Influence of DNA methylation on transgene expression

DNA methylation plays an important role in gene expression in eukaryote. But DNA methylation of transgene usually leads to target gene silencing in plant genetic engineering. In this research, reporter gene β-glucuronidase (GUS) gene (uidA) was introduced into tobaccosvia Agrobacterium-mediated transformation method, and the foreign uidA gene became inactive in some transgenic tobaccos. No mRNA ofuidA was detected in these plants by Northern blotting analysis, and DNA methylation of promoter region was found. The results indicated that gene silencing might be caused by DNA methylation of promoter.