TCP4-dependent induction of CONSTANS transcription requires GIGANTEA in photoperiodic flowering in Arabidopsis.
TCP4-dependent induction of CONSTANS transcription requires GIGANTEA in photoperiodic flowering in Arabidopsis.
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DOI：
10.1371/journal.pgen.1006856
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发表时间：
2017-06
期刊：
影响因子：
4.5
通讯作者：
Imaizumi T
中科院分区：
文献类型：
--
作者：
Kubota A;Ito S;Shim JS;Johnson RS;Song YH;Breton G;Goralogia GS;Kwon MS;Laboy Cintrón D;Koyama T;Ohme-Takagi M;Pruneda-Paz JL;Kay SA;MacCoss MJ;Imaizumi T
光周期是植物调节开花时间最可靠的环境信号之一。在拟南芥中，CONSTANS（CO）转录因子在光周期开花调控中起着重要作用。相对于CO蛋白的翻译后调控，CO的转录调控仍然知之甚少。在这里，我们表明，肉桂（CIN）进化枝的第二类TEOSINTE分支1/环类/增殖细胞核抗原因子（TCP）蛋白作为CO激活剂。我们的酵母单杂交分析表明，II类CIN-TCP，包括TCP 4，结合到CO启动子。TCP 4通过在体内直接与CO启动子结合在黄昏前后诱导CO表达。此外，TCP 4在细胞核中与另一种开花调节因子GIGANTEA（GI）结合，并以GI依赖性方式诱导CO表达。在gi突变体中，TCP 4与CO启动子的物理结合减少，表明GI可能增强TCP 4的DNA结合能力。我们的串联亲和纯化结合质谱（TAP-MS）分析确定了所有II类CIN-TCP作为体内TCP 4复合物的组分，并且gi突变体没有改变TCP 4复合物的组成。综上所述，我们的研究结果表明，CIN-TCPs作为光周期开花调节剂，这可能有助于协调植物发育与开花调节的新功能。对于植物适应季节性环境，一个关键的发育事件是开花，因为开花的适当时机影响生殖成功。虽然植物监测各种环境参数，以优化这一时间，光周期信息是重要的植物调节季节性开花时间，因为光周期的变化发生在一年四季的可预测的方式。模式植物拟南芥对光周期变化和长日照条件下开花的反应。基于使用光周期开花反应缺陷突变体的遗传分析，我们了解到称为CONSTANS（CO）的转录因子通过直接控制成花素（开花诱导底物）基因的表达在调节开花时间方面起着核心作用。长日下午表达的CO是至关重要的，这种调节，但是，我们有限的知识CO转录调控。在这里，我们确定了一组属于TCP基因家族的植物特异性转录因子作为新的CO转录激活因子。我们表明，TCP转录因子调节CO转录与已知的CO调节。我们的研究结果表明，植物利用多种转录因子精确协调关键调控基因，CO，这将直接影响开花时间的表达。
Photoperiod is one of the most reliable environmental cues for plants to regulate flowering timing. In Arabidopsis thaliana, CONSTANS (CO) transcription factor plays a central role in regulating photoperiodic flowering. In contrast to posttranslational regulation of CO protein, still little was known about CO transcriptional regulation. Here we show that the CINCINNATA (CIN) clade of class II TEOSINTE BRANCHED 1/ CYCLOIDEA/ PROLIFERATING CELL NUCLEAR ANTIGEN FACTOR (TCP) proteins act as CO activators. Our yeast one-hybrid analysis revealed that class II CIN-TCPs, including TCP4, bind to the CO promoter. TCP4 induces CO expression around dusk by directly associating with the CO promoter in vivo. In addition, TCP4 binds to another flowering regulator, GIGANTEA (GI), in the nucleus, and induces CO expression in a GI-dependent manner. The physical association of TCP4 with the CO promoter was reduced in the gi mutant, suggesting that GI may enhance the DNA-binding ability of TCP4. Our tandem affinity purification coupled with mass spectrometry (TAP-MS) analysis identified all class II CIN-TCPs as the components of the in vivo TCP4 complex, and the gi mutant did not alter the composition of the TCP4 complex. Taken together, our results demonstrate a novel function of CIN-TCPs as photoperiodic flowering regulators, which may contribute to coordinating plant development with flowering regulation. For plant adaptation to seasonal environments, a crucial developmental event is flowering, as proper timing of flowering affects reproductive success. Although plants monitor various environmental parameters to optimize this timing, photoperiod information is important for plants to regulate seasonal flowering time, because changes in photoperiod occur in a predictable manner throughout the year. The model plant Arabidopsis thaliana responds to photoperiodic changes and flowers under long-day conditions. Based on genetic analyses using mutants defective in the photoperiodic flowering response, we learned that the transcription factor referred to as CONSTANS (CO) plays a central role in regulating the timing of flowering by directly controlling the expression of florigen (flowering-inducing substrate) gene. Long-day afternoon expression of CO is critical for this regulation; however, we had limited knowledge of CO transcriptional regulation. Here we identified that a group of plant-specific transcription factors belonging to the TCP gene family function as novel CO transcriptional activators. We demonstrated that TCP transcription factors regulate CO transcription together with known regulators of CO. Our results imply that plants utilize multiple transcription factors to precisely coordinate the expression of the key regulator gene, CO, which will directly affect flowering time.