Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Plant Sci. 2020 Mar;292:110378. doi: 10.1016/j.plantsci.2019.110378. Epub 2019 Dec 13.
In plants, the organ size is one of the most important features and regulated by an elaborate developmental program involving both internal and external signals. The steroidal hormone brassinosteroid (BR) plays an important role in regulating the organ size. BRASSINAZOLE RESISTANT 1 (BZR1) is one of important transcription factors that regulate organ size in BR signal pathway in Arabidopsis. The function of BZR1 on organ size is well characterized in Arabidopsis, but poorly understood in maize (Zea mays). To understand the mechanism of intrinsic organ size regulated by BZR1 during organogenesis, we identified the maize BZR1 and examined its function in Arabidopsis. Overexpression of ZmBZR1 displayed phenotypes of enlarged cotyledons, rosette leaves, floral organ and seed size in Arabidopsis. The cells in rosette leaves as well as other organs in transgenic ZmBZR1 lines were dramatically larger and longer than those in Col-0. ChIP and RNA-seq analysis showed ZmBZR1 can directly bind to the promoter region of organ size related genes, Germination Repression and Cell Expansion receptor-like kinase (GRACE) and KIP-RELATED PROTEIN6 (KRP6) to regulate their expression, suggesting ZmBZR1 is required for the progressive increase in cells during Arabidopsis development. Collectively, our findings provide significant insights into the mechanisms underlying regulation of organ size mediated by maize BZR1.
在植物中，器官大小是最重要的特征之一，它受到涉及内部和外部信号的精细发育程序的调控。甾体激素油菜素内酯（BR）在调节器官大小方面起着重要作用。BRASSINAZOLE RESISTANT 1（BZR1）是调节拟南芥 BR 信号通路中器官大小的重要转录因子之一。BZR1 对器官大小的功能在拟南芥中得到了很好的描述，但在玉米（Zea mays）中了解甚少。为了了解 BZR1 在器官发生过程中调节内在器官大小的机制，我们鉴定了玉米 BZR1 并研究了其在拟南芥中的功能。ZmBZR1 的过表达在拟南芥中表现出子叶增大、莲座叶、花器官和种子大小的表型。转基因 ZmBZR1 系的莲座叶和其他器官中的细胞明显大于 Col-0 中的细胞。ChIP 和 RNA-seq 分析表明，ZmBZR1 可以直接结合到与器官大小相关基因的启动子区域，如萌发抑制和细胞扩展受体样激酶（GRACE）和 KIP-RELATED PROTEIN6（KRP6），以调节它们的表达，表明 ZmBZR1 是拟南芥发育过程中细胞逐渐增加所必需的。总之，我们的研究结果为玉米 BZR1 介导的器官大小调控机制提供了重要的见解。
