The Arabidopsis dwf7/ste1 mutant is defective in the Δ7 sterol C-5 desaturation step leading to brassinosteroid biosynthesis
The Arabidopsis dwf7/ste1 mutant is defective in the Δ7 sterol C-5 desaturation step leading to brassinosteroid biosynthesis
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DOI：
10.1105/tpc.11.2.207
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发表时间：
1999-02-01
期刊：
影响因子：
11.6
通讯作者：
Feldmann, KA
中科院分区：
文献类型：
--
作者：
Choe, SW;Noguchi, T;Feldmann, KA
油菜素内酯（BR）生物合成基因的损伤导致植物的特征性矮化表型。了解BR生物合成的调控需要继续分离和表征BR生物合成相关基因的突变体。在这里，我们分析了一个新的BR生物合成位点，侏儒7 （dwf7）。BR生物合成中间体的饲养研究以及内源性BR和甾醇生物合成中间体水平的分析表明，dwf7-1的缺陷步骤存在于甾醇生物合成途径中24-亚甲基胆固醇生成之前。此外，用c -13标记的甲羟戊酸和压实蛋白进行喂养研究的结果表明，缺陷步骤具体是Delta(7)甾醇C-5去饱和，这表明dwf7是先前克隆的STEROL1 （STE1）基因的等位基因。对两个dwf7突变体的STE1位点测序发现，在第一（dwf7-2）和第三（dwf7-1）外显子中存在过早终止密码子。因此，在dwf7中，BRs的减少是由于底物固醇的缺乏，这是dwf7矮化表型的直接原因。
Lesions in brassinosteroid (BR) biosynthetic genes result in characteristic dwarf phenotypes in plants. Understanding the regulation of BR biosynthesis demands continued isolation and characterization of mutants corresponding to the genes involved in BR biosynthesis. Here, we present analysis of a novel BR biosynthetic locus, dwarf7 (dwf7). Feeding studies with BR biosynthetic intermediates and analysis of endogenous levels of BR and sterol biosynthetic intermediates indicate that the defective step in dwf7-1 resides before the production of 24-methylenecholesterol in the sterol biosynthetic pathway. Furthermore, results from feeding studies with C-13-labeled mevalonic acid and compactin show that the defective step is specifically the Delta(7) sterol C-5 desaturation, suggesting that dwf7 is an allele of the previously cloned STEROL1 (STE1) gene. Sequencing of the STE1 locus in two dwf7 mutants revealed premature stop codons in the first (dwf7-2) and the third (dwf7-1) exons. Thus, the reduction of BRs in dwn is due to a shortage of substrate sterols and is the direct cause of the dwarf phenotype in dwf7.