拟南芥ROS1介导的DNA去甲基化作用具有拮抗DNA过度/不合理甲基化和激活转录基因沉默等功能，然而目前对ROS1作用机理以及所需蛋白因子的认识仍非常有限。本研究中，我们通过遗传筛选方法鉴定到一个新的与ROS1去甲基化相关的蛋白CRWN3。CRWN3突变造成基因组898个区域发生DNA超甲基化，与ros1-4相比共有361个超甲基化区域相重合；CRWN3和ROS1在体内有直接蛋白相互作用。相关研究表明，CRWN3和CRWN1在控制细胞核形态和植株发育方面有明显的功能冗余；CRWN蛋白家族具有在种子形成时阻止染色质过度压缩和种子萌发时促进染色质快速解压缩等功能。因此，CRWN3很可能通过促进种子萌发时染色质的充分解压缩而为ROS1去甲基化提供合适的染色质环境。本研究将进一步通过Co-IP、ChIP和FISH等技术，深入探索和研究CRWN3参与ROS1介导的DNA去甲基化过程的分子机理。

In Arabidopsis, ROS1-mediated DNA demethylation process plays important roles in pruning improper DNA methylation and activating transcriptional gene silencing. However, the current knowledge of how ROS1 works and what proteins are involved in the process remains poorly understood. In this study, by genetic screening we identified a new protein referred to as CRWN3 which is functionally associated with ROS1. Mutation of CRWN3 generates 898 hyper DMRs at the genome-wide level, in which 361 hyper DMRs are overlapped with those of ros1-4. CRWN3 physically interacts with ROS1 in vivo. A few studies revealed that CRWN3 and CRWN1 are to some extent functionally redundant in controlling nuclear shape and plant development. CRWNs generally prevent chromatin from overcondensation during seed maturation and promote rapid decondensation of the highly compacted chromatin during seed germination. So we speculate that during seed germination CRWN3 presumably promotes chromatin decondensation to create a favorable chromatin environment to facilitate ROS1 binding and functioning on target loci. To test this hypothesis, we are going to perform a series of experiments, such as Co-IP, ChIP and FISH, to elucidate the molecular mechanisms of how CRWN3 is involved in ROS1-mediated DNA demethylation process.