Biochemical model of C3photosynthesis applied to wheat at different temperatures.
We examined the effects of leaf temperature on the estimation of maximal Rubisco capacity (Vcmax) from gas exchange measurements of wheat leaves using a C3photosynthesis model. Cultivars of spring wheat (Triticum aestivum (L)) and triticale (X Triticosecale Wittmack) were grown in a greenhouse or in the field and measured at a range of temperatures under controlled conditions in a growth cabinet (2 and 21% O2) or in the field using natural diurnal variation in temperature, respectively. Published Rubisco kinetic constants for tobacco did not describe the observed CO2response curves well as temperature varied. By assuming values for the Rubisco Michaelis-Menten constants for CO2(Kc) and O2(Ko) at 25 °C derived from tobacco and the activation energies of Vcmaxfrom wheat and respiration in the light, Rd, from tobacco, we derived activation energies for Kcand Ko(93.7 and 33.6 kJ mol-1, respectively) that considerably improved the fit of the model to observed data. We confirmed that temperature dependence of dark respiration for wheat was well described by the activation energy for Rdfrom tobacco. The new parameters improved the estimation of Vcmaxunder field conditions, where temperatures increased through the day.
CSIRO Agriculture and Food, PO Box 1700, Canberra, Australian Capital Territory, 2601, Australia.
Viridiana
V
Silva-Pérez
Plant Science Division, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, 2601, Australia.
Robert T
RT
Furbank
CSIRO Agriculture and Food, PO Box 1700, Canberra, Australian Capital Territory, 2601, Australia.
Anthony G
AG
Condon
Plant Science Division, Research School of Biology, The Australian National University, Canberra, Australian Capital Territory, 2601, Australia.
John R
http://orcid.org/0000-0003-1379-3532
JR
Evans
D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D019069:Cell Respiration / Q000528:radiation effects; D002736:Chloroplasts / Q000378:metabolism / Q000528:radiation effects; D004777:Environment; D007700:Kinetics; D008027:Light; D008954:Models, Biological; D010788:Photosynthesis / Q000528:radiation effects; D018515:Plant Leaves / Q000502:physiology / Q000528:radiation effects; D015203:Reproducibility of Results; D012273:Ribulose-Bisphosphate Carboxylase / Q000378:metabolism; D013696:Temperature; D014908:Triticum / Q000502:physiology* / Q000528:radiation effects
D002245:Carbon Dioxide; D002244:Carbon; D012273:Ribulose-Bisphosphate Carboxylase
CO2 compensation point; CO2 response curves; Michaelis-Menten kinetic constants; Rubisco; Triticum aestivum; activation energy; respiration