title: Analysis of the sodium chloride-dependent respiratory kinetics of wheat mitochondria reveals differential effects on phosphorylating and non-phosphorylating electron transport pathways.
abstract: A number of previous studies have documented the gross response of mitochondrial respiration to salinity treatment, but it is unclear how NaCl directly affects the kinetics of plant phosphorylating and non-phosphorylating electron transport pathways. This study investigates the direct effects of NaCl upon different respiratory pathways in wheat, by measuring rates of isolated mitochondrial oxygen consumption across different substrate oxidation pathways in saline media. We also profile the abundance of respiratory proteins by using targeted selected reaction monitoring (SRM) mass spectrometry of mitochondria isolated from control and salt-treated wheat plants. We show that all pathways of electron transport were inhibited by NaCl concentrations above 400 mM; however electron transfer chains showed divergent responses to NaCl concentrations between 0 and 200 mM. Stimulation of oxygen consumption was measured in response to NaCl in scenarios where exogenous NADH was provided as substrate and electron flow was coupled to the generation of a proton gradient across the inner membrane. Protein abundance measurements show that several enzymes with activities less affected by NaCl are induced by salinity, whereas enzymes with activities inhibited by NaCl are depleted. These data deepen our understanding of how plant respiration responds to NaCl, offering new mechanistic explanations for the divergent salinity responses of whole-plant respiratory rate in the literature.
authors.affiliation: ARC Centre of Excellence in Plant Energy Biology, M316, The University of Western Australia, Crawley, WA, 6009, Australia.|Botanical Institute and Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Cologne, 50674, Germany.
authors.forename: R P
authors.initials: RP
authors.lastname: Jacoby
authors.affiliation: ARC Centre of Excellence in Plant Energy Biology, M316, The University of Western Australia, Crawley, WA, 6009, Australia.|School of Chemistry and Biochemistry, M316, The University of Western Australia, Crawley, WA, 6009, Australia.
authors.forename: M H
authors.initials: MH
authors.lastname: Che-Othman
authors.affiliation: ARC Centre of Excellence in Plant Energy Biology, M316, The University of Western Australia, Crawley, WA, 6009, Australia.
authors.forename: A H
authors.initials: AH
authors.lastname: Millar
authors.affiliation: ARC Centre of Excellence in Plant Energy Biology, M316, The University of Western Australia, Crawley, WA, 6009, Australia.|School of Chemistry and Biochemistry, M316, The University of Western Australia, Crawley, WA, 6009, Australia.
authors.forename: N L
authors.initials: NL
authors.lastname: Taylor
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D019069:Cell Respiration / Q000187:drug effects; D004579:Electron Transport / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D007700:Kinetics; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D010101:Oxygen Consumption / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D012965:Sodium Chloride / Q000494:pharmacology*; D014908:Triticum / Q000187:drug effects / Q000378:metabolism*
chemical_list: D012965:Sodium Chloride; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide
keywords: SRM mass spectrometry; Triticum spp; alternative oxidase; mitochondrial electron transfer; oxidative phosphorylation; respiration