细胞周期调控机理是当今生物学研究的热点之一，和动物不同，植物能够持续地发育形成器官取决于其对细胞增殖的严格调控。本课题从植物特异的一类DOF转录因子入手发现OBP4/DOF5.4基因调控细胞周期和细胞扩张的作用。利用同步化的拟南芥MM2d悬浮细胞来研究OBP4基因细胞周期依赖的表达模式以悬浮细胞诱导表达OBP4对细胞周期进程的影响。构建组成型和诱导型启动子过表达，沉默表达转基因植株来研究改变OBP4表达水平对植物生长发育的影响，流式细胞仪检测植株细胞周期进程以及细胞内复制水平。OBP4作为一个核定位的转录因子可以通过转录调控下游靶基因来发挥功能，Affy芯片表达分析结合体外EMSA和体内CHIP实验鉴定其靶基因。保守DOF结构域可以介导蛋白互作，验证OBP4与可能的细胞周期调控相关的TCP, MYB蛋白互作及对下游靶基因结合力的影响。该研究丰富人们对于转录水平上调控植物细胞周期的认识。

The mechanism of cell cycle regulation is one of the hottest topics in the current biology. Unlike animals, plant development displays continuous organ formation and depends on strict regulation of cell proliferation. Here we report a plant specific DOF transcription factor OBP4 that controls cell proliferation and cell expansion. Use the synchronized MM2d Arabidopsis suspension cell to study OBP4 expression patterns and analyze its influence on cell cycle progression. Further, generate transgenic plants by constitutive/inducible overexpressing, down-regulation of OBP4 and analyze the effects of altered OBP4 expression levels to plant growth and development. Use flow cytometry method to detect the cell cycle progression and endocycle level. The nuclear protein OBP4 functions through the transcriptional regulation of downstream genes，Affy data are obtained together with the EMSA, CHIP assays to identify the direct target genes. The conserved DOF domain also mediates protein-protein interaction. We verify the likely interaction between DOF and the TCP, MYB family cell cycle regulators and evaluate the influence of OBP4 bind to its target genes. These findings will increase our understanding of transcriptional regulation of cell cycle in plants.