Similarities Between Gibberellins and Related Compounds in Inducing Acid Phosphatase and Reducing Sugar Release From Barley Endosperm

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Abstract
Barley endosperm halves release acid phosphatase in response to several gibberellins and gibberellin precursors. Seed halves incubated with 10−7m GA3 at 29° begin to release phosphatase after 11 hr and release it for another 26 hr in response to GA3. After 37 hr, the rate of release slows to that of seed halves incubated without GA3. GA3 is active at 10−10m and maximally active at 10−7m. Comparative activity of 12 gibberellins and gibberellin precursors is GA1 = GA3 > GA2 > GA4 = GA7 > GA5 = GA13 > GA14 > GA8 = GA9 > (−)kaurenoic acid > (−)-kaurene. These compounds show the same order of activity and approximately the same relative activity in inducing reducing sugar release as in inducing phosphatase activity. The activity of each compound increases with its presumed position in a biosynthetic pathway leading from kaurene to GA3. This correlation suggests that activity may be a reflection of the efficiency of conversion to an active form within the seed half.