拟南芥成花素基因FT转录调控的组织细胞特异性机制

Flowering time plays an important role in environmental adaption and crop yield. FLOWERING LOCUS T is a key flowering-time gene. FT expresses in the phloem companion cells of leaves and its protein moves up to shoot apical meristem to induce floral transition. While FT expresses in the fruit phloem, it controls inflorescence stabilization and fruit development. In Abrabidopsis, transcriptional level of FT is regulated by many protein factors involving in photoperiod, temperature, hormone and ageing pathways as well as epigenetic regualtion. Recently, we found that the chromatin conformation structure between FT core promoter and its upstream enhancer played an important role in determining FT expression. To further dissect the internal and external factors controlling FT tissue-specific expression, we are planning to isolate phloem and epidemal cells from leaves and fruits by INTACT. In reponse to photoperiod and temperature change, the interaction among trans-factors, cis-elements and epigenetic regulation factors will be analyzed in those isolated cells. Our study not only helps to understand the tempo-spacial expression pattern of FT, but also contributes to regulating flowering time and improving crop yield through specifically inducing FT expression.

开花时间是影响植物环境适应性和作物产量的重要性状，成花素基因FT是开花时间调控的关键基因。FT在叶片韧皮部伴胞表达，其蛋白运输至茎尖生长点诱导开花；在角果韧皮部表达，则与花序原基稳定和果实发育相关。拟南芥FT基因转录受光照、温度、激素、年龄等多条开花途径及表观遗传调控因子的控制。我们近期的研究发现，FT核心启动子元件和上游增强子之间的染色质空间结构是FT基因表达的另一关键因素。为了进一步探讨影响FT组织特异性表达的内外因素，本研究拟采用INTACT技术分离叶片和角果中的韧皮部和表皮等特异性细胞核，重点分析光周期和温度影响下，FT表达所需的关键转录因子、顺式作用元件和表观遗传调控因子三者之间的相互作用，综合解析FT时空和组织细胞特异性表达的调控机制，从而为特异性诱导FT表达、调控开花时间和提高作物产量奠定理论基础。

开花时间是植物从营养生长向生殖生长过渡的关键发育调控点，对于植物繁衍后代、提高环境适应性至关重要，本项目旨在通过研究关键开花基因的表达调控机制为精准调控花期打下理论基础。首先我们聚焦到成花素基因FT的时空组织特异性表达机制，鉴定了控制其在叶片维管韧皮部表达的两个增强子元件，以及控制角果FT特异表达的新顺式作用元件。然后，通过INTACT-ATAC-seq分析鉴定了叶片维管和表皮中特异染色质开放区，挖掘了一些潜在的控制开花发育的新基因，并对其中的两个基因进行了功能验证。其次，我们发现了控制FT在一天中早晨表达调控的新基因属于核膜孔蛋白复合体成员，并解析了作用于CO蛋白稳定性的调控新机制。最后，我们选取不依赖春化作用的早花生态型拟南芥，其FT的上调表达是由于FLC基因中插入了转座子元件并介导了FLC的选择性转录起始所致。上述研究主要集中研究了开花遗传途径上的FT、CO和FLC几个关键开花因子，本项目支持的研究结果将在表观遗传、转录及转录后不同的水平，为成花素FT的时空组织特异性表达、及其上游转录因子的表达调控机制提供新的见解，为作物的花期遗传改良提供一定的理论基础。