Epigenetic regulation of the individual genomes originated from male and female germ cells in somatic cells of Brassica napus

本研究的目的是鉴定在甘蓝型油菜中有印迹的基因。在大多数情况下，印迹基因在生殖系细胞成熟过程中被胞嘧啶甲基化标记。因此，我们开始鉴定花粉中与子房相比高度甲基化的基因。利用甲基化敏感表征差异分析（MS-RDA），鉴定了花粉中16个特异性甲基化基因；14个基因由核基因组编码，1个基因由叶绿体基因组编码，1个基因由线粒体基因组编码。其中，本研究中发现的两个新基因在甲基化和表达方面进行了详细分析。其中一个（BnMyb1）与植物和动物的Myb基因具有高度同源性。另一个（BnMRA19）与拟南芥基因组预测的一个蛋白同源。这两个基因在花粉中都有特异性甲基化的区域。不出所料，BnMyb基因在花粉中不表达，而在子房中表达。此外，BnMRA19基因在花粉中不表达，但有趣的是，在花粉成熟早期短暂表达。这些结果表明BnMyb1和BnMRA19基因是候选的印迹基因。进一步的分析可能会证实这一点。

The aim of this study was to identify the genes that were imprinted in Brassica napus. In most cases, imprinted genes are marked by cytosine methylation during maturation of germ line cells. Therefore, we started to identify genes, which were highly methylated in pollen as compared to ovary.By using methylation-sensitive representational difference assay (MS-RDA), 16 genes specifically methylated in the pollen were identified ; 14 genes encoded by nuclear genome, one encoded by chloroplast genome and one encoded by mitochondrial genome.Of these, two genes that were found as novel genes in this study, were analyzed in detail with respects to methylation and expression. One (BnMyb1) had a high homology to the Myb gene of plant and animal. Another one (BnMRA19) had homology to a protein that was predicted from the Arabidopsis thaliana genome. Both genes had regions specifically methylated in the pollen. As expected, the BnMyb gene was not expressed in the pollen, but expressed in the ovary. Also, the BnMRA19 gene was not expressed in the pollen, but interestingly, transiently expressed in an early stage of pollen maturation. These results implied that BnMyb1 and BnMRA19 genes are candidate imprinted genes. Further analysis may confirm this.