Northeast Institute of Geography and Agroecology, Key Laboratory of Soybean Molecular Design Breeding, Chinese Academy of Sciences, Harbin 150081, China.
Graduate University of Chinese Academy of Sciences, Beijing 100049, China.
Plant Physiol. 2017 Nov;175(3):1337-1349. doi: 10.1104/pp.17.00946. Epub 2017 Sep 11.
Brassinosteroids (BRs) are a class of steroid hormones regulating multiple aspects of plant growth, development, and adaptation. Compared with extensive studies in Arabidopsis (), the mechanism of BR signaling in rice () is less understood. Here, we identified OsWRKY53, a transcription factor involved in defense responses, as an important regulator of rice BR signaling. Phenotypic analyses showed that overexpression led to enlarged leaf angles and increased grain size, in contrast to the erect leaves and smaller seeds in mutant. In addition, the exhibited decreased BR sensitivity, whereas overexpression plants were hypersensitive to BR, suggesting that OsWRKY53 positively regulates rice BR signaling. Moreover, we show that OsWRKY53 can interact with and be phosphorylated by the OsMAPKK4-OsMAPK6 cascade, and the phosphorylation is required for the biological function of OsWRKY53 in regulating BR responses. Furthermore, we found that BR promotes OsWRKY53 protein accumulation but represses transcript level. Taken together, this study revealed the novel role of OsWRKY53 as a regulator of rice BR signaling and also suggested a potential role of OsWRKY53 in mediating the cross talk between the hormone and other signaling pathways.
油菜素内酯（BRs）是一类甾体激素，调节植物生长、发育和适应的多个方面。与拟南芥（Arabidopsis）广泛的研究相比，BR 信号在水稻（Rice）中的机制了解较少。在这里，我们鉴定了一个参与防御反应的转录因子 OsWRKY53，它是水稻 BR 信号的一个重要调节因子。表型分析表明，过表达导致叶片角度增大和粒重增加，而 突变体则表现为叶片直立和种子变小。此外，表现出对 BR 的敏感性降低，而 过表达植株对 BR 敏感，表明 OsWRKY53 正向调节水稻 BR 信号。此外，我们表明 OsWRKY53 可以与 OsMAPKK4-OsMAPK6 级联相互作用并被其磷酸化，并且磷酸化是 OsWRKY53 调节 BR 反应的生物学功能所必需的。此外，我们发现 BR 促进 OsWRKY53 蛋白积累但抑制 转录水平。总之，本研究揭示了 OsWRKY53 作为水稻 BR 信号调节剂的新作用，并暗示了 OsWRKY53 在激素与其他信号通路之间的串扰中发挥作用的潜力。
