Promoters of the rolA, B, and C genes of Agrobacterium rhizogenesare differentially regulated in transgenic plants.

Chimeric genes containing the beta-glucuronidase reporter gene under the control of the rolA, B, and C promoters of Agrobacterium rhizogenes are expressed in a regulated manner in transgenic plants. The intergenic region separating the rolB and C genes represents a bidirectional promoter. This bidirectional promoter regulates transcription for both genes in a similar fashion in aerial organs of the plants, but in a distinct way in roots. Moreover, both rolB and C promoter activities differ from those characteristic of the rolA promoter. Thus, promoters of bacterial origin show differential expression in transgenic plants, and regulation of roI gene expression plays a role in the biological effects caused by the rolA, B, and C genes.