A Molecular Switch for FLOWERING LOCUS C Activation Determines Flowering Time in Arabidopsis

背景回顾：Plants have evolved sophisticated mechanisms to ensure flowering in favourable conditions for reproductive success. In the model plant Arabidopsis thaliana, FLOWERING LOCUS C (FLC) acts as a central repressor of flowering and the major determinant for winter cold requirement for flowering. FLC is activated in winter annuals by the FRIGIDA (FRI) activator complex containing FRI, FLC EXPRESSOR (FLX) and FLX-LIKE 4 (FLX4), among which FLXand FLX4 are also essential for establishing basal FLC expression in summer annuals. 

主要发现：Here we show that a plant RNA polymerase II C-terminal domain phosphatase, C-TERMINAL DOMAIN PHOSPHATASE-LIKE 3 (CPL3), interacts with and dephosphorylates FLX4 through their scaffold protein FLX to inhibit flowering. 

分子机制：CPL3-mediated dephosphorylation of FLX4 serves as a key molecular switch that enables binding of dephosphorylated FLX4 to the FLC locus to promote FLC expression, thus repressing flowering in both winter and summer annuals of Arabidopsis. 

结论：Our findings reveal a molecular switch underlying the activation of FLC for flowering time control.

 摘 要 

植物已经演化出比较复杂的机制，用以在最佳环境条件下开花，以保证繁殖的成功。在模式植物拟南芥中，FLC是核心的开花抑制因子，也是植物需要冬季低温以确保开花的主要决定因子。在冬季一年生植物中，FLC会被包含FRI、FLX以及FLX4所构成的FRI激活复合物所激活，其中FLX和FLX4同时也是夏季一年生植物中建立基础FLC表达所必需的。本文中，作者发现了一种植物RNA聚合酶II C端结构域磷酸酶CPL3，其通过本身的支架蛋白FLX与FLX4相互作用，并去磷酸化FLX4，以抑制开花。CPL3介导的FLX4去磷酸化是一个关键的分子开关，去磷酸化的FLX4能够结合到FLC位点，促进FLC的表达，从而抑制冬季和夏季一年生拟南芥属植物的开花。本文的研究结果揭示了一种激活FLC以控制开花时间的分子开关。

 通讯作者 

** Lisha Shen **