Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo, 113-0033 Japan.
Plant Cell Physiol. 2017 Nov 1;58(11):2017-2025. doi: 10.1093/pcp/pcx133.
In the facultative long-day plant Arabidopsis thaliana, FLOWERING LOCUS T (FT), encoding the mobile hormone florigen, plays an essential role in modulating the optimal timing of flowering to ensure reproductive success. Under inductive long-day conditions, the transcription of FT is activated by the CONSTANS (CO)/NUCLEAR FACTOR-Y (NF-Y) protein complex in leaf phloem companion cells. FT is transported to the shoot apical meristem through interaction with florigen transporters, such as SODIUM POTASSIUM ROOT DEFECTIVE 1 (NaKR1). Some regulators involved in photoperiod-dependent FT function have been reported previously; however, the molecular mechanism that coordinates FT protein synthesis and transport efficiently needs to be investigated. The present study examined the role of an Myb-related transcription factor, FE, in the activation of FT gene transcription and FT protein transport. Expression analysis using FE-inducible systems and chromatin immunoprecipitation assays showed that FE directly bound to the FT and NaKR1 promoters and activated the transcription of downstream target genes. FE failed to activate FT expression without CO function, whereas FE-mediated NaKR1 induction was not affected by CO function. Taken together, our data indicate that FE regulates the transcription of FT and florigen transporter genes via different mechanisms.
在兼性长日照植物拟南芥中，编码移动激素成花素的 FLOWERING LOCUS T（FT）在调节最佳开花时间以确保生殖成功方面起着至关重要的作用。在诱导的长日照条件下，FT 的转录被 CONSTANS（CO）/核因子-Y（NF-Y）蛋白复合物在叶韧皮部伴细胞中激活。FT 通过与成花素转运蛋白（如 SODIUM POTASSIUM ROOT DEFECTIVE 1（NaKR1））相互作用而被运送到茎顶端分生组织。先前已经报道了一些参与光周期依赖性 FT 功能的调节剂；然而，需要研究有效地协调 FT 蛋白合成和运输的分子机制。本研究检查了一个 Myb 相关转录因子 FE 在 FT 基因转录和 FT 蛋白运输激活中的作用。使用 FE 诱导系统和染色质免疫沉淀分析进行的表达分析表明，FE 直接结合到 FT 和 NaKR1 启动子上，并激活下游靶基因的转录。没有 CO 功能的情况下，FE 无法激活 FT 的表达，而 CO 功能对 FE 介导的 NaKR1 诱导没有影响。总之，我们的数据表明 FE 通过不同的机制调节 FT 和成花素转运蛋白基因的转录。
