A CO2 Concentrating System in Leaves of Higher C3-Plants Predicted by a Model Based on RuBP Carboxylase/Oxygenase Kinetics and 14CO2/12CO2 Exchange

Mâchler, F., Lehnherr, B., Schnyder, H. and Nosberger, J. 1985. A C02 concentrating system in leaves of higher C3-plants predicted by a model based on RuBP carboxylase/oxygenase kinetics and 14C02/12C02 exchange.—J. exp. Bot. 36: 1542-1550. A model is presented which compares the ratio of the two activities of the enzyme ribulose bisphosphate carboxylase/oxygenase as determined in vitro with the ratio of photosynthesis to photorespiration in leaves as determined from differential 14C02/' 2CO, uptake or from C02 compensation concentration. Discrepancies between measurements made in vitro and in vivo are attributed to the effect of a C02 concentrating system in the leaf cells. Interference from dark respiration is discussed. A C02 concentrating system is postulated which is efficient mainly at low temperature and low C02 concentration.