Choline kinase activities in choline-sensitive and choline-resistant tobacco cells or calluses grown on high choline concentrations. Effects on phosphatidylcholine synthesis

Abstract

The choline-resistant tobacco tissues routinely cultivated in the presence of 10 mM choline chloride exhibited the same phospholipid composition but a lower choline kinase activity per mg of protein than the choline-sensitive tissues cultivated in the absence of choline. Increasing choline concentrations had no effect on the choline kinase activity or the lipid composition of the choline-resistant cells but greatly increased the enzyme activities and the phosphatidylcholine content of the choline-sensitive cells. These increases were dose-dependent up to 20 mM choline for choline kinase activities or 10 mM for the PC level. The role played by choline kinase in the survival of tobacco cells, submitted to high choline concentrations (5–30 mM), is discussed.