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Isolation of photocontrolled gibberellin 3beta-hydroxylase in lettuce seeds.

生菜种子中光控赤霉素 3β-羟化酶的分离。

基本信息

批准号：
03640566
负责人：
INOUE Yasunori
金额：
$ 1.15万
依托单位：
Faculty of Science and Technology, Science University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

Gibberellin was mediated in the photoinduction of lettuce seeds germination. Feeding experiments of ^3H-GAs suggested that the final step of active GA synthesis, namely, 3beta-hydroxylation of GA_<20> to GA_1 was activated by light. The purpose of this research was isolate the 3 hydroxylase from lettuce seeds and to determine the change of activity directly.Enzyme activity of the lettuce seeds homogenate was too low to isolate it caused by the existence of plenty amount of phenolic compounds. Besides, the supply of lettuce seeds was shorted. Therefore, we must change the plant materials from lettuce to Phaseolus virgules.One dwarf variety of P. vergules named "Green dash" was selected from several variety on the viewpoint of photoinhibition of hypocotyl growth. Inhibition rate of hypocotyl growth by white light was age independent between 5 to 10 days after sowing. Effect of light was nearly saturated at 0.4Wm^<-2>. Inhibition rate was linear to the logarithm of irradiation period when it was shorter than 12 hr. Application of GA_3 recover the photoinhibited hypocotyl growth to the dark level. However, growth in the dark was little effected by GA_3. On the other hand, application of GA synthesis inhibitor highly suppress only the growth in the dark. These results suggested that the effect of light was visualize in the length of hypocotyl mediated by gibberellin. Growth inhibition obligated by the application of GA synthesis inhibitor was recovered by the application of GA_3. In this time, about 10 times higher concentration of GA_3 was required for the light grown seedling than dark grown one for full recovery. These results suggested that light induced the reduction of GA level in the hypocotyl and reduced the sensitivity of hypocotyl to GAs.

赤霉素介导生菜种子萌发的光诱导。 3H-GA的饲喂实验表明活性GA合成的最后步骤，即GA_ 20 到GA_1的3β-羟基化被光激活。本研究的目的是从生菜种子中分离出3羟化酶，并直接测定其活性的变化。由于生菜种子匀浆中存在大量酚类化合物，导致酶活性过低，无法分离。此外，生菜种子供应短缺。因此，必须将种植材料由生菜改为菜豆。从光抑制下胚轴生长的角度出发，从多个品种中筛选出一株矮化品种，命名为“Green dash”。播种后5至10天内，白光对下胚轴生长的抑制率与年龄无关。光的效果在0.4Wm 2 -2 处几乎饱和。当照射时间小于12小时时，抑制率与照射时间的对数呈线性关系。应用GA_3将光抑制的下胚轴生长恢复至暗水平。然而，GA_3对黑暗中的生长影响很小。另一方面，GA合成抑制剂的应用仅高度抑制在黑暗中的生长。这些结果表明，光对赤霉素介导的下胚轴长度的影响是可视化的。通过应用GA_3可以恢复由于应用GA合成抑制剂而产生的生长抑制。此时，光生长的幼苗需要比暗生长的幼苗高约 10 倍的 GA_3 浓度才能完全恢复。这些结果表明，光诱导下胚轴中 GA 水平的降低，并降低下胚轴对 GA 的敏感性。