title: Impaired Cyclic Electron Flow around Photosystem I Disturbs High-Light Respiratory Metabolism.
abstract: The cyclic electron flow around photosystem I (CEF-PSI) increases ATP/NADPH production in the chloroplast, acting as an energy balance mechanism. Higher export of reducing power from the chloroplast in CEF-PSI mutants has been correlated with higher mitochondrial alternative oxidase (AOX) capacity and protein amount under high-light (HL) conditions. However, in vivo measurements of AOX activity are still required to confirm the exact role of AOX in dissipating the excess of reductant power from the chloroplast. Here, CEF-PSI single and double mutants were exposed to short-term HL conditions in Arabidopsis (Arabidopsis thaliana). Chlorophyll fluorescence, in vivo activities of the cytochrome oxidase (νcyt) and AOX (νalt) pathways, levels of mitochondrial proteins, metabolite profiles, and pyridine nucleotide levels were determined under normal growth and HL conditions. νaltwas not increased in CEF-PSI mutants, while AOX capacity was positively correlated with photoinhibition, probably due to a reactive oxygen species-induced increase of AOX protein. The severe metabolic impairment observed in CEF-PSI mutants, as indicated by the increase in photoinhibition and changes in the levels of stress-related metabolites, can explain their lack of νaltinduction. By contrast, νcytwas positively correlated with photosynthetic performance. Correlations with metabolite changes suggest that νcytis coordinated with sugar metabolism and stress-related amino acid synthesis. Furthermore, changes in glycine-serine and NADH-NAD+ratios were highly correlated to νcytTaken together, our results suggest that νcytcan act as a sink for the excess of electrons from the chloroplast, probably via photorespiratory glycine oxidation, thus improving photosynthetic performance when νaltis not induced under severe HL stress.
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, 14476 Potsdam-Golm, Germany (I.F.-S., A.R.F.).|School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan (K.N.).|Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Vicosa, Minas Gerais 36570-000, Brazil (W.L.A.).|Área de Ecología, Departamento Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, 41013 Seville, Spain (A.G.-N.); and.|Grup de Recerca en Biologia de les Plantes en Condicions Mediterranies, Departament de Biologia, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain (J.F., M.R.-C.).
authors.forename: Igor
authors.identifier: 0000-0002-1862-7931
authors.initials: I
authors.lastname: Florez-Sarasa
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, 14476 Potsdam-Golm, Germany (I.F.-S., A.R.F.).|School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan (K.N.).|Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Vicosa, Minas Gerais 36570-000, Brazil (W.L.A.).|Área de Ecología, Departamento Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, 41013 Seville, Spain (A.G.-N.); and.|Grup de Recerca en Biologia de les Plantes en Condicions Mediterranies, Departament de Biologia, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain (J.F., M.R.-C.).
authors.forename: Ko
authors.initials: K
authors.lastname: Noguchi
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, 14476 Potsdam-Golm, Germany (I.F.-S., A.R.F.).|School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan (K.N.).|Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Vicosa, Minas Gerais 36570-000, Brazil (W.L.A.).|Área de Ecología, Departamento Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, 41013 Seville, Spain (A.G.-N.); and.|Grup de Recerca en Biologia de les Plantes en Condicions Mediterranies, Departament de Biologia, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain (J.F., M.R.-C.).
authors.forename: Wagner L
authors.initials: WL
authors.lastname: Araújo
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, 14476 Potsdam-Golm, Germany (I.F.-S., A.R.F.).|School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan (K.N.).|Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Vicosa, Minas Gerais 36570-000, Brazil (W.L.A.).|Área de Ecología, Departamento Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, 41013 Seville, Spain (A.G.-N.); and.|Grup de Recerca en Biologia de les Plantes en Condicions Mediterranies, Departament de Biologia, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain (J.F., M.R.-C.).
authors.forename: Ana
authors.identifier: 0000-0002-6124-3415
authors.initials: A
authors.lastname: Garcia-Nogales
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, 14476 Potsdam-Golm, Germany (I.F.-S., A.R.F.).|School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan (K.N.).|Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Vicosa, Minas Gerais 36570-000, Brazil (W.L.A.).|Área de Ecología, Departamento Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, 41013 Seville, Spain (A.G.-N.); and.|Grup de Recerca en Biologia de les Plantes en Condicions Mediterranies, Departament de Biologia, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain (J.F., M.R.-C.).
authors.forename: Alisdair R
authors.initials: AR
authors.lastname: Fernie
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, 14476 Potsdam-Golm, Germany (I.F.-S., A.R.F.).|School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan (K.N.).|Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Vicosa, Minas Gerais 36570-000, Brazil (W.L.A.).|Área de Ecología, Departamento Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, 41013 Seville, Spain (A.G.-N.); and.|Grup de Recerca en Biologia de les Plantes en Condicions Mediterranies, Departament de Biologia, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain (J.F., M.R.-C.).
authors.forename: Jaume
authors.initials: J
authors.lastname: Flexas
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, 14476 Potsdam-Golm, Germany (I.F.-S., A.R.F.); mribas@uib.cat.|School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan (K.N.); mribas@uib.cat.|Max-Planck Partner Group at the Departamento de Biologia Vegetal, Universidade Federal de Viçosa, Vicosa, Minas Gerais 36570-000, Brazil (W.L.A.); mribas@uib.cat.|Área de Ecología, Departamento Sistemas Físicos, Químicos y Naturales, Universidad Pablo de Olavide, 41013 Seville, Spain (A.G.-N.); and mribas@uib.cat.|Grup de Recerca en Biologia de les Plantes en Condicions Mediterranies, Departament de Biologia, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain (J.F., M.R.-C.) mribas@uib.cat.
authors.forename: Miquel
authors.identifier: 0000-0002-7337-2089
authors.initials: M
authors.lastname: Ribas-Carbo
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects*; D019069:Cell Respiration / Q000528:radiation effects; D002734:Chlorophyll / Q000378:metabolism; D004579:Electron Transport / Q000528:radiation effects; D003576:Electron Transport Complex IV / Q000378:metabolism; D005453:Fluorescence; D008401:Gas Chromatography-Mass Spectrometry; D008027:Light; D055442:Metabolome / Q000528:radiation effects; D055432:Metabolomics; D008928:Mitochondria / Q000378:metabolism / Q000528:radiation effects; D024101:Mitochondrial Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D009711:Nucleotides / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D010788:Photosynthesis / Q000528:radiation effects; D045331:Photosystem I Protein Complex / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D000099188:Alternative Oxidase
chemical_list: D002734:Chlorophyll; D003576:Electron Transport Complex IV; D024101:Mitochondrial Proteins; D009711:Nucleotides; D010088:Oxidoreductases; D045331:Photosystem I Protein Complex; D010940:Plant Proteins; D000099188:Alternative Oxidase