PROMOTER ANALYSIS OF THE HIGHLY EXPRESSED ROLC AND ROLD ROOT-INDUCING GENES OF AGROBACTERIUM-RHIZOGENES - ENHANCER AND TISSUE-SPECIFIC DNA DETERMINANTS ARE DISSOCIATED

Promoter activity of the leaf-specific rolC and root-specific rolD root-inducing genes of Agrobacterium rhizogenes strain A4 Ri T-DNA was analysed by serial deletions of their 5' non-coding regions and fusion to the beta-glucuronidase reporter gene. High activity of the rolC promoter in both roots and leaves required the presence of a sequence located at least 350 bp upstream of the mRNA start site within a 455 bp HindIII-PvuII fragment. Deletions removing this region lowered the activity of the rolC promoter and increased its root-specificity. The rolD promoter is highly specific to regenerating plants. Deletions of the upstream region led to high expression in roots of both young and mature tobacco plants.