Analysis of Brassinosteroid Biosynthesis in Arabidopsis thaliana

油菜素类固醇被认为是一种调节植物生长的植物激素。内源油菜素内酯含量缺乏的拟南芥矮秆突变体已被用于油菜素内酯生物合成的研究。在这项研究中，为了阐明拟南芥中油菜素类固醇生物合成的调控，本研究对以下对象进行了研究：1)建立了完整植物代谢研究的实验条件。我们已经对底物油菜素类化合物处理拟南芥完整植株的几种方法进行了试验。在使用液体苗木培养的系统中观察到最高的效率。微量注射完全无效，直接注射蓖麻素对拟南芥的代谢活性较弱。2)油菜素内酯生物合成缺陷矮秆突变体的鉴定。在T-DNA插入突变体中发现一个矮秆突变体，其表型与油菜素类固醇突变体相似。油菜素类固醇的应用和内源油菜素类固醇水平的分析表明，它是一种新的油菜素类固醇突变体，其对蓖麻甾酮的代谢活性存在缺陷。人们试图克隆被T-DNA插入干扰的基因，尽管目前还没有实现这一点。这项研究将在我们的克隆工作取得成功后发表。

Brassinosteroid has been recognized as a plant hormone that regulates growth of plants. Dwarf mutants of Arabidopsis thaliana that are deficient in endogenous brassinosteroid levels have been used for studies on the biosynthesis of brassinosteroid. In this study, following subjects have been examined to clarify the regulation of the biosynthesis of brassinosteroid in Arabidopsis.1)Establishment of experimental conditions for metabolic studies with intact plants. We have tested several methods for the treatment of substrate brassinosteroids to the intact plants of Arabidopsis. The highest efficiency was observed in the system using a liquid culture of seedlings. Micro-injection was not effective at all, and slight metabolic activity was observed in the direct injection of castasterone into Arabidopsis stems.2)Characterization of novel dwarf mutant that has defect in brassinosteroidbiosynthesis.A dwarf mutant was found in the T-DNA insertion mutant lines, which had similar phenotype with brassinosteroid mutants. Application of brassinosteroids and analysis of endogenous brassinosteroid levels revealed that it is a novel brassinosteroid mutant that has defect in the metabolic activity of typhasterol to castasterone. Cloning of the gene that is disrupted by the insertion of T-DNA was attempted, although it has not been achieved yet. This study will be published after we get successful results in the cloning work.