拟南芥CRF基因调控开花启始的功能研究

The floral transition of plants is regulated by their genetic factors and external enviromental signals. Accurate flowering time can increase crop seed setting rate, thus increase crop yield, and plays an important role in agricultural production. The Arabidopsis blue light receptor Cryptochrome (CRY) mediates photoperiodic control of floral initiation. Our previous studies found two Cryptochrome Regulated Factors, CRF1 and CRF2, the loss of function mutants crf1 and crf2 showed late flowering phenotype in Long day condition compared to wild type, but not in short day. The crf1crf2 double mutant flowered later than the single mutants. Our results indicated CRF may be involved in photoperiodic floral initiation regulation. Furthermore, the CRF1 protein was accumulated after blue light irradiation, the mRNA level of CRF1 was decreased under blue light.These specific blue light responses indicate that CRF may be the important components of blue light signal transduction. In this project we will try to systematicly investigate the flowering regulation function of CRF, and uncover the mechanism of CRF controlling flowering initiation by using molecular biology, genetics and biochemistry methods. It will reveal a novel perspective to the mechanism of flowering regulation.

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。拟南芥蓝光受体隐花素CRY对光周期依赖的开花启始起着重要的调控作用。本项目在前期研究中发现了受CRY调控的一类基因CRF基因（Cryptochrome Regulated Factor），具有调控开花启始的重要功能，crf1、crf2缺失突变体在长日照条件下呈现晚花表型，但不影响短日照条件下的开花时间，crf1crf2双突变体能加强单突变体在长日照下的晚花表型，说明CRF有可能参与了依赖光周期的开花调控途径。此外，CRF1转录水平受到蓝光抑制，蛋白被蓝光特异性稳定，说明CRF有可能是蓝光信号转导中的关键基因，介导蓝光调控开花启始。在此基础上拟采用分子遗传、生化等方法系统研究CRF调控开花时间的功能，以期阐明CRF调控开花的具体分子机制，为开花调控网络提供新的理论依据。

光和环境温度是影响植物生长发育最显著的两种非生物信号，都调控了植物生长、开花、生物节律、抗逆等一系列重要生物学过程。植物通过光受体响应环境中的光信号，且光受体参与温度响应过程。蓝光受体CRY1可以通过与温度响应关键分子PIF4直接相互作用参与温度信号的调控，同时隐花素还可以通过调控温度响应基因COR27/COR28的表达参与温度响应。我们发现COR27 (COLD REGULATED GENE 27) 和COR28 (COLD REGULATED GENE 28) 的转录水平被蓝光和温度共同调控。cor27 cor28在长日照条件下具有明显的晚花表型以及更好的抗冷冻胁迫能力。多条开花途径的关键基因表达受到影响，进一步研究发现它们有可能通过调控生物钟基因PRR5、TOC1的表达从而平衡植物的发育与抗逆过程。同时，蓝光稳定COR27和COR28蛋白水平，我们通过酵母双杂交获得了COR27、COR28相互作用的蛋白，获得了E3泛素连接酶COP1。我们发现COR27和COR28通过结合、bZIP类转录因子HY5而调控众多光形态建成下游基因表达。COR27和COR28在黑暗中被COP1降解，光信号通过抑制COP1而促进HY5和COR27的积累，同时COR27与HY5直接结合，抑制其转录活性，在黑暗中微调暗形态建成，在光照下调控光形态建成。