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Title: IN VIVO TEMPERATURE RESPONSE FUNCTIONS FOR LEAF STEADY-STATE PHOTOSYNTHESIS MODELS

Author
item BERNACCHI, CARL - PLANT BIOLOGY UOFI URBANA
item SINBSAAS, E - MICHIGAN BIOLOGIVCAL STA
item PIMENTEL, C - UNIV FEDERAL RURAL BRAZIL
item PORTIS JR, ARCHIE
item LONG, S - PLANT BIOLOGY UOFI URBANA

Submitted to: Photosynthesis International Congress Symposium Proceedings and Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/25/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Predicting environmental responses of leaf photosynthesis is central for modeling changes in the future global carbon cycle and terrestrial biosphere. A biochemical model of C3 photosynthesis of Farquhar et al provides a basis for larger scale predications; but weakness as currently parameterized is the inability to predict accurately carbon assimilation over an ecologically significant range of temperatures. Previous parameters were based on in vitro measurements made over a limited temperature range and require several assumptions of in vivo conditions. Both anti-rbcS, for estimating Rubisco kinetics over a larger range of Ci, and wild-type tobacco, to estimate RuBP regeneration kinetics, were used in this study.Temperature functions of kinetic properties were estimated in vivo from the rate of CO2 assimilation over a wide range of temperatures, CO2 and O2 concentrations. The results differed substantially from previously published functions. These new functions were used to predict photosynthesis in lemon and found to faithfully mimic the observed pattern of temperature response. Gas-exchange measurements coupled with fluorescence were made to determine temperature response of mesophyll conductance for estimating Rubisco kinetics based on CO2 concentrations at chloroplast level. Results represented an improved ability to model leaf photosynthesis over a wide range of temperatures (10-40degreeC) necessary for predicting carbon uptake by terrestrial C3 systems.