The blue-light receptor cryptochrome 1 (CRY1) primarily mediates blue-light inhibition of hypocotyl elongation in Arabidopsis. However, the underlying mechanisms remain largely elusive. We report here that CRY1 inhibits hypocotyl elongation by repressing brassinosteroid (BR) signaling. A genetic interaction assay reveals the negative regulatory effect of CRY1 on the function of BZR1, a core transcription factor in the BR signaling pathway. We demonstrated that CRY1 interacts with the DNA-binding domain of BZR1 to interfere with the DNA-binding ability of BZR1, and represses its transcriptional activity. Furthermore, we found that CRY1 promotes the phosphorylation of BZR1 and inhibits the nuclear accumulation of BZR1. Interestingly, we discovered that CRY1 interacts with the GSK3-like kinase BIN2 and enhances the interaction of BIN2 and BZR1 in a light-dependent manner. Our findings revealed that CRY1 negatively regulates the function of BZR1 through at least two mechanisms: interfering with the DNA-binding ability of BZR1 and promoting the phosphorylation of BZR1. Therefore, we uncover a novel CRY1-BIN2-BZR1 regulatory module that mediates crosstalk between blue light and BR signaling to coordinate plant growth in Arabidopsis.

蓝光受体隐色素1（CRY1）主要介导拟南芥中下胚轴伸长的蓝光抑制。但是，基本机制仍然难以捉摸。我们在这里报告，CRY1通过抑制油菜素类固醇（BR）信号传导抑制下胚轴伸长。遗传相互作用测定揭示了CRY1对BR信号通路中的核心转录因子BZR1的功能的负调控作用。我们证明了CRY1与BZR1的DNA结合域相互作用，以干扰BZR1的DNA结合能力，并抑制其转录活性。此外，我们发现CRY1促进BZR1的磷酸化并抑制BZR1的核积累。有趣的是，我们发现CRY1与GSK3样激酶BIN2相互作用，并以光依赖的方式增强BIN2和BZR1的相互作用。我们的发现表明，CRY1至少通过两种机制负调节BZR1的功能：干扰BZR1的DNA结合能力和促进BZR1的磷酸化。因此，我们发现了一种新型的CRY1-BIN2-BZR1调节模块，该模块调节蓝光和BR信号之间的串扰，以协调植物的生长。拟南芥。