Upward Curly Leaf 1 (UCL1) is an Arabidopsis thaliana E3 ligase that targets the Curly Leaf (CLF) SET-domain polycomb-group (PcG) protein for degradation via the ubiquitin-26S proteasome system. UCL1 is a paternally-expressed imprinted gene in the endosperm. To precisely locate the promoter elements required for UCL1 imprinting pattern, various gene constructs were created in which the imprinting control region (ICR), endosperm-specific expression (ENSE) element, and/or the linker sequence were altered. By fusing these constructs with a GUS reporter gene, GUS expression patterns were monitored after reciprocal crosses with wild-type Columbia-0 allowing the determination of parent-of-origin expression. Analysis of publicly-available data on the UCL1 promoter region facilitated the search for allele-specific DNA and H3K27 methylation patterns. Overall, three promoter elements are required for maternal repression of UCL1; the ICR sequence located from − 2.5 to − 2.4 kb upstream of the translation start site, a differentially methylated region 2 (DMR2) that overlaps the short ATLINE1-1 transposable element in the linker region, and a minimal 271 bp ENSE element. In addition, DNA methylation patterns in the DMR2 contribute to the repression of the maternal UCL1 allele. Our findings would help to understand how parent-of-origin epigenetic patterns are created and maintained in the endosperm.

向上卷曲叶1（UCL1）是拟南芥E3连接酶，其靶向卷曲叶（CLF）SET域聚梳组（PcG）蛋白，可通过遍在蛋白26S蛋白酶体系统降解。UCL1是胚乳中父本表达的基因。为了精确定位UCL1印迹模式所需的启动子元件，创建了多种基因构建体，其中的印迹控制区（ICR），胚乳特异性表达（ENSE）元件和/或接头序列发生了变化。通过将这些构建体与GUS报告基因融合，在与野生型Columbia-0进行双向杂交后，可以监测GUS表达模式，从而确定原产地表达。分析公开数据UCL1启动子区域有助于寻找等位基因特异性DNA和H3K27甲基化模式。总体而言，母亲抑制UCL1需要三个启动子元件。ICR序列位于翻译起始位点上游-2.5至-2.4 kb，差异甲基化区域2（DMR2）与连接子区域中的短ATLINE1-1可转座元件重叠，以及最小271 bp ENSE元件。此外，DMR2中的DNA甲基化模式有助于抑制母体UCL1等位基因。我们的发现将有助于了解如何在胚乳中创建和维持起源父母的表观遗传模式。