DNA methylation is known to regulate gene expression when plants are exposed to abiotic stress such as drought. Therefore, insight into DNA methylation pattern would be useful for a better understanding of the expression profile of genes associated with drought adaptation. In the present study, we attempted to analyse the DNA methylation pattern at the whole-genome level and the expression of a few drought-responsive genes in rice under different regimes of soil water status, i.e. puddled, 100 and 60% field capacities (FC). The methylation-sensitive randomly amplified polymorphic DNA analysis was employed to identify DNA methylation pattern. We observed an increase in DNA methylation at 60% FC, and reduced methylation under 100% FC compared to puddled condition. The genes such as protein phosphatases (PP2C) and phenylalanine ammonia-lyase (PAL) having CpG islands in their promoter region had lower expression level under 100 and 60% FC compared to puddled conditions. Heat shock protein 70 (HSP70) and RNA helicase 25 (RH25), with no CpG islands in their promoter region, exhibited enhanced expression compared to puddled plants. In rice, increased DNA methylation seems to be an important mechanism associated with drought responses, which probably regulates the methylation-sensitive gene expression. The drought-induced changes in DNA methylation would contribute for epigenetic mechanism. The study provided evidence to argue that drought-induced increased methylation might be one of the major mechanisms associated with acclimation responses in field crops like rice.

中文翻译：

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利用水稻甲基化敏感随机扩增多态性分析评估干旱胁迫下的 DNA 甲基化模式

众所周知，当植物暴露于干旱等非生物胁迫时，DNA甲基化会调节基因表达。因此，深入了解 DNA 甲基化模式将有助于更好地了解与干旱适应相关的基因的表达谱。在本研究中，我们试图分析全基因组水平的 DNA 甲基化模式以及不同土壤水分状况下水稻中一些干旱响应基因的表达，即水坑、100% 和 60% 田间持水量（FC ）。甲基化敏感随机扩增多态性 DNA 分析用于鉴定 DNA 甲基化模式。我们观察到在 60% FC 下 DNA 甲基化增加，与水坑条件相比，在 100% FC 下甲基化减少。与混合条件相比，在其启动子区域具有 CpG 岛的蛋白磷酸酶 (PP2C) 和苯丙氨酸解氨酶 (PAL) 等基因在 100 和 60% FC 下的表达水平较低。热休克蛋白 70 (HSP70) 和 RNA 解旋酶 25 (RH25) 在其启动子区域中没有 CpG 岛，与水坑植物相比表现出增强的表达。在水稻中，增加的 DNA 甲基化似乎是与干旱反应相关的重要机制，这可能调节甲基化敏感基因的表达。干旱引起的 DNA 甲基化变化将有助于表观遗传机制。该研究提供的证据表明，干旱诱导的甲基化增加可能是与水稻等大田作物的适应反应相关的主要机制之一。