Brassinosteroid Regulates Cell Elongation by Modulating Gibberellin Metabolism in Rice
Brassinosteroid Regulates Cell Elongation by Modulating Gibberellin Metabolism in Rice
复制标题
油菜素类固醇通过调节水稻中的赤霉素代谢来调节细胞伸长
DOI：
10.1105/tpc.114.132092
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发表时间：
2014-11-01
期刊：
影响因子：
11.6
通讯作者：
Chu, Chengcai
中科院分区：
文献类型：
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作者：
Tong, Hongning;Xiao, Yunhua;Chu, Chengcai
油菜素类固醇（BR）和赤霉素（GA）是调节植物细胞伸长的两种主要激素。其中任何一个缺陷都会导致植物生长减少和矮化。然而，它们在水稻（Oryza sativa）中的关系仍然未知。在这里，我们证明了 BR 通过调节水稻中的 GA 代谢来调节细胞伸长。在生理条件下，BR通过调节GA代谢基因的表达来促进GA积累，刺激细胞伸长。 BR 极大地诱导 D18/GA3ox-2（GA 生物合成基因之一）的表达，导致 GA(1) 水平增加，GA(1) 是水稻幼苗中具有生物活性的 GA。因此，d18 和功能丧失的 GA 信号突变体均降低了 BR 敏感性。当施用过量的活性BR时，激素主要通过上调GA失活基因GA2ox-3诱导GA失活，并抑制BR生物合成，导致激素水平下降和生长抑制。作为一种反馈机制，GA 广泛抑制 BR 生物合成和 BR 反应。 GA 处理可降低植物中增大的叶角，并增强 BR 生物合成或信号传导。我们的结果揭示了一种以前未知的 BR 和 GA 串扰依赖于组织和激素水平的机制，这极大地增进了我们对作物中激素作用的理解，并且与拟南芥中的激素作用有很大不同。
Brassinosteroid (BR) and gibberellin (GA) are two predominant hormones regulating plant cell elongation. A defect in either of these leads to reduced plant growth and dwarfism. However, their relationship remains unknown in rice (Oryza sativa). Here, we demonstrated that BR regulates cell elongation by modulating GA metabolism in rice. Under physiological conditions, BR promotes GA accumulation by regulating the expression of GA metabolic genes to stimulate cell elongation. BR greatly induces the expression of D18/GA3ox-2, one of the GA biosynthetic genes, leading to increased GA(1) levels, the bioactive GA in rice seedlings. Consequently, both d18 and loss-of-function GA-signaling mutants have decreased BR sensitivity. When excessive active BR is applied, the hormone mostly induces GA inactivation through upregulation of the GA inactivation gene GA2ox-3 and also represses BR biosynthesis, resulting in decreased hormone levels and growth inhibition. As a feedback mechanism, GA extensively inhibits BR biosynthesis and the BR response. GA treatment decreases the enlarged leaf angles in plants with enhanced BR biosynthesis or signaling. Our results revealed a previously unknown mechanism underlying BR and GA crosstalk depending on tissues and hormone levels, which greatly advances our understanding of hormone actions in crop plants and appears much different from that in Arabidopsis thaliana.