Regulation of Growth and Invertase Activity by Kinetin and Gibberellic Acid in Developing Avena Internodes

Evidence presented here indicates that there is a complex interaction between kinetin, gibberellin, and sucrose in the regulation of turnover of invertase in vivo. The synthesis of invertase is maintained in the presence of GA₃ and sucrose over relatively long periods of time. Kinetin, on the other hand, inhibits the full development of invertase activity seen in the sucrose and gibberellin control treatments. Moreover, the peak in invertase activity occurs earlier with kinetin treatment. During invertase turnover, once the peak is reached, kinetin enhances the rate of decay of enzyme activity relative to synthesis. The regulatory significance of invertase in intercalary growth and possible modes of kinetin action in this process are discussed.