title: Uncertainty in measurements of the photorespiratory CO2compensation point and its impact on models of leaf photosynthesis.
abstract: Rates of carbon dioxide assimilation through photosynthesis are readily modeled using the Farquhar, von Caemmerer, and Berry (FvCB) model based on the biochemistry of the initial Rubisco-catalyzed reaction of net C3photosynthesis. As models of CO2assimilation rate are used more broadly for simulating photosynthesis among species and across scales, it is increasingly important that their temperature dependencies are accurately parameterized. A vital component of the FvCB model, the photorespiratory CO2compensation point (Γ*), combines the biochemistry of Rubisco with the stoichiometry of photorespiratory release of CO2. This report details a comparison of the temperature response of Γ*measured using different techniques in three important model and crop species (Nicotiana tabacum, Triticum aestivum, and Glycine max). We determined that the different Γ*determination methods produce different temperature responses in the same species that are large enough to impact higher-scale leaf models of CO2assimilation rate. These differences are largest in N. tabacum and could be the result of temperature-dependent increases in the amount of CO2lost from photorespiration per Rubisco oxygenation reaction.
authors.affiliation: Global Change and Photosynthesis Research Unit, United State Department of Agriculture/Agricultural Research Services, University of Illinois, 1206 W Gregory Dr., Urbana, IL, 61801, USA.|Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, 61801, USA.|Biochemistry of Plants, Heinrich-Heine University, Düsseldorf, Germany.
authors.forename: Berkley J
authors.identifier: http://orcid.org/0000-0001-5932-6468
authors.initials: BJ
authors.lastname: Walker
authors.affiliation: Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK.|Plant Biology and Crop Science, Rothamsted Research, Harpenden, AL5 2JQ, UK.
authors.forename: Douglas J
authors.identifier: http://orcid.org/0000-0003-1217-537X
authors.initials: DJ
authors.lastname: Orr
authors.affiliation: Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK.|Plant Biology and Crop Science, Rothamsted Research, Harpenden, AL5 2JQ, UK.
authors.forename: Elizabete
authors.identifier: http://orcid.org/0000-0001-6059-9359
authors.initials: E
authors.lastname: Carmo-Silva
authors.affiliation: Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK.|Plant Biology and Crop Science, Rothamsted Research, Harpenden, AL5 2JQ, UK.
authors.forename: Martin A J
authors.initials: MAJ
authors.lastname: Parry
authors.affiliation: Global Change and Photosynthesis Research Unit, United State Department of Agriculture/Agricultural Research Services, University of Illinois, 1206 W Gregory Dr., Urbana, IL, 61801, USA.|Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, 61801, USA.|Department of Plant Biology, University of Illinois, Urbana, IL, 61801, USA.
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Bernacchi
authors.affiliation: Global Change and Photosynthesis Research Unit, United State Department of Agriculture/Agricultural Research Services, University of Illinois, 1206 W Gregory Dr., Urbana, IL, 61801, USA. d-ort@illinois.edu.|Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, IL, 61801, USA. d-ort@illinois.edu.|Department of Plant Biology, University of Illinois, Urbana, IL, 61801, USA. d-ort@illinois.edu.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Ort
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism*; D019069:Cell Respiration / Q000502:physiology; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000378:metabolism; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D013696:Temperature
chemical_list: D002245:Carbon Dioxide; D012273:Ribulose-Bisphosphate Carboxylase
keywords: Modeling photosynthesis; Photorespiration; Rubisco; Temperature response