Efficient Splicing of the Tetrahymena Group I Intron in Transformed Tobacco Plants: Further Evidence for DNA to DNA Information Flow in Transformation by Agrobacterium tumefaciens. Gail Dinter-Gottlieb. Department of Bioscience and Biotechnology, Drexel University, Philadelphia, PA 19104 U.S.A. Tzion Fahima, and Nadine Pobjecky. Department of Bioscience and Biotechnology, Drexel University, Philadelphia, PA 19104 U.S.A. MPMI 4:500-506. Accepted 30 April 1991. Copyright 1991 The American Phytopathological Society.

We have used the self-splicing group I intron from Tetrahymena thermophila rRNA under control of the cauliflower mosaic virus (CaMV) 35S promoter to follow transformation of tobacco plants by the T-DNA of Agrobacterium tumefaciens. The presence of a potentially self-splicing RNA intermediate in the transformation process would allow splicing of the intron to occur, and the intron sequence would be absent from the plasmid integrated in the plant DNA. Assay of the integrated DNA demonstrated that in all cases, regardless of intron orientation, the intron cDNA was present in the plant. In constructions in which the intron precursor RNA under control of the CaMV promoter was in the correct orientation, efficient splicing of the intron from the precursor RNA occurred in the plant. This supports the view that T-DNA transformation involves a DNA to DNA transfer, without an RNA intermediate. It also demonstrates that efficient splicing of a nuclear ribosomal RNA intron from a protozoan can occur in a plant milieu.