Loss-of-function of a rice brassinosteroid biosynthetic enzyme, C-6 oxidase, prevents the organized arrangement and polar elongation of cells in the leaves and stem
Loss-of-function of a rice brassinosteroid biosynthetic enzyme, C-6 oxidase, prevents the organized arrangement and polar elongation of cells in the leaves and stem
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DOI：
10.1046/j.1365-313x.2002.01438.x
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发表时间：
2002-11-01
期刊：
影响因子：
7.2
通讯作者：
Matsuoka, M
中科院分区：
文献类型：
--
作者：
Hong, Z;Ueguchi-Tanaka, M;Matsuoka, M
双子叶植物油菜素内酯（BR）相关突变体的分子遗传学和生理学研究表明，BR在植物正常生长发育中起重要作用。然而，除了对BR信号部分不敏感的水稻突变体的表型分析外，对BR在单子叶植物（禾本科植物）中的功能知之甚少。为了研究BR在单子叶植物中的功能，我们鉴定并鉴定了水稻BR缺陷突变体，BR缺陷矮秆1（brd 1）。brd 1突变体在器官发育和生长方面表现出一系列异常，其中最引人注目的是茎和叶伸长的缺陷。光学显微镜观察表明，这种异常主要是由于叶和干细胞的组织和极性伸长失败。BR化合物在brd 1突变体中的积累曲线表明，这些植物可能缺乏BR C-6氧化酶的活性。因此，我们克隆了水稻基因OsDWARF，它与番茄C-6氧化酶基因DWARF具有高度的序列相似性。将野生型OsDWARF基因导入brd 1中，挽救了突变体的异常表型。OsDWARF基因在所有检测组织中均低水平表达，且在叶鞘中优先表达，且表达受油菜素处理的负调控。在此基础上，我们讨论了BR在水稻中的生物学功能。
Molecular genetic and physiological studies on brassinosteroid (BR)-related mutants of dicot plants have revealed that BRs play important roles in normal plant growth and development. However, little is known about the function of BR in monocots (grasses), except for the phenotypic analysis of a rice mutant partially insensitive to BR signaling. To investigate the function of BR in monocots, we identified and characterized BR-deficient mutants of rice, BR-deficient dwarf1 (brd1). The brd1 mutants showed a range of abnormalities in organ development and growth, the most striking of which were defects in the elongation of the stem and leaves. Light microscopic observations revealed that this abnormality was primarily owing to a failure in the organization and polar elongation of the leaf and stem cells. The accumulation profile of BR compounds in the brd1 mutants suggested that these plants may be deficient in the activity of BR C-6 oxidase. Therefore, we cloned a rice gene, OsDWARF, which has a high sequence similarity to the tomato C-6 oxidase gene, DWARF. Introduction of the wild-type OsDWARF gene into brd1 rescued the abnormal phenotype of the mutants. The OsDWARF gene was expressed at a low level in all of the examined tissues, with preferential expression in the leaf sheath, and the expression was negatively regulated by brassinolide treatment. On the basis of these findings, we discuss the biological function of BRs in rice plants.