Abstract：
DEMETER-Like DNA demethylases (DMLs) are epigenetic regulators of many developmental and biological processes in plants. No comprehensive information about the DML gene family in citrus is available to date. Here, a total of three DML genes in the genomes of Citrus sinensis (named CsDML1-3) and C. clementina (named CcDML1-3) were identified and analyzed. They encode hydrophilic and relatively large proteins, with prediction of nuclear localization, containing the conserved domains and motifs typical of plant DMLs. Protein interaction network analysis suggested that they interact primarily with proteins related to the maintenance of DNA methylation and remodeling of chromatin. Analysis of their promoter regions led to the identification of several cis-acting regulatory elements involved in stress response, including drought, heat and cold stresses. The presence of several miRNA targets and potential phosphorylation sites suggest that their expression is also regulated at post-transcriptional and post-translational levels. RNA-Seq data and quantitative real-time PCR analysis showed a low and drought-regulated gene expression of the citrus DMLs in different plant tissues. CsDML1 and CsDML3 were also differentially regulated by deficit irrigation in fruits at different developmental stages, with a positive and significant correlation found between CsDML1 and PHYTOENE SYNTHASE (PSY) and between CsDML3 and ATP CITRATE LYASEs (ACLs) and ZETA-CAROTENE DESATURASE (ZDS) gene expression. These results indicate that the citrus DMLs are potentially functional enzymes involved in developmental processes and drought stress-adaptive responses, providing a useful reference for further investigation of their functions and applications on the citrus improvement.
摘要：
DEMETER-likeDNA脱甲基酶（DMLs）是植物许多发育和生物学过程的表观遗传调节因子。迄今为止，尚无有关柑橘中DML基因家族的全面信息。这里,对柑橘(CsDML1-3)和柑橘(CcDML1-3)基因组中的三个DML基因进行了鉴定和分析。它们编码亲水性和相对较大的蛋白质，随着核定位的预测，包含植物DMLs典型的保守域和基序。蛋白质相互作用网络分析表明，它们主要与DNA甲基化维持和染色质重塑相关的蛋白质相互作用。对其启动子区域的分析导致鉴定了参与应激反应的几种顺式作用调控元件，包括干旱,热和冷应力。几个miRNA靶标和潜在磷酸化位点的存在表明它们的表达也在转录后和翻译后水平上被调节。RNA-Seq数据和定量实时PCR分析显示，柑橘DMLs在不同植物组织中的基因表达较低且受干旱调控。CsDML1和CsDML3也受到不同发育阶段果实亏缺灌溉的差异调控,在CsDML1和植物酶合成酶（PSY）之间以及CsDML3和ATPCI裂解酶（ACL）与ZTA-胡萝卜素脱脂酶（ZDS）基因表达之间存在正相关。这些结果表明，柑橘DMLs是参与发育过程和干旱胁迫适应性反应的潜在功能酶，为进一步研究其在柑橘改良中的作用和应用提供了有益的参考。
