
authors.lastname: Verheyen
authors.affiliation: Department of Bioscience Engineering, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium. Electronic address: roeland.samson@ua.ac.be.
authors.forename: Roeland
authors.initials: R
authors.lastname: Samson
mesh_terms: D000397:Air Pollution / Q000009:adverse effects*; D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000378:metabolism; D002247:Carbon Isotopes / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000187:drug effects; D009585:Nitrogen Dioxide / Q000378:metabolism; D009587:Nitrogen Isotopes / Q000378:metabolism*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D032108:Salix / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D001205:Ascorbic Acid; D009585:Nitrogen Dioxide
keywords: Active biomonitoring; Ambient air pollution; Antioxidant enzymes; Ascorbate; Glutathione; Lipid peroxidation; Polyphenols; δ(13)C; δ(15)N