Induction of PEP carboxylase and Crassulacean acid metabolism by gibberellic acid in Mesembryanthemum crystallinum

The induction of Crassulacean acid metabolism in Mesembryanthemum crystalli num was investigated in response to foliar application of gibberellic acid (GA), After 5 weeks of treatment, GA-treated plants showed 1.7- to almost a I-fold increase of phosphoenolpyruvate carboxylase (PEPcase) activity with a concomitant increase in acid metabolism when compared to control plants. Immunoblot analysis indicated an increase in the PEPcase protein similar t o that of salt treatment while Rubisco did not show a similar rise. The res ults indicate that exogenously applied GA accelerates plant developmental e xpression of PEPcase and Crassulacean acid metabolism in M. crystallinum.