Cytosine methylation is an epigenetic modification with essential roles in diverse plant biological processes including vegetative and reproductive development and responsiveness to environmental stimuli. A dynamic process involving DNA methyltransferases and DNA demethylases establishes cytosine DNA methylation levels and distribution along the genome. A DNA demethylase gene from barley (Hordeum vulgare), DEMETER (HvDME), the homologue of the Arabidopsis thaliana DME (AtDME), has been characterized previously and found to respond to drought conditions. Here, the promoter of the HvDME gene was analysed further by in silico and DNA methylation analysis. The effect of drought conditions on the DNA methylation status of HvDME was investigated at single-cytosine resolution using bisulfite sequencing. It was demonstrated that the HvDME promoter can be divided into two discrete regions, in terms of DNA methylation level and density; a relatively unmethylated region proximal to the translational start site that is depleted of non-CG (CHG, CHH) methylation and another distal region, approximately 1500 bp upstream of the translational start site, enriched in CG, as well as non-CG methylation. Drought stress provoked alterations in the methylation status of the HvDME promoter distal region, whereas the DNA methylation of the proximal region remained unaffected. Computational analysis of the HvDME promoter revealed the presence of several putative regulatory elements related to drought responsiveness, as well as transposable elements (TEs) that may affect DNA methylation. Overall, our results expand our investigations of the epigenetic regulation of the HvDME gene in response to drought stress in barley and may contribute to further understanding of the epigenetic mechanisms underlying abiotic stress responses in barley and other cereals.

胞嘧啶甲基化是一种表观遗传修饰，在多种植物生物过程中具有重要作用，包括营养和生殖发育以及对环境刺激的响应。涉及 DNA 甲基转移酶和 DNA 去甲基化酶的动态过程确定胞嘧啶 DNA 甲基化水平和沿基因组的分布。来自大麦 ( Hordeum vulgare )的 DNA 脱甲基酶基因DEMETER ( HvDME )，拟南芥 DME ( AtDME )的同源物，先前已被表征并发现对干旱条件有反应。在这里，通过计算机进一步分析了HvDME基因的启动子和 DNA 甲基化分析。使用亚硫酸氢盐测序以单胞嘧啶分辨率研究干旱条件对HvDME DNA 甲基化状态的影响。结果表明，就 DNA 甲基化水平和密度而言，HvDME启动子可以分为两个不连续的区域；靠近翻译起始位点的一个相对未甲基化的区域，该区域耗尽了非 CG (CHG, CHH) 甲基化和另一个远端区域，位于翻译起始位点上游约 1500 bp 处，富含 CG 和非 CG 甲基化。干旱胁迫引起HvDME甲基化状态的改变启动子远端区域，而近端区域的 DNA 甲基化不受影响。HvDME启动子的计算分析显示存在与干旱响应性相关的几种推定调控元件，以及可能影响 DNA 甲基化的转座元件 (TE)。总的来说，我们的结果扩展了我们对HvDME基因响应大麦干旱胁迫的表观遗传调控的研究，并可能有助于进一步了解大麦和其他谷物非生物胁迫反应的表观遗传机制。