拟南芥蓝光受体CRY2调控向重性的分子机理研究

Blue light receptor Cryptochromes (CRYs) regulate photomorphogenesis,photoperiodic control of floral initiation and so on in plants,and circadian rhythms in several species. In the last two decades, significant progress has been made in the mechanisms of regulation of hypocotyl elongation and floral initiation, but many other functions of CRYs still remain to be studied further. Our previous results showed a constitutively activated mutant of CRY2,CRY2W374A, which overexpression transgenic lines presented a weakened gravitropism in darkness, while CRY2 interacting protein CIB1 overexpression transgenic plants also appeared similar phenotype in the dark, suggesting that CRY2 may regulate gravitropism through CIB1.To research the mechanism of gravitropism has appreciable impact on agricultural production. The exploration of Cryptochromes function in gravitropsm is constraint by phototropism and other photoreceptors. CRY2W374A, active without light, provide a good material for gravitropism research of Cryptochromes. In this project we will try to identify the target genes of Arabidopsis CRY2 in gravitropism response, and uncover the mechanism of CRY2 regulating gravitropism by using bioinformatics, molecular biology, genetics and biochemistry methods.

蓝光受体隐花素（CRY）调控了植物的光形态建成、开花等以及不同物种的生物钟。在过去二十年中对拟南芥隐花素调控下胚轴生长与开花时间的研究取得了一定进展，但对于隐花素其他功能及调控机理还亟待研究。我们在前期研究中发现了拟南芥CRY2一个组成型激活突变体CRY2W374A，其过表达转基因植株在黑暗下呈现向重性削弱表型，而CRY2相互作用蛋白CIB1过表达转基因植株在黑暗下也出现相似表型，暗示CRY2有可能通过CIB1介导了对向重性的调控。植物向重性的研究在农业生产中具有非常重要的意义。隐花素影响植物向重性的研究一直受到向光性与其它光受体的约束，CRY2W374A突变体在黑暗下保持活性为研究隐花素对向重性的影响提供了很好的材料。本项目拟在前期工作基础上采用生物信息学、分子生物学、遗传学和生物化学相结合的手段，寻找CRY2调控向重性的下游靶基因，并深入研究CRY2调控向重性的分子机理。

蓝光能够促进植物向光性生长，同时抑制植物的向重性（包括根的向地性与茎的背地性），已有文献证明隐花素CRY参与了该响应过程, 但也有人推测隐花素对向重性的抑制有可能是因为介导向光性所导致，隐花素影响植物向重性的研究一直受到向光性与其它光受体的约束。CRY2W374A突变体在黑暗下保持活性为研究隐花素对向重性的影响提供了很好的材料，有利于区分向光性与向重性，排除其他光受体的影响。我们的实验发现CRY2W374A突变体在黑暗呈现倒伏的表型，抑制了下胚轴的背地性但不影响根的向地性，且CRY2相互作用蛋白CIB1过表达转基因植株、PIFs突变体植株在黑暗下也出现相似表型，暗示CRY2有可能通过这些下游信号因子介导蓝光对下胚轴向重性的调控。通过qPCR检测发现向重性相关基因SGR5、GRV等在CRY2与CIB1过表达植株中显著降低。我们的研究结果暗示CRY2有可能通过不同转录因子（CIBs、PIFs）共同调控下游基因表达从而实现对向重性的调控，具体调控机制还将被深入研究。