The CmBBX8-CmFTL1 regulatory module is a key determinant in the transition from vegetative growth to reproductive development in summer-flowering chrysanthemum. However, the detailed regulatory mechanism of CmBBX8-mediated flowering remains elusive. In this study, we revealed that RADICAL-INDUCED CELL DEATH 1 (CmRCD1) physically associated with CmBBX8 through bimolecular fluorescence complementation (BiFC), pulldown and Coimmunoprecipitation (CoIP) assays. Furthermore, the RCD1-SRO1-TAF4 (RST) domain of CmRCD1 and the B-box of CmBBX8 mediated their interaction. In addition, Luciferase (LUC) assays and electrophoretic mobility shift assay (EMSAs) showed that CmRCD1 repressed the transcriptional activity of CmBBX8 and interfered with its binding to the CmFTL1 promoter, thereby leading to delayed flowering in the summer chrysanthemum ‘Yuuka’. These results provide insight into the molecular framework of CmRCD1-CmBBX8-mediated flowering in chrysanthemum.

中文翻译：

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CmRCD1通过直接与夏菊CmBBX8相互作用抑制开花

CmBBX8-CmFTL1 调节模块是夏季开花菊花从营养生长向生殖发育过渡的关键决定因素。然而，CmBBX8 介导的开花的详细调控机制仍然难以捉摸。在这项研究中，我们通过双分子荧光互补 (BiFC)、下拉和免疫共沉淀 (CoIP) 测定揭示了自由基诱导的细胞死亡 1 (CmRCD1) 与 CmBBX8 物理相关。此外，CmRCD1 的 RCD1-SRO1-TAF4 (RST) 结构域和 CmBBX8 的 B-box 介导了它们的相互作用。此外，荧光素酶 (LUC) 测定和电泳迁移率变动测定 (EMSAs) 表明 CmRCD1 抑制 CmBBX8 的转录活性并干扰其与CmFTL1促进剂，从而导致夏季菊花'Yuuka'延迟开花。这些结果提供了对 CmRCD1-CmBBX8 介导的菊花开花的分子框架的深入了解。