光信号转录因子PIF调控植物低温应答的分子机制

Cold stress is a major environmental factor that adversely affects plant growth and development, and crop productivity. Light is a major environmental factor that controls plant growth and development. Our previous study uncovers an important role of PIF3 (phytochrome interacting factor3) in Arabidopsis freezing tolerance by negatively regulating the expression of genes in the CBF pathway. However, how light and temperature signals coordinately integrate to regulate PIF-mediated cold responses is poorly understood. In this proposal, we will investigate the exact role of PIF family proteins in cold signaling, and reveal the mechanism by which low temperature and light signaling coordinately mediates the modification and stability of PIFs. Furthermore, the regulatory function of the key light components in plant cold response will be explored in details. This study will allow us to dissect a novel molecular mechanism by which light and temperature balance plant growth and stress response, and provide new information for molecular breeding and crop improvement.

低温逆境严重影响植物的生长发育和作物产量，研究植物对低温的响应机制对提高植物耐冷性具有重要理论意义。光是植物必需的环境因子，在其生长发育过程中发挥关键作用。前期研究发现，光信号通路的关键转录因子PIF3 (phytochrome interacting factor3) 参与负调控植物的抗冻性。然而，植物如何整合光和温度信号来调节PIF介导的低温应答机制仍不清楚。本项目拟研究PIF家族蛋白在低温信号中的作用，以及光温信号协同调控PIF蛋白稳定性的分子机制，以期探究光信号关键组分在植物低温应答中的作用。该研究将有助于阐明光温信号在调控植物生长和逆境应答中的相互关系，为作物抗寒性育种提供基因资源和理论依据。

课题围绕“光信号转录因子PIF调控植物低温应答的分子机制”这一科学问题，通过细胞生物学、遗传学和生物化学等方法系统研究植物光信号与低温信号交互作用的生物学意义，发现低温下CBFs和PIF3存在直接的相互作用，这种互作抑制了PIF3和光敏色素phyB蛋白的共降解，揭示CBFs和PIF3相互作用整合低温信号和phyB介导的光信号，阐明了phyB在植物适应低温逆境过程中的重要作用；同时，CBF1能够和光敏色素phyA和phyB相互作用，促进PIF4/PIF5蛋白在光下的积累，表明CBF1在环境温度下通过调控phyB-PIF4/PIF5信号模块促进拟南芥下胚轴的伸长；揭示了拟南芥蓝光受体隐花色素CRY2与COP1-HY5模块通过不依赖于CBF/DREB1的BBX7/8转录因子正调控植物的抗冻性；全基因组结合位点分析构建了CBF调控植物低温应答、光信号和其他信号的分子调控网络；同时揭示转录因子bZIP68启动子自然变异调控玉米耐冷性的分子机制。