title: Long-term ammonium nutrition of Arabidopsis increases the extrachloroplastic NAD(P)H/NAD(P)(+) ratio and mitochondrial reactive oxygen species level in leaves but does not impair photosynthetic capacity.
abstract: Ammonium nutrition has been suggested to be associated with alterations in the oxidation-reduction state of leaf cells. Herein, we show that ammonium nutrition in Arabidopsis thaliana increases leaf NAD(P)H/NAD(P)(+) ratio, reactive oxygen species content and accumulation of biomolecules oxidized by free radicals. We used the method of rapid fractionation of protoplasts to analyse which cellular compartments were over-reduced under ammonium supply and revealed that observed changes in NAD(P)H/NAD(P)(+) ratio involved only the extrachloroplastic fraction. We also showed that ammonium nutrition changes mitochondrial electron transport chain activity, increasing mitochondrial reactive oxygen species production. Our results indicate that the functional impairment associated with ammonium nutrition is mainly associated with redox reactions outside the chloroplast.
authors.affiliation: Faculty of Biology, Institute of Experimental Plant Biology and Biotechnology, University of Warsaw, I. Miecznikowa 1, 02-096, Warsaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Podgórska
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Gieczewska
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Łukawska-Kuźma
authors.forename: Allan G
authors.initials: AG
authors.lastname: Rasmusson
authors.forename: Per
authors.initials: P
authors.lastname: Gardeström
authors.forename: Bożena
authors.initials: B
authors.lastname: Szal
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000378:metabolism; D064751:Ammonium Compounds / Q000494:pharmacology*; D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D019069:Cell Respiration / Q000187:drug effects; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism*; D004734:Energy Metabolism / Q000187:drug effects; D005453:Fluorescence; D006861:Hydrogen Peroxide / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009249:NADP / Q000378:metabolism*; D009566:Nitrates / Q000494:pharmacology; D010084:Oxidation-Reduction / Q000187:drug effects; D010788:Photosynthesis / Q000187:drug effects*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D064751:Ammonium Compounds; D009566:Nitrates; D017382:Reactive Oxygen Species; D002734:Chlorophyll; D009249:NADP; D006861:Hydrogen Peroxide; D000594:Amino Acid Oxidoreductases; D000077194:Chlorophyll A
keywords: ROS metabolism; chloroplasts; mitochondria; photosynthesis; redox homeostasis; reductive stress