所有生物都进化出精细的DNA损伤修复系统以维持基因组的稳定性。蛋白质翻译后修饰（如磷酸化、泛素化）在DNA损伤修复过程中发挥了极其重要的作用。在动物中，E3泛素连接酶RNF8和RNF168对修复DNA双链断裂是必需的。但是在植物中还没有发现RNF8和RNF168的同源蛋白或类似功能蛋白。因此，植物修复DNA双链断裂的机理有待进一步解析。拟南芥有一个含BRCT和RING结构域的E3泛素连接酶CSM1，其生物学功能尚不清楚。在前期的研究中，我们发现csm1突变体对DNA双链断裂试剂极度敏感。我们推测CSM1具有类似RNF8或RNF168的功能。本项目将鉴定CSM1泛素化的底物，解析CSM1调控DNA损伤修复的分子机理。本项目的开展不仅有助于发现植物调控DNA双链断裂修复的新基因(CSM1)，而且有助于揭示植物调控DNA损伤修复的新机制(泛素化修饰)，具有重要的科学意义。

All organisms evolved with sophisticated DNA damage repair system to maintain genome stability. Posttranslational modifications (such as phosphorylation and ubiquitination) play crucial roles in DNA damage repair. In animals, two E3 ubiquitin ligases RNF8 and RNF168 are required to repair double strand breaks (DSB). However, the homologs of RNF8 and RNF168 or their functional counterparts were not identified in the plants yet. Therefore, the mechanisms of DSB repair in plants need to be further elucidated. Arabidopsis contains an E3 ubiquitin ligase with BRCT and RING motifs, and its biological functions are still unknown. In previous studies, we found that the csm1 mutant was hypersensitive to DSB reagents. We hypothesize that CSM1 has similar functions to RNF8 or RNF168. In this project, we are aiming to identify CSM1 targets and reveal the mechanisms of CSM1 in regulating DNA damage repair. This study will not only help to discover CSM1 as a novel gene in regulating DSB repair, but also help to reveal ubiquitination modification as a new mechanism of DNA damage repair in plants, which is of great scientific significance.