Changes in Activities and Levels of Pyruvate, Orthophosphate Dikinase with Induction of Crassulacean Acid Metabolism in Mesembryanthemum crystallinum L.

Abstract

In Mesembryanthetnum crystallinum L.leaves exhibiting C₃ photosynthesis, Crassulacean acid metabolism (CAM), as characterized by CO₂ uptake during the dark period, was induced by exposing the plant roots to high NaCl concentration over a week. The increase in malate content in the leaves at the end of the dark period correlated with the increases in the activities of phosphoenolpyruvate carboxylase (PEPCase), NADP malic enzyme (NADP-ME) and pyruvate, orthophosphate dikinase (PPDK) which exhibited a maximum about a week after NaCl treatment. It was found that PPDK existed in C₃-M. ctystallinum and the increases in the activities of PEPCase and PPDK were accompanied by the de novo synthesis of these proteins