In planta analysis of the Agrobacterium tumefaciens T-cyt gene promoter: identification of an upstream region essential for promoter activity in leaf, stem and root cells of transgenic tobacco.

The promoter region of the Agrobacterium tumefaciens T-cyt gene was fused to a beta-glucuronidase (gusA) reporter gene and introduced into tobacco plants. Detection of gusA expression in transgenic F1 progeny revealed that the T-cyt promoter is active in many, if not all, cell types in leaves, stems and roots of fully developed plants. Developmental stage-dependent promoter activity was observed in seedlings. Analysis of 5'-deleted promoter fragments showed that sequences located between positions -185 and -139 with respect to the T-cyt translational start codon are essential for T-cyt promoter activity in transfected tobacco protoplasts as well as in transformed tobacco plants.