title: Influence of temperature on measurements of the CO2 compensation point: differences between the Laisk and O2-exchange methods.
abstract: 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.
authors: School of Biological Sciences, Molecular Plant Sciences, Washington State University, PO Box 644236, Pullman, WA 99164-4236, USA.
authors: Berkley J
authors: BJ
authors: Walker
authors: Asaph B
authors: AB
authors: Cousins
mesh_terms: D017360:Arabidopsis / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism*; D019069:Cell Respiration / Q000502:physiology; D008954:Models, Biological; D010100:Oxygen / Q000378:metabolism*; D010788:Photosynthesis / Q000502:physiology; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism*; D013696:Temperature
chemical_list: D002245:Carbon Dioxide; D012273:Ribulose-Bisphosphate Carboxylase; D010100:Oxygen
references: Biochem J. 1974 Feb;138(2):217-24
references: 4362741
references: New Phytol. 1990 Nov;116(3):505-529
references: 33874095
references: Plant Physiol. 1998 Feb 1;116(2):539-46
references: 9490757
references: Plant Physiol. 1996 Mar;110(3):903-912
references: 12226229
references: J Exp Bot. 2008;59(7):1581-95
references: 18436544
references: Physiol Plant. 2004 Feb;120(2):179-186
references: 15032851
references: Photosynth Res. 2011 Sep;108(2-3):91-100
references: 21567290
references: Plant Cell Environ. 2011 May;34(5):837-46
references: 21332508
references: Plant Cell Environ. 2011 Apr;34(4):580-91
references: 21251018
references: Plant Physiol. 1980 Aug;66(2):302-7
references: 16661426
references: Planta. 1980 Jun;149(1):78-90
references: 24306196
references: Biochim Biophys Acta. 1973 Oct 19;325(1):182-8
references: 4149156
references: Planta. 1985 Aug;165(3):397-406
references: 24241146
references: Annu Rev Plant Physiol Plant Mol Biol. 1999 Jun;50:601-639
references: 15012221
references: Planta. 1978 Jan;144(1):31-7
references: 24408641
references: Proc Natl Acad Sci U S A. 2008 Jan 15;105(2):797-802
references: 18184808
references: Planta. 1981 Dec;153(4):376-87
references: 24276943
references: Planta. 1977 Jan;133(3):261-6
references: 24425260
references: Philos Trans R Soc Lond B Biol Sci. 2000 Oct 29;355(1402):1433-46
references: 11127997
references: Photosynth Res. 2009 Nov-Dec;102(2-3):511-22
references: 19653116
references: Plant Physiol. 1987 Jan;83(1):69-74
references: 16665218
references: J Exp Bot. 2000 Feb;51 Spec No:357-68
references: 10938843
references: Plant Physiol. 2002 Dec;130(4):1992-8
references: 12481082
references: Funct Plant Biol. 2009 Nov;36(11):845-856
references: 32688695
references: J Exp Bot. 2008;59(7):1475-87
references: 17975206
references: Plant Physiol. 1998 Feb 1;116(2):627-35
references: 9490763
references: Plant Physiol. 1992 Jan;98(1):294-302
references: 16668627
references: Arch Biochem Biophys. 1985 Mar;237(2):300-13
references: 3919644
references: Plant Physiol. 1998 Jan;116(1):259-69
references: 9449845
references: Plant J. 2007 May;50(3):381-90
references: 17376163
references: Plant Physiol. 2008 Oct;148(2):786-95
references: 18685043
references: Biochem J. 1974 Jan;138(1):77-85
references: 4840839
references: Curr Opin Plant Biol. 2002 Jun;5(3):193-8
references: 11960735
references: Planta. 1984 Jun;161(4):308-13
references: 24253719
references: Plant Physiol. 1994 May;105(1):167-172
references: 12232196
references: Biochim Biophys Acta. 2006 Dec;1763(12):1496-510
references: 17046077