National Key Laboratory of Plant Molecular Genetics (NKLPMG), CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology (SIPPE), Chinese Academy of Sciences, 200031 Shanghai, P. R. China; Shanghai College of Life Science, University of Chinese Academy of Sciences, Shanghai 200031, P. R. China.
Department of Bioinformatics, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China.
Dev Cell. 2018 Feb 26;44(4):512-523.e5. doi: 10.1016/j.devcel.2017.12.028. Epub 2018 Feb 1.
UV-B light (UV-B radiation) is known to inhibit plant growth, but the mechanism is not well understood. UVR8 (UV RESISTANCE LOCUS 8) is a UV-B light photoreceptor that mediates UV-B light responses in plants. We report here that UV-B inhibits plant growth by repressing plant steroid hormone brassinosteroid (BR)-promoted plant growth. UVR8 physically interacts with the functional dephosphorylated BES1 (BRI1-EMS-SUPPRESSOR1) and BIM1 (BES1-INTERACTING MYC-LIKE 1) transcription factors that mediate BR-regulated gene expression and plant growth to inhibit their activities. Genome-wide gene expression analysis defined a BES1-dependent UV-B-regulated transcriptome, which is enriched with genes involved in cell elongation and plant growth. We further showed that UV-B-activated and nucleus-localized UVR8 inhibited the DNA-binding activities of BES1/BIM1 to directly regulate transcription of growth-related genes. Our results therefore establish that UVR8-BES1/BIM1 interaction represents an early photoreceptor signaling mechanism in plants and serves as an important module integrating light and BR signaling.
UV-B 光（UV-B 辐射）已知能抑制植物生长，但机制尚不清楚。UVR8（UV 抗性基因座 8）是一种 UV-B 光光受体，介导植物中的 UV-B 光反应。我们在这里报告，UV-B 通过抑制植物甾体激素油菜素内酯（BR）促进的植物生长来抑制植物生长。UVR8 与功能去磷酸化的 BES1（BRI1-EMS-SUPPRESSOR1）和 BIM1（BES1-INTERACTING MYC-LIKE 1）转录因子物理相互作用，这些转录因子介导 BR 调控的基因表达和植物生长，以抑制其活性。全基因组基因表达分析定义了一个 BES1 依赖的 UV-B 调控的转录组，该转录组富含参与细胞伸长和植物生长的基因。我们进一步表明，UV-B 激活和核定位的 UVR8 抑制 BES1/BIM1 的 DNA 结合活性，直接调节与生长相关基因的转录。因此，我们的研究结果确立了 UVR8-BES1/BIM1 相互作用代表了植物中早期光受体信号机制，并作为整合光和 BR 信号的重要模块。
