不同水陆环境中喜旱莲子草甲基化调控因子表达水平和差异表达基因启动子区甲基化状态分析

Differential Expression of DNA Methylation Regulating Factors and Dynamic Methylation Patterns of Alternanthera philoxeroides under Different Water Treatments

DNA甲基化是一种重要的表观遗传调控方式,参与对植物生长发育的调控,并在植物逆境胁迫响应中发挥作用。DNA甲基化的建立和维持是胞嘧啶甲基转移酶、染色质重塑酶、组蛋白修饰因子和去甲基化因子等协同作用的结果,环境胁迫能诱导植物体内DNA甲基化状态改变,进而改变基因表达水平和式样,影响植物的适应性。喜旱莲子草是一种恶性入侵植物,种内遗传多样性很低,主要依靠极强的表型可塑性侵占不同水陆生境。对克隆繁殖的喜旱莲子草个体进行不同时间的淹水处理,并用定量PCR方法检测16个DNA甲基化调控基因在不同处理条件下的表达水平和变化趋势,发现其中13个基因在不同处理时间点的表达水平有明显变化,且在淹水植株中多数基因在处理前期被强烈诱导上调表达。运用亚硫酸氢钠测序技术对两个在不同水陆条件下明显差异表达基因(Contig942和Contig23336)的上游启动子区甲基化动态进行分析,发现启动子区多个胞嘧啶位点的甲基化修饰状态在不同水陆条件下及淹水处理的不同时期呈现快速且可逆的动态变化,可能影响这些基因在不同环境条件下的表达水平。本研究结果能帮助了解喜旱莲子草表型可塑性变异和适应性发生的分子机理。

DNA methylation functions as an important epigenetic mechanism involved in various biological processes. Different enzymes participate in the dynamic regulation of DNA methylation status. Changes in DNA methylation can be induced by environmental factors and can result in phenotypic variations by altering gene expression and eventually ontogenetic trajectory. Alternanthera philoxeroides is an invasive species that grows in a variety of habitats, showing high phenotypic plasticity. To investigate the effects of epigenetic modulation on phenotypically variation of A. philoxeroides,the gene expression patterns of 16 DNA methylation regulating factors were measured at different time points of water treatment using quantitative RT-PCR. Thirteen genes responsible for DNA and histone methylation were differentially expressed under different water treatments,with most up-regulated in the early stages of water treatment. Bisulfite sequencing was employed to detect the methylation statusof CpG islands within the promoter regions of two genes,Contig942 and Contig23336,which were differentially expressed in response to different water treatments. Some cytosines,especially at asymmetric CHH sites,experienced fast and reversible changes in methylation status during water treatment. These changes in promoter methylation were probably responsible for the altered expression of these genes in different environments.