title: Ammonium-dependent respiratory increase is dependent on the cytochrome pathway in Arabidopsis thaliana shoots.
abstract: Oxygen uptake rates are increased when concentrated ammonium instead of nitrate is used as sole N source. Several explanations for this increased respiration have been suggested, but the underlying mechanisms are still unclear. To investigate possible factors responsible for this respiratory increase, we measured the O₂ uptake rate, activity and transcript level of respiratory components, and concentration of adenylates using Arabidopsis thaliana shoots grown in media containing various N sources. The O₂ uptake rate was correlated with concentrations of ammonium and ATP in shoots, but not related to the ammonium assimilation. The capacity of the ATP-coupling cytochrome pathway (CP) and its related genes were up-regulated when concentrated ammonium was sole N source, whereas the ATP-uncoupling alternative oxidase did not influence the extent of the respiratory increase. Our results suggest that the ammonium-dependent increase of the O₂ uptake rate can be explained by the up-regulation of the CP, which may be related to the ATP consumption by the plasma-membrane H+ -ATPase.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. takushi@biol.s.u-tokyo.ac.jp
authors.forename: Takushi
authors.initials: T
authors.lastname: Hachiya
authors.forename: Chihiro K
authors.initials: CK
authors.lastname: Watanabe
authors.forename: Carolina
authors.initials: C
authors.lastname: Boom
authors.forename: Danny
authors.initials: D
authors.lastname: Tholen
authors.forename: Kentaro
authors.initials: K
authors.lastname: Takahara
authors.forename: Maki
authors.initials: M
authors.lastname: Kawai-Yamada
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Uchimiya
authors.forename: Yukifumi
authors.initials: Y
authors.lastname: Uesono
authors.forename: Ichiro
authors.initials: I
authors.lastname: Terashima
authors.forename: Ko
authors.initials: K
authors.lastname: Noguchi
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D019069:Cell Respiration; D003574:Cytochrome c Group / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D024101:Mitochondrial Proteins; D009154:Mutation; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D010101:Oxygen Consumption; D010940:Plant Proteins; D000644:Quaternary Ammonium Compounds / Q000378:metabolism*; D018749:RNA, Plant / Q000235:genetics; D000099188:Alternative Oxidase
chemical_list: D000255:Adenosine Triphosphate; D003574:Cytochrome c Group; D024101:Mitochondrial Proteins; D009566:Nitrates; D009584:Nitrogen; D010088:Oxidoreductases; D010940:Plant Proteins; D000644:Quaternary Ammonium Compounds; D018749:RNA, Plant; D000099188:Alternative Oxidase