Institute of Applied Biosciences (INAB), CERTH, Thermi-Thessaloniki GR-57001, Greece.
BMC Plant Biol. 2013 Oct 31;13:172. doi: 10.1186/1471-2229-13-172.
Epigenetic factors such as DNA methylation and histone modifications regulate a wide range of processes in plant development. Cytosine methylation and demethylation exist in a dynamic balance and have been associated with gene silencing or activation, respectively. In Arabidopsis, cytosine demethylation is achieved by specific DNA glycosylases, including AtDME (DEMETER) and AtROS1 (REPRESSOR OF SILENCING1), which have been shown to play important roles in seed development. Nevertheless, studies on monocot DNA glycosylases are limited. Here we present the study of a DME homologue from barley (HvDME), an agronomically important cereal crop, during seed development and in response to conditions of drought.
An HvDME gene, identified in GenBank, was found to encode a protein with all the characteristic modules of DME-family DNA glycosylase proteins. Phylogenetic analysis revealed a high degree of homology to other monocot DME glycosylases, and sequence divergence from the ROS1, DML2 and DML3 orthologues. The HvDME gene contains the 5' and 3' Long Terminal Repeats (LTR) of a Copia retrotransposon element within the 3' downstream region. HvDME transcripts were shown to be present both in vegetative and reproductive tissues and accumulated differentially in different seed developmental stages and in two different cultivars with varying seed size. Additionally, remarkable induction of HvDME was evidenced in response to drought treatment in a drought-tolerant barley cultivar. Moreover, variable degrees of DNA methylation in specific regions of the HvDME promoter and gene body were detected in two different cultivars.
A gene encoding a DNA glycosylase closely related to cereal DME glycosylases was characterized in barley. Expression analysis during seed development and under dehydration conditions suggested a role for HvDME in endosperm development, seed maturation, and in response to drought. Furthermore, differential DNA methylation patterns within the gene in two different cultivars suggested epigenetic regulation of HvDME. The study of a barley DME gene will contribute to our understanding of epigenetic mechanisms operating during seed development and stress response in agronomically important cereal crops.
表观遗传因子，如 DNA 甲基化和组蛋白修饰，调节植物发育的广泛过程。胞嘧啶甲基化和去甲基化处于动态平衡中，分别与基因沉默或激活相关。在拟南芥中，胞嘧啶去甲基化是由特定的 DNA 糖苷酶实现的，包括 AtDME（DEMETER）和 AtROS1（REPRESSOR OF SILENCING1），它们已被证明在种子发育中发挥重要作用。然而，单子叶植物 DNA 糖苷酶的研究有限。在这里，我们研究了大麦（HvDME）中的一个 DME 同源物，大麦是一种重要的农业作物，在种子发育过程中以及在干旱条件下的表现。
在 GenBank 中鉴定出的 HvDME 基因被发现编码一种具有 DME 家族 DNA 糖苷酶蛋白所有特征模块的蛋白质。系统发育分析显示与其他单子叶 DME 糖苷酶高度同源，与 ROS1、DML2 和 DML3 同源物序列分化。HvDME 基因包含 3'下游区域内 Copia 反转录转座子元件的 5'和 3'长末端重复（LTR）。在营养组织和生殖组织中均检测到 HvDME 转录本，在不同的种子发育阶段和两个种子大小不同的不同品种中积累情况不同。此外，在耐旱大麦品种中，干旱处理显著诱导 HvDME 的表达。此外，在两个不同品种中，在 HvDME 启动子和基因体的特定区域检测到可变程度的 DNA 甲基化。
在大麦中鉴定出一个与谷物 DME 糖苷酶密切相关的编码 DNA 糖苷酶的基因。在种子发育和脱水条件下的表达分析表明，HvDME 在胚乳发育、种子成熟和应对干旱方面发挥作用。此外，在两个不同品种中，基因内的 DNA 甲基化模式差异表明 HvDME 的表观遗传调控。对大麦 DME 基因的研究将有助于我们理解在农业重要谷物的种子发育和应激反应中起作用的表观遗传机制。
