Department of Botany, University of Michigan, Ann Arbor, Michigan 48104.
Plant Physiol. 1968 Jan;43(1):29-34. doi: 10.1104/pp.43.1.29.
Gibberellic acid (GA(3)) induces invertase activity within 6 hours in Avena stem segments that are incubated in the dark at 23 degrees . The maximum amount of promotion is about 5 times that of invertase activity in untreated segments. GA(3) causes significant promotion of invertase activity at concentrations as low as 3 x 10(-5) mum GA(3). The increase in invertase activity elicited by GA(3) between 3 x 10(-5) mum and 300 mum closely parallels the growth promotion that is caused by GA(3) over this concentration range. In control segments, invertase activity rises steeply during the first 6 hours of incubation, then decays slowly between 12 and 48 hours. In GA(3)-treated segments, the invertase activity also rises during the first 6 hours, parallel to that in control segments and continues to rise during the next 42 hours. These changes in invertase activity during 48-hour incubation periods do not parallel the changes in growth that occur in control and GA(3)-treated segments. Cycloheximide at 10 mug/ml abolishes all GA(3)-promoted growth and invertase activity in these segments. Actinomycin D at 40 and 80 mug/ml decreases GA(3)-promoted growth by 20% and invertase activity by 38 and 44%, respectively. The data clearly support the idea that protein synthesis is necessary for GA(3)-promoted growth and invertase activity in Avena stem segments.
赤霉素（GA（3））在 23 度黑暗条件下孵育的燕麦茎段中，6 小时内诱导转化酶活性。促进的最大量约为未经处理的片段中转化酶活性的 5 倍。GA（3）在低至 3 x 10（-5）mum GA（3）的浓度下就会引起显著的促进转化酶活性。GA（3）在 3 x 10（-5）mum 和 300 mum 之间引起的转化酶活性的增加与 GA（3）在该浓度范围内引起的生长促进密切相关。在对照段中，转化酶活性在孵育的前 6 小时内急剧上升，然后在 12 至 48 小时之间缓慢下降。在 GA（3）处理的片段中，转化酶活性也在第一个 6 小时内上升，与对照段平行，并在接下来的 42 小时内继续上升。在 48 小时孵育期间，转化酶活性的这些变化与对照和 GA（3）处理的片段中发生的生长变化不平行。10 微克/毫升的环己酰亚胺完全消除这些片段中所有 GA（3）促进的生长和转化酶活性。40 和 80 微克/毫升的放线菌素 D 使 GA（3）促进的生长分别减少 20%和转化酶活性减少 38%和 44%。这些数据清楚地支持了这样的观点，即蛋白质合成是 GA（3）促进燕麦茎段生长和转化酶活性所必需的。
