Three parameters comprehensively describe the temperature response of respiratory oxygen reduction

Authors

  • JÖRG KRUSE,

    1. School of Forest and Ecosystem Science, University of Melbourne, Water St, Creswick, Vic. 3363, Australia and
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  • MARK A. ADAMS

    Corresponding author
    1. School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
      M. A. Adams. Fax: +61 2 9385 2120; e-mail: Mark.Adams@unsw.edu.au
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M. A. Adams. Fax: +61 2 9385 2120; e-mail: Mark.Adams@unsw.edu.au

ABSTRACT

Using an exponential model that relies on Arrhenius kinetics, we explored Type I, Type II and dynamic (e.g. declining Q10 with increasing temperature) responses of respiration to temperature. Our Arrhenius model provides three parameters: RREF (the base of the exponential model, nmol g−1 s−1), E0 (the overall activation energy of oxygen reduction that dominates its temperature sensitivity, kJ mol−1) and δ (that describes dynamic responses of E0 to measurement temperature, 103 K2). Two parameters, E0 and δ, are tightly linked. Increases in overall activation energy at a reference temperature were inversely related to changes in δ. At an E0 of ca. 45 kJ mol−1, δ approached zero, and respiratory temperature response was strictly Arrhenius-like. Physiologically, these observations suggest that as contributions of AOX to combined oxygen reduction increase, E0(REF) decreases because of different temperature sensitivities for Vmax, and δ increases because of different temperature sensitivities for K1/2 of AOX and COX. The balance between COX and AOX activity helps regulate plant metabolism by adjusting the demand for ATP to that for reducing power and carbon skeleton intermediates. Our approach enables determination of respiratory capacity in vivo and opens a path to development of process-based models of plant respiration.

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