Differential effect of gibberellic Acid on enhancement and release of Acid phosphatase in barley half-seeds.

Acid phosphatase activity in half-seeds of a huskless barley (Hordeum vulgare L. cv. Ehimehadaka No. 1) increased linearly after a lag period of about 12 h. Gibberellic acid (GA(3)) lowered the acid phosphatase activity in half-seeds after about 12 h, while it increased the enzyme activity in the ambient medium, resulting in a similar level of the total enzyme activity. A marked increase in the activity of particular acid phosphatase isozymes in half-seeds was observed regardless of the presence or absence of GA(3). On the contrary, release of each of the identified isozymes from half-seeds into the medium was evidently GA(3)?dependent. These results indicate that at least in this barley variety, GA(3) influences only the release of acid phosphatase. Cycloheximide inhibited both the GA(3)?independent increase in total acid phosphatase activity and the GA(3)?dependent release of the enzyme, suggesting that de novo protein synthesis is involved in both processes.