State Key Laboratory of Rice Biology, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, Zhejiang 310058, China.
Hainan Yazhou Bay Seed Laboratory, Hainan Institute, Zhejiang University, Sanya, Hainan 572000, China.
Plant Cell. 2023 Sep 27;35(10):3697-3711. doi: 10.1093/plcell/koad190.
FLOWERING PROMOTING FACTOR1 (FPF1), a small protein without any known domains, promotes flowering in several plants; however, its functional mechanism remains unknown. Here, we characterized 2 FPF1-like proteins, FPL1 and FPL7, which, in contrast, function as flowering repressors in Brachypodium distachyon. FPL1 and FPL7 interact with the components of the florigen activation complex (FAC) and inhibit FAC activity to restrict expression of its critical target, VERNALIZATION1 (VRN1), in leaves, thereby preventing overaccumulation of FLOWERING LOCUS T1 (FT1) at the juvenile stage. Further, VRN1 can directly bind to the FPL1 promoter and repress FPL1 expression; hence, as VRN1 gradually accumulates during the late vegetative stage, FAC is released. This accurate feedback regulation of FPL1 by VRN1 allows proper FT1 expression in leaves and ensures sufficient FAC formation in shoot apical meristems to trigger timely flowering. Overall, we define a sophisticated modulatory loop for flowering initiation in a temperate grass, providing insights toward resolving the molecular basis underlying fine-tuning flowering time in plants.
开花促进因子 1（FPF1）是一种没有任何已知结构域的小蛋白，能促进几种植物开花；然而，其功能机制仍不清楚。在这里，我们鉴定了 2 个 FPF1 类似蛋白，FPL1 和 FPL7，它们在拟南芥中作为开花抑制子发挥作用。FPL1 和 FPL7 与成花激活复合物（FAC）的组成成分相互作用，并抑制 FAC 的活性，从而限制其关键靶标 VERNALIZATION1（VRN1）在叶片中的表达，从而防止在幼年阶段 FT1 的过度积累。此外，VRN1 可以直接结合 FPL1 启动子并抑制 FPL1 的表达；因此，随着 VRN1 在营养生长后期逐渐积累，FAC 被释放。VRN1 对 FPL1 的这种精确反馈调节允许 FT1 在叶片中进行适当表达，并确保在茎尖分生组织中形成足够的 FAC，以触发适时开花。总的来说，我们定义了一个精确的开花起始的调节环，为在温带禾本科植物中阐明开花时间的分子基础提供了新的思路。
