Inorganic Phosphate Absorption and its Effect on the Adenosine 5′-triphosphate Level in Suspension Cultured Cells of Catharanthus roseus

Abstract

Summary Inorganic phosphate (Pi) was absorbed rapidly by Catharanthus roseus cells previously cultured in a Pi-free Murashige-Skoog medium for 67 hrs. The absorption of Pi increased for at least 6 hrs after Pi-addition and more than 85 % of the absorbed Pi was present as free Pi and the rest was converted into organic phosphates within the cells. The ATP level in the cells was increased by Pi and a maximum level was observed when the initial medium Pi was 10–20 mM. During 3 hrs of incubation with 10 mM Pi, the ATP level was 4-5 times that of the Pi-starved control cells. Since only a slight decrease in ADP and AMP level was observed with the Pi-treatment, the marked increase in ATP level with Pi seems to depend upon the net synthesis of adenine nucleotides.