Contribution of the cytochrome and alternative pathways to growth respiration and maintenance respiration in Arabidopsis thaliana

Authors

  • Igor D. Florez-Sarasa,

    1. Grup de Recerca en Biología de Plantes en Condicions Mediterrànies, Departament de Biología, Universitat de les Illes Balears, Ctra. Valldemossa Km. 7.5, 07122 Palma de Mallorca, Spain
    2. Unitat de Fisiologia Vegetal, Facultat de Biología, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
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  • Tjeerd J. Bouma,

    1. Netherlands Institute of Ecology, 4400AC Yerseke, The Netherlands
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  • Hipólito Medrano,

    1. Grup de Recerca en Biología de Plantes en Condicions Mediterrànies, Departament de Biología, Universitat de les Illes Balears, Ctra. Valldemossa Km. 7.5, 07122 Palma de Mallorca, Spain
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  • Joaquin Azcon-Bieto,

    1. Unitat de Fisiologia Vegetal, Facultat de Biología, Universitat de Barcelona, Diagonal 645, 08028 Barcelona, Spain
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  • Miquel Ribas-Carbo

    Corresponding author
    1. Grup de Recerca en Biología de Plantes en Condicions Mediterrànies, Departament de Biología, Universitat de les Illes Balears, Ctra. Valldemossa Km. 7.5, 07122 Palma de Mallorca, Spain
      *e-mail: mribas@uib.es
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*e-mail: mribas@uib.es

Abstract

The activities of the cytochrome and alternative respiratory pathways were measured during the growth cycle in Arabidopsis thaliana using a newly developed Isotope Ratio Mass Spectrometer (IRMS) dual-inlet system that allows very precise measurements of oxygen-isotope fractionation under low oxygen consumption rates. Under optimum growth conditions, the relative growth rate was highly dependent on the activity of the cytochrome pathway. The activity of the alternative pathway was almost constant irrespective of the growth rate and appeared mostly involved in the maintenance respiration component, although the alternative pathway also played a role under optimum growth conditions. This is the first time that the contribution of the two respiratory pathways to the two main respiratory components (growth and maintenance) has been analyzed with the use of the oxygen-isotope fractionation technique. The respiration efficiency of the specific costs for growth and maintenance (adenosine triphosphate/O2 ratio) was determined by a modified regression model. The ability to measure oxygen-isotope fractionation during respiration in A. thaliana opens the door to a wider set of studies that are discussed.

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