基因组稳定性的维持对植物的正常发育和遗传具有重要意义，但内在或外源因素都可能引起植物细胞的DNA损伤。表观遗传机制在染色质的结构和功能调控方面发挥关键作用，然而关于组蛋白修饰与DNA损伤修复联系的研究还不深入。SUMO化是一种重要的蛋白质翻译后修饰，参与植物生长发育和胁迫应答等重要过程，但是植物组蛋白SUMO化修饰直接参与DNA损伤应答的机理还未见报道。申请人通过系统性筛选首次发现拟南芥的组蛋白变体H2AX受到SUMO化修饰。由于H2AX是DNA损伤应答的关键因子，其SUMO化可能通过调控染色质结构影响下游基因表达或直接影响自身磷酸化状态参与损伤应答。因此，本项目拟通过生物化学、细胞生物学、遗传学和生物信息学等方法，研究组蛋白H2AX的SUMO化在植物DNA损伤应答中的分子功能和调控机制。本项目的开展将有利于拓宽我们对组蛋白修饰参与DNA损伤应答机制的理解，为农作物的生产改良提供理论依据。

Maintenance of genome stability is critical in plant development and reproduction, but DNA damage is always induced by endogenous and exogenous factors. The structure and function of chromatin is regulated by multiple epigenetic mechanisms, including histone modifications. However, the functional association between histone modifications and DNA repair remains unclear. SUMOylation is an important type of protein modification, which plays roles in regulation of plant development and stress responses, but the function of histone SUMOyaltion in plant DNA damage response has not yet been reported. First time, the applicant discovered that members of the Arabidopsis histone variant H2AX family are SUMOylated. Because H2AX is involved in the DNA damage signaling, SUMOylation may regulate this process via changing chromatin structures to control gene expression or directly affecting the phosphorylation status of H2AX at DNA damaging sites. In this project, the molecular function and regulation mechanism of H2AX SUMOylation in plant DNA damage response will be investigated via approaches from biochemistry, cell biology, genetics and bioinformatics. This study will improve our understanding on the functional association between histone modification and DNA damage response, and will be interesting for researchers in the field of agriculture.