Nuclear Matrix Attachment Regions and Transgene Expression in Plants.

DNA sequences called matrix attachment regions (MARs) or scaffold attachment regions (SARs) have recently attracted much attention because of their perceived capacity to increase levels of transgene expression and reduce transformant-to-transformant variation of transgene expression in both plants and animals. Work with these sequences is in its early stages and data that seem to be contradictory have been presented. We do not intend to resolve these controversies here (this will be accomplished by further research). Rather, we will discuss the hypothesized role of MARs in chromatin structure, how MARs are isolated and characterized, what effects MARs have had on the expression of transgenes and the models that have been evoked to explain those effects.