Effects of pH on the induction of phosphoenolpyruvate carboxylase kinase in Kalanchoë fedtschenkoi.
Previous work has shown that an increase in cytosolic pH plays an important role in the induction of phosphoenolpyruvate carboxylase (PEPc) kinase by light in C(4) plants. The potential involvement of a similar effect in the induction of PEPc kinase in the Crassulacean acid metabolism (CAM) plant Kalanchoë fedtschenkoi was assessed using leaf disks. Treatment of disks with the weak base NH(4)Cl did not affect induction of the kinase. Prolonged treatment of disks with weak acids prevented both decarboxylation of malate during the day and induction of the kinase in the following night, but short treatments had no effect. The data are consistent with the view that a high cytosolic malate content can prevent induction of phosphoenolpyruvate carboxylase kinase. Changes in cytosolic pH may affect induction of the kinase in CAM plants by a secondary effect rather than as part of a primary signalling pathway.
Paterson
KM
Plant Molecular Science Group, Division of Biochemistry and Molecular Biology, Bower Building, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK
Nimmo
HG