拟南芥FBP基因调控植物开花启始的分子机制研究

The initiation of flowering is regulated by both genetic factors and environmental signals. Accurate flowering time can increase crop seed setting rate, thus increase agricultural yield. FLC is the major flowering repressor in Arabidopsis thaliana, which integrates many flowering signaling pathways. The FPA protein in the autonomous pathway regulates the expression of FLC by mediating mRNA 3’ end formation. In this study, we have gained FBP (FPA Binding Protein) through Y2H screening. It is showed that the fbp mutant displayed the late flowering phenotype under both long day and short day condition, and the expression of FLC was increased in fbp. Furthermore, it is also showed that FBP, like FPA, plays an important role in mRNA 3’ end formation. These results suggest that FBP may be involved in the regulation of FLC expression together with FPA, thus regulates the initiation of flowering. In order to analysis the function of FBP in flowering initiation, we plan to do the experiments including protein interaction validation (such as Pull-Down, Co-immunoprecipitation), homozygous transgenic lines construction, genetic hybridization, RNA 3 'polyadenylation site detection, FBP interaction protein screening and function analysis. This study will help us to understand the molecular mechanism of FBP in flowering signaling. Outcomes of this project will not only shed new light on the function of FBP in flowering initiation, but also provide novel theoretical bases in order to develop innovative strategies to control the process of flowering in agricultural and horticultural crops for desired traits.

植物开花启始受到自身遗传因子和外界环境因素的共同影响。精确的开花时间能够增加作物结实率，对农业生产至关重要。FLC是植物开花启始的重要开关，它整合了多条开花信号途径。自主途径中的FPA蛋白通过介导RNA的3’端多聚腺苷化位点的选择从而调控FLC的表达。本项目在前期研究中获得与FPA互作的蛋白FBP（FPA Binding Protein），研究发现，FBP和FPA形成复合体，在RNA的3’端多聚腺苷化位点的选择中起重要作用，从而调控FLC的表达，调控植物开花的启始。在此基础上拟通过蛋白互作验证（如Pull-Down、免疫共沉淀等）、转基因纯合株系的构建、遗传杂交、RNA的3’端多聚腺苷化位点检测、FBP互作靶基因的筛选及具体功能研究等方法系统研究FBP调控开花启始的功能，以期阐明FBP调控开花启始的具体分子机制，为作物育种提供新的理论依据和分子靶标。

植物开花启始受到自身遗传因子和外界环境因素的共同影响。精确的开花时间能够增加作物结实率，对农业生产至关重要。FLC是植物开花启始的重要开关，它整合了多条开花信号途径。自主途径中的FPA蛋白通过介导RNA的3’端多聚腺苷化位点的选择从而调控FLC的表达。但FPA如何选择多聚腺苷化位点，从而调控FLC基因的表达，还需进一步深入研究。本项目围绕解析和FPA蛋白互作的蛋白FBP（FPA Binding Protein）调控植物开花的分子机制展开研究。首先，我们通过酵母双杂交、Pull down和免疫共沉淀等方法验证FBP与FPA的互作，并且发现fbp突变体在长光照和短光照条件下开花时间都晚于野生型（WT），且fpa-7 fbp双突变体的开花时间明显晚于各自的单突变体fbp或者fpa-7突变体。随后我们对FBP调控植物开花的机制做进一步研究。研究结果表明，FBP通过调控FLC基因的表达，从而调控植物开花。且发现FBP和FPA一样，可以防止远端多聚腺苷酸化COOLAIR转录物和FLC的过度表达。进一步研究发现FPA在FLC基因组位点的结合依赖于FBP的活性。在此基础上，我们进一步通过酵母双杂交筛选得到FBP的互作蛋白FBPIP（FBP INTERACTING PROTEIN），初步研究结果显示FBPIP也具有调控开花启始的重要功能。fbpip突变体在长日照和短日照条件下均呈现晚花表型，且fbpip突变体中FLC基因表达量上升，FT、SOC1基因表达量下降。进一步研究发现，FBPIP和FBP、FPA一样，在COOLAIR的多聚腺苷酸化位点的选择中起重要作用。这些结果不仅阐明了FBP蛋白调控植物开花的分子机制，而且为进一步挖掘调控植物开花的重要基因奠定了基础。