Effect of Exogenous Plant Bioactive Substances on Phleinase Induction in Stem Base of Orchardgrass

Abstract

For elucidation of involvement of bioactive substances in the induction of phleinase in defoliated stem bases of orchardgrass, the effect of exogenously applied substances on the enzyme activity was studied. The induction of phleinase in excised, defoliated and undefoliated stem bases was enhanced by treatment with gibberellic acid, cytokinin, 8-bromoadenosine-3, 5-cyclic monophosphate (8-bromo-CAMP) or theophylline, while not affected by indoleacetic acid, 2, 3, 5-triiodobenzoic acid or 2-chloroethylphosphonic acid. The phleinase induction was suppressed by continuous treatment with abscisic acid (ABA) to excised stems, but not by transient treatment with ABA at defoliation. These results suggest that there is a possibility of involvement of the changes in endogenous concentration of gibberellin, cytokinin, CAMP and ABA in the phleinase induction in the stem bases of orchardgrass after defoliation.