Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
New Phytol. 2018 Oct;220(2):488-501. doi: 10.1111/nph.15331. Epub 2018 Jul 16.
Plant growth and development are highly coordinated by hormones, including brassinosteroid (BR) and gibberellin (GA). Although much progress has been made in understanding the fundamental signaling transduction in BR and GA, their relationship remains elusive in rice. Here, we show that BR suppresses the level of OsmiR159d, which cleaves the target OsGAMYBL2 gene. The OsmiR159d-OsGAMYBL2 pair functions as an early BR-responsive module regulating the expression of BU1, a BR-regulated gene involved in BR signaling, and CPS1 and GA3ox2, two genes in GA biosynthesis, by binding to the promoters of these genes. Furthermore, OsGSK2, a key negative player in BR signaling, interacts with OsGAMYBL2 and prevents it from being degraded under 24-epibrassinolide treatment, whereas SLR1, a rice DELLA protein negatively regulating GA signaling, interacts with OsGAMYBL2 and prevents OsGAMYBL2 from binding to the target gene promoter. GA signaling induces degradation of OsGAMYBL2 and, consequently, enhances BR signaling. These results demonstrate that a BR-responsive module acts as a common component functioning in both BR and GA pathways, which connects BR signaling and GA biosynthesis, and thus coordinates the regulation of BR and GA in plant growth and development.
植物的生长和发育受到激素的高度调控，其中包括油菜素内酯（BR）和赤霉素（GA）。尽管人们在理解 BR 和 GA 的基本信号转导方面已经取得了很大的进展，但在水稻中，它们之间的关系仍然难以捉摸。在这里，我们表明 BR 抑制 OsmiR159d 的水平，OsmiR159d 可以切割靶基因 OsGAMYBL2。OsmiR159d-OsGAMYBL2 对作为一个早期的 BR 反应模块，通过结合这些基因的启动子，调节 BR 信号转导涉及的 BR 调节基因 BU1、参与 BR 信号转导的 CPS1 和 GA3ox2 的表达。此外，BR 信号通路中的关键负调控因子 OsGSK2 与 OsGAMYBL2 相互作用，阻止其在 24-表油菜素内酯处理下降解，而负调控 GA 信号通路的水稻 SLR1 蛋白与 OsGAMYBL2 相互作用，阻止 OsGAMYBL2 结合靶基因启动子。GA 信号诱导 OsGAMYBL2 的降解，从而增强 BR 信号。这些结果表明，BR 反应模块作为一个共同的组成部分，在 BR 和 GA 途径中发挥作用，连接 BR 信号和 GA 生物合成，从而协调 BR 和 GA 在植物生长和发育中的调控。
