Regulation of Isoprenoid Biosynthesis in Higher Plants

这项研究的总体目标是了解在植物生命中具有重要生理意义的二萜类物质的生物合成调节机制。第一个实验目标是高岭烯合成酶，它是植物激素赤霉素家族生物合成途径中的关键调节酶。正在尝试一种新的方法来评估这项活动的水平。考伦合成酶复合体的成分将被提纯至均一，制备抗体并分离出cdna克隆。然后，这些工具将被用来测量植物器官中可翻译和可完全杂交的Kaurene合成酶mRNAs的水平，以及它们在不同生理环境下的变化。水稻二萜类植物保卫素的生物合成途径是第二个值得关注的领域。这些生物合成途径的生化特征将进一步确定。启动二萜类植物保卫素生物合成的激发子分子的性质将被研究。并将研究转录调控在参与二萜烃中间体环化的酶的表达中的作用。这些结果将有助于我们了解植物对环境和生物胁迫的反应方式。代谢物通常被描述为次生代谢物。这些物质似乎服务于生产它们的有机体，发挥专门的调节作用，使有机体能够适应与病原体、捕食者和竞争对手的入侵有关的环境变化和生物压力。与这一观点一致的是，许多从高等植物中分离出来的环状二萜类化合物已被证明具有生理活性。这项研究中考虑的二萜类物质就是例子。Ent-Kaurene是天然植物生长调节剂赤霉素族的环状二萜前体，而酪蛋白、麦芽内酯和谷氨酰胺是被认为在寄主植物对微生物病原体的抗性中起重要作用的植物保留素。

The general objective of this research is to develop an understanding of the mechanisms of regulation of the biosynthesis of diterpenoid substances of physiological importance in the life of the plant. The first experimental target is kaurene synthetase, a key regulatory enzyme in the biosynthetic pathway leading to the gibberellin family of plant hormones. A new approach to assessing the levels of this activity is being attempted. Components of the kaurene synthetase complex will be purified to homogenity, antibodies prepared and cDNA clones isolated. These tools will then be utilized to measure the levels of translatable and total hybridizable kaurene synthetase mRNAs in plant organs, and their changes under different physiological circumstances. The biosynthetic pathways involved in diterpenoid phytoalexin biosynthesis in rice (Oryza sativa) is a second area of interest. The biochemical characteristics of these biosynthetic pathways will be further defined. The nature of elicitor molecules that initiate diterpenoid phytoalexin biosynthesis will be investigated. And the role of transcriptional regulation in the expression of the enzymes involved in cyclization of diterpene hydrocarbon intermediates will be investigated. These results will contribute to our knowledge of the manner in which plants respond to environmental and biological stresses.%%% Cyclic diterpenoid metabolites are often characterized as secondary metabolites. Such substances appear to serve the organism that produces them in specialized regulatory roles that enable the organism to adapt to environmental changes and biological stresses associated with encroachments by pathogens, predators and competitors. Consistent with this view, many cyclic diterpenoid compounds isolated from higher plants have been shown to be physiologically active. The diterpenoid substances whose metabolism is being considered in this research are examples. ent-Kaurene is the cyclic diterpene precursor of the gibberellin family of natural plant growth regulators, while casbene, the momilactones and the oryzalexins are phytoalexins that are thought to be important in the host plant's resistance to microbial pathogens.***//