Abstract
Transgene expression is notoriously variable between different, independently generated, transgenic plants. The eukaryotic genome, organized in a complex, heterogeneous structure termed chromatin, is not homogeneous for transcriptional activity. The variation of transgene expression is due to random integration into the chromosome. Specialized DNA sequences known as insulators protect genes from both the positive and negative influences of nearby chromatin. We use an insulator from the sea urchin Ars gene to function in plant cells. Normally, expression of an introduced chimeric GUS (β-glucuronidase) gene is inactivated in approximately 60% of the transformed tobacco BY2 clones. Transgenes containing the Ars insulator, however, were expressed in all transformed tobacco BY2 cells. These results suggest that the insulator functions to suppress the variation of transgene expression in tobacco BY2 cells.
