Influence of temperature on measurements of the CO2 compensation point : differences between the Laisk and O2-exchange methods
The CO2 compensation point in the absence of day respiration (Γ*) is a key parameter for modelling leaf CO2 exchange. Γ* links the kinetics of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) with the stoichiometry of CO2 released per Rubisco oxygenation from photorespiration (α), two essen...
| Veröffentlicht in: | Journal of experimental botany. - 1985. - 64(2013), 7 vom: 29. Apr., Seite 1893-905 |
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| Format: | Online-Aufsatz |
| Sprache: | English |
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2013
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| Zugriff auf das übergeordnete Werk: | Journal of experimental botany |
| Schlagworte: | Journal Article Research Support, Non-U.S. Gov't Carbon Dioxide 142M471B3J Ribulose-Bisphosphate Carboxylase EC 4.1.1.39 Oxygen S88TT14065 |
| Zusammenfassung: | The CO2 compensation point in the absence of day respiration (Γ*) is a key parameter for modelling leaf CO2 exchange. Γ* links the kinetics of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) with the stoichiometry of CO2 released per Rubisco oxygenation from photorespiration (α), two essential components of biochemical models of photosynthesis. There are two main gas-exchange methods for measuring Γ*: (i) the Laisk method, which requires estimates of mesophyll conductance to CO2 (g m) and (ii) measurements of O2 isotope exchange, which assume constant values of α and a fixed stoichiometry between O2 uptake and Rubisco oxygenation. In this study, the temperature response of Γ* measured using the Laisk and O2-exchange methods was compared under ambient (25 °C) and elevated (35 °C) temperatures to determine whether both methods yielded similar results. Previously published temperature responses of Γ* estimated with the Laisk and O2-exchange methods in Nicotiana tabacum demonstrated that the Laisk-derived model of Γ* was more sensitive to temperature compared with the O2-exchange model. Measurements in Arabidopsis thaliana indicated that the Laisk and O2-exchange methods produced similar Γ* at 25 °C; however, Γ* values from O2 exchange were lower at 35 °C compared with the Laisk method. Compared with a photorespiratory mutant (pmdh1pmdh2hpr) with increased α, wild-type (WT) plants had lower Laisk values of Γ* at 25 °C but were not significantly different at 35 °C. These differences between Laisk and O2 exchange values of Γ* at 35 °C could be explained by temperature sensitivity of α in WT and/or errors in the assumptions of O2 exchange. The differences between Γ* measured using the Laisk and O2-exchange method with temperature demonstrate that assumptions used to measure Γ*, and possibly the species-specific validity of these assumptions, need to be considered when modelling the temperature response of photosynthesis |
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| Beschreibung: | Date Completed 30.05.2014 Date Revised 22.03.2024 published: Print Citation Status MEDLINE |
| ISSN: | 1460-2431 |
| DOI: | 10.1093/jxb/ert058 |