title: Overcoming ammonium toxicity.
abstract: Ammonia (ammonium ion under physiological conditions) is one of the key nitrogen sources in cellular amino acid biosynthesis. It is continuously produced in living organisms by a number of biochemical processes, but its accumulation in cells leads to tissue damage. Current knowledge suggests that a few enzymes and transporters are responsible for maintaining the delicate balance of ammonium fluxes in plant tissues. In this study we analyze the data in the scientific literature and the publicly available information on the dozens of biochemical reactions in which endogenous ammonium is produced or consumed, the enzymes that catalyze them, and the enzyme and transporter mutants listed in plant metabolic and genetic databases (Plant Metabolic Network, TAIR, and Genevestigator). Our compiled data show a surprisingly high number of little-studied reactions that might influence cellular ammonium concentrations. The role of ammonium in apoptosis, its relation to oxidative stress, and alterations in ammonium metabolism induced by environmental stress need to be explored in order to develop methods to manage ammonium toxicity.
authors.affiliation: Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Otto 15, 1022 Budapest, Hungary.
authors.forename: András
authors.initials: A
authors.lastname: Bittsánszky
authors.affiliation: Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Otto 15, 1022 Budapest, Hungary.
authors.forename: Katalin
authors.initials: K
authors.lastname: Pilinszky
authors.affiliation: Department of Genetics and Plant Breeding, Szent István University, Páter K. 1, 2103 Gödöllő, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Gyulai
authors.affiliation: Plant Protection Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Otto 15, 1022 Budapest, Hungary. Electronic address: komives.tamas@agrar.mta.hu.
authors.forename: Tamas
authors.initials: T
authors.lastname: Komives
mesh_terms: D064751:Ammonium Compounds / Q000378:metabolism / Q000633:toxicity*; D009584:Nitrogen / Q000378:metabolism; D010944:Plants / Q000187:drug effects / Q000378:metabolism
chemical_list: D064751:Ammonium Compounds; D009584:Nitrogen
keywords: Ammonia; Ammonium; Cellular responses; Phytotoxicity; Selective ammonia uptake, transport and detoxification