INFLUENCE OF CO2 CONCENTRATION AND LIGHT- INTENSITY ON PHOSPHOENOLPYRUVATE CARBOXYLASE AND MALATE-DEHYDROGENASE OF IN-VITRO COFFEE PLANTLETS

Coffee plantlets were grown on media containing 3 % sucrose under ligh t intensities of 100 and 260 mu mol m(-2) s(-1) (PFD) in vessels which were either closed or permitted a continuous air flow of different CO 2 concentrations. Both amount and activity of phosphoenolpyruvate carb oxylase (PEPCase) und malate dehydrogenase (MDH) of in vitro grown lea ves were measured. Two different isoforms of PEPCase (100 and 110 kD) were found. The 200 kD isoform was present in higher amounts compared to the 110 kD isoform. Increased CO2 concentrations during growth indu ced a rise of the specific enzyme activity. Maximum activity was measu red after treatment with 1000 mu l l(-1) CO2 and 100 mu mol m(-2) s(-1 ) PFD.