Key Laboratory of Arid and Grassland Agroecology (Ministry of Education), School of Life Sciences, Lanzhou University, Lanzhou Gansu, People's Republic of China.
J Plant Physiol. 2010 Sep 15;167(14):1130-6. doi: 10.1016/j.jplph.2010.03.007. Epub 2010 Apr 28.
In this study, the effects of sucrose on hypocotyl elongation of Arabidopsis seedlings in light and in dark were investigated. Sucrose suppressed the hypocotyl elongation of Arabidopsis seedlings in light, but stimulated elongation in dark. Application of paclobutrazol (PAC, a gibberellin biosynthesis inhibitor) impaired the effects of sucrose on hypocotyl elongation, suggesting that endogenous GAs is required for sucrose-induced hypocotyl elongation in the dark. Exogenous GA(3) application reversed the repression caused by PAC application, indicating that exogenous GA(3) could substitute, at least partially, for endogenous GAs in sucrose-induced hypocotyl elongation. In addition, we found that GA 3-oxidase 1 (GA3ox1), encoding a key enzyme involved in endogenous bioactive GA biosynthesis, was up-regulated by sucrose in the dark, whereas GIBBERELLIN INSENSITIVE DWARF 1a (AtGID1a), encoding a GA receptor and playing an important role during GAs degradation to DELLA proteins (DELLAs, repressors of GA-induced plant growth), was down-regulated. These results imply that endogenous bioactive GA levels are expected to be enhanced, but the degradation of DELLAs was inhibited by sucrose in dark. Thus, our data suggest that the sucrose-induced hypocotyl elongation in the dark does not result from GA-induced degradation of DELLAs. We conclude that sucrose can stimulate hypocotyl elongation of Arabidopsis seedlings in the dark in a GA-dependent manner.
在这项研究中，研究了蔗糖对光下和黑暗中拟南芥幼苗下胚轴伸长的影响。蔗糖抑制光下拟南芥幼苗下胚轴的伸长，但在黑暗中刺激伸长。应用多效唑（PAC，一种赤霉素生物合成抑制剂）削弱了蔗糖对下胚轴伸长的影响，表明内源 GA 是黑暗中蔗糖诱导下胚轴伸长所必需的。外源 GA（3）的应用逆转了 PAC 应用引起的抑制，表明外源 GA（3）至少可以部分替代内源 GAs 在蔗糖诱导的下胚轴伸长中。此外，我们发现，编码参与内源生物活性 GA 生物合成的关键酶的 GA 3-氧化酶 1（GA3ox1）在下胚轴伸长中受蔗糖的上调，而编码 GA 受体的赤霉素不敏感矮化 1a（AtGID1a）在下胚轴伸长中起重要作用，在 GA 降解为 DELLA 蛋白（DELLAs，GA 诱导的植物生长的抑制剂）过程中。这些结果表明，内源生物活性 GA 水平预计会升高，但蔗糖在黑暗中抑制了 DELLA 的降解。因此，我们的数据表明，蔗糖在黑暗中诱导的下胚轴伸长不是由于 GA 诱导的 DELLA 降解所致。我们得出结论，蔗糖可以以 GA 依赖的方式刺激黑暗中拟南芥幼苗的下胚轴伸长。
