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Title: IMPROVED TEMPERATURE RESPONSE FUNCTIONS FOR MODELS OF RUBISCO-LIMITED PHOTOSYNTHESIS

Author
item BERNACCHI, C - PLANT BIOLOGY UOFI URBANA
item SINGSAAS, E - PLANT BIOLOGY UOFI URBANA
item PIMMENTEL, C - CROP SCIENCES UOFI URBANA
item PORTIS JR, ARCHIE
item LONG, STEVEN - CROP SCEINCES UOFI URBANA

Submitted to: Plant Cell and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2000
Publication Date: 2/1/2001
Citation: Bernacchi, C.J., Singsaas, E.L., Pimmentel, C., Portis Jr, A.R., Long, S.P. 2001. Improved temperature response functions for models of rubisco-limited photosynthesis. Plant Cell and Environment. 24:253-259

Interpretive Summary: Predicting the environmental responses of leaf photosynthesis is central to many models attempting to assess the impacts of global climate change. Photosynthetic rates are usually limited by the activity of the enzyme, Rubisco. In this study, transgenic tobacco plants containing only 10 percent normal levels of Rubisco were used to measure Rubisco-limited photosynthesis at a wide range of temperatures in order to derive improved temperature functions of Rubisco kinetic properties. The results represent an improved ability to model leaf photosynthesis at various temperatures, which is necessary for predicting global carbon uptake in response to global climate change.

Technical Abstract: Predicting the environmental responses of leaf photosynthesis is central to many models of changes in the future global carbon cycle and terrestrial biosphere. The steady-state biochemical model of C3 photosynthesis of Farquhar et al. (1980;Planta 149,78-79) provides a basis for these larger scale predictions, but a weakness in the application of the model as currently parameterized is the inability to predict carbon assimilation at the range of temperatures over which significant photosynthesis occurs in the natural environment. In this study, transgenic tobacco containing only 10 percent normal levels of Rubisco were used to measure Rubisco-limited photosynthesis over a large range of CO2 concentrations. From the responses of the rate of CO2 assimilation at a wide range of temperatures, and CO2 and O2 concentrations, the temperature functions of Rubisco kinetic properties were estimated in vivo. Those differed substantially from previously published functions. These new functions were then used to predict photosynthesis in lemon and found to faithfully mimic the observed pattern of temperature response. There was also a close correspondence with published C3 photosynthesis temperature responses, The results represent an improved ability to model leaf photosynthesis over the wide range of temperatures necessary for predicting carbon uptake by terrestrial C3 systems.