植物DNA从头甲基化的机制  

Mechanism of de novo DNA methylation in plants

作　　者：胡港 徐强[1] Gang Hu;Qiang Xu(Key Laboratory of Horticultural Plant Biology of Ministry of Education,Huazhong Agricultural University,Wuhan 430070,China)

机构地区：[1]华中农业大学园艺林学学院,园艺植物生物学教育部重点实验室,武汉430070

出　　处：《科学通报》2021年第15期1821-1834,共14页Chinese Science Bulletin

基　　金：国家杰出青年科学基金(31925034);国家重点研发计划(2018YFD1000100);中央高校基本科研业务费专项基金资助。

摘　　要：DNA甲基化是一种常见的表观遗传修饰,与基因的表达调控、转座子的沉默及异染色质的形成等紧密相关.DNA从头甲基化是指在新位点建立甲基化修饰的过程.植物中存在多个DNA从头甲基化通路,主要分为RNA介导的DNA甲基化(RNA-directed DNA methylation,Rd DM)及CMTs(CHROMOMETHYLASEs)参与的从头甲基化.Rd DM通路在非编码RNA的介导下靶向建立甲基化修饰,可调控植物多类生长发育过程.伴随着研究的深入,多条非经典的Rd DM通路得以发现,这些通路在转座子的识别和沉默方面有着重要作用.此外,非模式植物中的研究还对CMT3参与从头甲基化的机理进行了探索.基于DNA从头甲基化机制,最近的研究开发了多种靶向DNA甲基化操控工具,这些工具将推进对DNA甲基化功能的认识,并有望进一步用于遗传操控进行作物改良.本文综述了植物DNA从头甲基化机制的最新研究进展,并针对该机制的应用进行了讨论.DNA methylation is a common epigenetic modification related to gene expression regulation,transposable element(TE)silencing and heterochromatin formation.The establishment of DNA methylation on unmethylated sites,which is termed as de novo DNA methylation,can trigger other epigenetic modifications to collectively maintain the genome stability and regulate gene expression.In plants,de novo DNA methylation is mediated by multiple pathways.Recent discoveries have uncovered more details regarding the mechanisms of these pathways and shown potential for application.Here,we summarize the latest advances in the studies of the mechanisms of de novo DNA methylation in plants,including canonical RNA-directed DNA methylation(RdDM),noncanonical RdDM and CHROMOMETHYLASEs(CMTs)related de novo DNA methylation.Canonical RdDM is a conserved pathway which mainly recruits DOMAINS REARRANGED METHYL ASE 2(DRM2),a de novo methyltransferase,to the targeted regions by two kinds of non-coding RNAs(nc RNAs):Heterochromatic small interfering RNAs(hetsi RNAs)and long non-coding RNAs.These nc RNAs are transcribed by two plant-specific RNA polymerase,Pol IV and Pol V,respectively.Noncanonical RdDM is specified because more small RNAs other than hetsi RNAs have been found to participate in RdDM.Although the major function of canonical RdDM is to maintain the silencing state of TEs,it is also important for many plant developmental processes,such as reproduction and fruit development.Noncanonical RdDM,on the other hand,plays a crucial role in the initiation of TE silencing.This pathway acts as a genome surveillance mechanism and triggers DNA methylation to re-silence transcriptionally active TEs.CMTs are methyltransferases that can directly bind methylated histone H3 Lys9(H3K9)and then mediate maintenance DNA methylation.Researches on non-model plants have suggested that CMTs can also function as de novo methyltransferase,and likely contribute to the gene body DNA methylation during plant evolution.Both RdDM and CMTs are involved in transcriptio

关 键 词：DNA甲基化 DNA从头甲基化 靶向DNA甲基化 植物 

分 类 号：Q943.2[生物学—植物学]