A brassinosteroid responsive miRNA-target module regulates gibberellin biosynthesis and plant development

First author: Jing Gao; Affiliations: South China Botanical Garden, Chinese Academy of Sciences (中科院华南植物园): Guangzhou, China

Corresponding author: Jianxiong Li

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‐ esponsive module regulating the expression of BU1, a BR‐ egulated 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 (24-表油菜素内酯) 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‐ esponsive 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.

植物生长与发育受到不同激素的共同调控，包括油菜素内酯BR和赤霉素GA。尽管已经有很多BR和GA信号转导方面的研究，但在水稻中这两者之间关系还不清楚。本文的研究显示BR能抑制OsmiR159d的水平，而OsmiR159d能够剪切其靶基因OsGAMYBL2。OsmiR159d‐OsGAMYBL2作为早期的BR响应模块通过结合到基因的启动子区调控BR相关基因BU1及参与GA生物合成相关基因CPS1和GA3ox2。此外，BR信号中的关键负调控子OsGSK2与OsGAMYBL2相互作用，并阻止其在24-表油菜素内酯处理条件下被降解，而GA信号负调控子水稻DELLA蛋白SLR1与OsGAMYBL2相互作用，并阻止其结合到靶基因的启动子区。GA信号诱导OsGAMYBL2的降解，进而增强BR信号。本文的结果揭示了一个BR响应的模块作用于BR和GA通路，通过连接BR信号与GA通路共同调控植物的生长与发育。

通讯：李建雄 (http://sourcedb.scib.cas.cn/zw/rck/200907/t20090713_2066562.html)

个人简介：1990年，华中农业大学，植物遗传育种学士；1995年，华中农业大学，植物遗传育种硕士；1998年，华中农业大学，分子生物学博士。

研究方向：以水稻为材料，研究稻曲病的抗性、miRNA对水稻生长发育的影响及OFP家族基因在水稻生长发育过程及对籽粒形状影响的分子机制。

doi: https://doi.org/10.1111/nph.15331

Journal: New physiologist

First Published: 16 July, 2018

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