Tobacco matrix attachment region sequence increased transgene expression levels in rice plants

In this study, six plasmids were constructed to study the effects of the tobacco Rb7 matrix attachment region (MAR) sequence on rice transgene expression. Among them, each of four plasmids contained two identical copies of the MAR sequence flanking two different reporter genes, which encode the green fluorescent protein and beta -glucuronidase. Two control plasmids contained no MAR sequences. Microprojectile bombardment was used to separately introduce these six plasmids into rice calli. Transgenic rice plants were regenerated, and gene expression was measured in rice leaf extracts of two-month-old transgenic plants. By comparing transgenic plants with the corresponding control plants, transgenic plants harboring each of four plasmids that included the MAR sequence resulted in average gene expression levels enhanced by 3.3-fold, 18-fold, 376-fold and 650-fold. These results suggest that the same MAR sequence can affect the expression of different genes to different extents. One goal of plant scientists and breeders is to maximize expression levels of transgenes, especially in the production of transgene-encoded protein. Therefore, inclusion of the Rb7 MAR sequence would be beneficial.