VQ25调节拟南芥开花的分子机理研究

Flowering is a critical developmental stage in higher plants that may influence directly on biomass and crop yield. Six distinct regulatory pathways, including age, autonomous, gibberellin, photoperiod, vernalization, and ambient temperature pathways, have been assigned to control flowering time of plants in response to endogenous and exogenous cues in Arabidopsis thaliana. Genetic and molecular studies have identified many important genes involved in these pathways. FT is a central component that integrates multiple pathways and it moves from leave tissues to shoot apical meristem to initiate flowering. Among these pathways, the ambient temperature pathway is less well understood. PIF4 transcription factor is one of a few proteins that have been investigated in this pathway. PIF4 promotes the expression of FT in response to high temperature. In our previous study, we functionally characterized a plant-specific family, named VQ family, and found that loss-of-function mutant of VQ25 flowered early when grown at 30℃. Our data showed that high temperature induces VQ25 expression and that VQ25 can interact with PIF4 in yeast cells. These results indicate that VQ25 might be a novel factor in ambient temperature-mediated flowering pathway. In this study, we propose to elucidate the function and mechanism of VQ25 in regulating flowering time, including its gene expression, protein localization, relationship with PIF4, and regulation of FT. We believe that this study will add a novel component and gain new insight into the regulatory network of flowering time, and will provide a potential tool for molecular breeding of crops.

开花是高等植物的重要发育阶段，直接影响植物生物量和作物产量。植物感受体内和外界的信号，通过年龄、自主、赤霉素、光周期、春化和环境温度等途径控制开花时间，涉及大量的基因参与。FT 是其中最为核心的因子，整合了各条通路的信号，受激活后，FT蛋白从叶片移动到茎端分生组织，促进开花。环境温度调控的开花途径被发现较晚，至今只揭示了数个基因在其中发挥作用，其中PIF4响应高温，并促进FT表达。我们前期以拟南芥为材料，对植物特有的VQ基因家族进行了研究，发现其中的vq25突变体在30℃高温下提前开花，高温促进VQ25基因表达，并且VQ25可以与PIF4在酵母中相互作用，表明VQ25可能是环境温度调控开花的新因子。本项目将从VQ25的功能、基因表达、蛋白定位、与PIF4的关系、对FT等下游基因的调节等方面，对VQ25调控开花的分子机制进行深入阐释。研究成果有望阐明VQ25及PIF4促进开花的作用机理，拓展环境温度促进开花的遗传网络，为农作物花期控制的分子改良育种提供理论依据。

光是植物的一种重要的环境因子，调控包括种子萌发、形态建成、生物钟、开花和衰老等植物生长发育的各个过程。开花是高等植物从营养生长进入生殖生长的关键发育阶段，对环境（光照、温度）的变化非常敏感。开花时间对农作物生长和农业生产起着十分重要的作用。本项目关注几个关键因子在植物形态建成和开花过程响应环境变化中的功能和作用机制。VQ蛋白家族是近年来发现的植物特有的一类转录调控因子，本项目对该家族的其中一个成员VQ25蛋白的生物学功能和生化性质开展了深入研究，结果表明：VQ25是调控拟南芥开花的负向因子，其基因表达具有发育时期和组织特异性，受到环境高温诱导；VQ25与PIF4转录因子相互作用，干扰PIF4结合成花素基因FT启动子；同时，VQ25也能与FT互作。该研究揭示了VQ25 和PIF4 转录因子互作调控开花的分子机制。此外，研究揭示了CCA1-PKL组成的信号通路在响应高温信号中的新功能，为光照与温度信号在表观遗传水平的整合调控提供了新的见解。揭示了由PIF、HY5和BBX23组成的转录级联反应调控植物光形态建成的分子机制。揭示了由顺式元件介导的VAL1抑制FT的机制。