Mei Xiupeng, Liu Chaoxian, Yu Tingting, Liu Xiaoli, Xu De, Wang Jiuguang, Wang Guoqiang, Cai Yilin
Maize Research Institute, Key Laboratory of Biotechnology and Crop Quality Improvement, Ministry of Agriculture, Southwest University, Chongqing, China.
Mol Genet Genomics. 2015 Oct;290(5):1819-31. doi: 10.1007/s00438-015-1043-5. Epub 2015 Apr 8.
Gene imprinting describes an epigenetic phenomenon, whereby genetically identical alleles are differentially expressed dependent on parent-of-origin. Some imprinted genes belonged to NUCLEAR FACTOR Y (NF-Y) transcription factors, which were involved in many important metabolic processes in plant. The characterizations of imprinted genes are of great importance for their function exploration. In this paper, 15 non-redundant NF-YC genes were identified in the maize genome and the paternally expressed gene NF-YC8 was further analyzed. NF-YC8 primarily expressed in maize immature ear and tassel and phylogenetic analysis showed that NF-YC8 was highly homologous with Arabidopsis thaliana NF-YC2 genes which function in regulation of the flowering processes, ER stress response. Furthermore, NF-YC8 was a differential, gene-specific imprinted gene at 14 DAP and persistently imprinted throughout later endosperm development in the B73/Mo17 genetic background. Bisulfite sequencing for NF-YC8 in maize endosperm showed that the paternal alleles were higher methylated (CG, CHG and CHH contexts) than maternal alleles in the 5' upstream region, and the coding region was highly methylated in CG context. Additionally, TE (CG, CHG and CHH contexts) and repetitive region (CG and CHG contexts) were all highly methylated. These results are the first description of evolution and molecular characterization of maize NF-YC8 and will provide new references for maize NF-YC genetic analysis.
基因印记描述了一种表观遗传现象，即基因相同的等位基因根据其亲本来源而有差异地表达。一些印记基因属于核因子Y（NF-Y）转录因子，它们参与植物许多重要的代谢过程。对印记基因的表征对于探索其功能非常重要。本文在玉米基因组中鉴定出15个非冗余的NF-YC基因，并对父本表达的基因NF-YC8进行了进一步分析。NF-YC8主要在玉米未成熟穗和雄穗中表达，系统发育分析表明，NF-YC8与拟南芥中参与开花过程调控、内质网应激反应的NF-YC2基因高度同源。此外，在B73/Mo17遗传背景下，NF-YC8在授粉后14天是一个差异的、基因特异性的印记基因，并在胚乳发育后期持续保持印记状态。对玉米胚乳中NF-YC8的亚硫酸氢盐测序表明，在5'上游区域，父本等位基因比母本等位基因甲基化程度更高（CG、CHG和CHH背景），并且编码区在CG背景下高度甲基化。此外，转座元件（CG、CHG和CHH背景）和重复区域（CG和CHG背景）均高度甲基化。这些结果首次描述了玉米NF-YC8的进化和分子特征，将为玉米NF-YC基因分析提供新的参考。
