Transcription of cauliflower mosaic virus integrated into plant genomes.

A full-length copy of cauliflower mosaic virus (CaMV) was introduced into the T DNA of the Agrobacterium Ti plasmid and integrated into plant genomes. Northern analysis of turnip galls revealed two transcripts derived from the integrated CaMV. A 1900-nucleotide (1.9 kb) transcript arises from the region VI area of the genome and is the same size as the region VI transcript found in CaMV-infected leaves. A larger 7.5-kb transcript initiates at or near the other known CaMV promoter, which in infected cells directs synthesis of a full-length transcript, and terminates in adjacent T-DNA sequences. Comparison of the two transcripts in galls from seven plant species showed wide variation of both the ratios of the two transcripts within one species and of their levels between species.