Steps towards a mechanistic understanding of respiratory temperature responses

Authors


Author for correspondence:
Jörg Kruse
Tel: +49 (0) 761 203 8300
Fax: +49 (0) 761 203 8302
Email: joerg.kruse@ctp.uni-freiburg.de

Abstract

Contents

 Summary659
I.Introduction660
II.Representation of the instantaneous temperature response of respiration661
III.Temperature responses of mitochondrial oxygen reduction662
IV.The temperature response of CO2 respiration671
V.Conclusion673
 Acknowledgements673
 References674

Summary

Temperature crucially affects the speed of metabolic processes in poikilotherm organisms, including plants. The instantaneous temperature responses of O2-reduction and CO2-release can be approximated by Arrhenius kinetics, even though respiratory gas exchange of plants is the net effect of many constituent biochemical processes. Nonetheless, the classical Arrhenius equation must be modified to account for a dynamic response to measurement temperatures. We show that this dynamic response is readily explained by combining Arrhenius and Michaelis–Menten kinetics, as part of a fresh appraisal of metabolic interpretations of instantaneous temperature responses. In combination with recent experimental findings, we argue that control of mitochondrial electron flow is shared among cytochrome oxidase and alternative oxidase under in vivo conditions, and is continuously coordinated. In this way, upstream carbohydrate metabolism and downstream electron transport appear to be optimized according to the demand of ATP, TCA-cycle intermediates and anabolic reducing power under differing metabolic states. We provide a link to the ‘Growth and Maintenance Paradigm’ of respiration and argue that respiratory temperature responses can be used as a tool to probe metabolic states of plant tissue, such that we can learn more about the mechanisms that govern longer-term acclimatization responses of plant metabolism.

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