Promoter analysis of the highly expressed rolC and rolD root-inducing genes of Agrobacterium rhizogenes: enhancer and tissue-specific DNA determinants are dissociated

Abstract

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 β-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.