Effects Of Treatments With Abscisic Acid And Reagents Of Reversible Phosphorylation On Activities Of Carbohydrate Metabolic Enzymes In Developing Grape Berry And Apple Fruit

Abscisic acid (ABA) is a vital plant hormone that plays an important role in various plant developmental processes including fruit ripening and carbohydrate partitioning in fruit. This study aims at a better insight into the ABA action mechanism. By incubating the fruit discs in the ABA-contained medium, the results showed that ABA strongly activated the fruit soluble acid invertase. The ABA-induced acid invertase activation appeared significantly 4 hours after 20umol/L ABA incubation in grape berry and 3 hours after 20umol/L ABA in apple fruit. Further experiments were conducted to assess possible role of protein reversible phosphorylation in the ABA-induced acid invertase activation. By adding inhibitors of protein kinase and protein phosphatase, the results indicated that there may exist a complex regulation mechanism involving various protein kinases and protein phosphatases that may interact among them to constitute a complex signaling cascades. The protein synthesis inhibitor cycloheximide and mRNA transcription inhibitor Actidione D were also used to show futher mechanism of ABA action. In grape berry acid invertase activity was suppressed and the inhibitors annulled ABA activation effects. In apple fruit ABA effects were strengthened instead. By using acid phosphatase in the crude extract, dephosporylation helped to enhance the activity of acid invertase.