National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources/Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crops in South China, Ministry of Agriculture/College of Horticulture, South China Agricultural University, Guangzhou, 510642, China.
New Phytol. 2019 Aug;223(3):1407-1419. doi: 10.1111/nph.15866. Epub 2019 Jun 20.
BRI1-EMS-SUPPRESSOR 1 (BES1) functions as a key regulator in the brassinosteroid (BR) pathway that promotes plant growth. However, whether BES1 is involved in photoperiodic flowering is unknown. Here we report that BES1 acts as a positive regulator of photoperiodic flowering, but it cannot directly bind FLOWERING LOCUS T (FT) promoter. BR ENHANCED EXPRESSION 1 (BEE1) is the direct target of BES1 and acts downstream of BES1. BEE1 is also a positive regulator of photoperiodic flowering. BEE1 binds directly to the FT chromatin to activate the transcription of FT and promote flowering initiation. More importantly, BEE1 promotes flowering in a blue light photoreceptor CRYPTOCHROME 2 (CRY2) partially dependent manner, as it physically interacts with CRY2 under the blue light. Furthermore, BEE1 is regulated by both BRs and blue light. The transcription of BEE1 is induced by BRs, and the BEE1 protein is stabilized under the blue light. Our findings indicate that BEE1 is the integrator of BES1 and CRY2 mediating flowering, and BES1-BEE1-FT is a new signaling pathway in regulating photoperiodic flowering.
BRI1-EMS-SUPPRESSOR 1 (BES1) 作为油菜素内酯 (BR) 途径中的关键调节剂，促进植物生长。然而，BES1 是否参与光周期开花尚不清楚。在这里，我们报告 BES1 作为光周期开花的正调节剂，但其不能直接结合 FLOWERING LOCUS T (FT) 启动子。BR 增强表达 1 (BEE1) 是 BES1 的直接靶标，并且作用于 BES1 的下游。BEE1 也是光周期开花的正调节剂。BEE1 直接结合到 FT 染色质上，激活 FT 的转录，促进开花起始。更重要的是，BEE1 以部分依赖于蓝光受体隐花色素 2 (CRY2) 的方式促进开花，因为它在蓝光下与 CRY2 发生物理相互作用。此外，BEE1 受 BR 和蓝光调控。BEE1 的转录受 BR 诱导，BEE1 蛋白在蓝光下稳定。我们的研究结果表明，BEE1 是 BES1 和 CRY2 介导开花的整合因子，BES1-BEE1-FT 是调控光周期开花的新信号通路。
