The Influences of Two Plant Nuclear Matrix Attachment Regions (MARs) on Gene Expression in Transgenic Plants

Nuclear matrix attachment regions (MARs) are thought to influencegene expression by anchoring active chromatin to the proteinaceousnuclear matrix. In this study, two plant DNA fragments withstrong MAR activity were selected and tested for their effectson expression of a linked reporter gene in transgenic tobacco.One MAR was isolated from the 5' flanking region of a pea vicilingene previously reported to be expressed in a copy number-dependentmanner in transgenic tobacco. A second MAR was isolated fromthe genome of Arabidopsis thaliana by preselection for autonomouslyreplicating sequence (ARS) activity in yeast. Flanking copiesof the A. thaliana MAR stimulated median reporter gene expressionin transgenic plants by five to ten fold. Neither MAR significantlyreduced the variation in transgene expression between individualtransformants, or conferred copy number-dependence in gene expression. (Received July 24, 1997; Accepted November 10, 1997)