Development of plant promoter expression vectors and their use for analysis of differential activity of nopaline synthase promoter in transformed tobacco cells.

I have developed promoter expression binary vectors based on the tumor-inducing plasmid of Agrobacterium tumefaciens to facilitate elucidation of plant gene regulation. Promoter activity can be determined by inserting DNA fragments into the multiple cloning sites of the vectors forming transcriptional and/or translational fusions between the cat structural gene and an inserted promoter region. The activity of the nopaline synthase (nos) promoter was demonstrated with the vector. However, three animal promoters tested with this system showed no measurable activity in plant cells. Examination of 40 independently derived transformed tissues revealed a 200-fold difference in the nos promoter activity. Furthermore, there is no apparent correlation between the neomycin phosphotransferase and chloramphenicol acetyltransferase activities, although both genes are closely linked and under control of identical nos promoters. These results indicate that vast differences in promoter activity of transferred genes can occur within the same cell, as well as in independently derived cell lines.