Agrobacterium tumefaciens is a gram negative soil bacterium induces the formation of crown galls or tumours at plant wound sites. During tumorigenesis, A. tumefaciens transfers a part of its tumour inducing (Ti) plasmid, the T-DNA, to the plant cell where it then integrates. A. tumefaciens is also able to transfer T-DNA to Saccharomyces cerevisiae and Kluyveromyces lactis. We have studied in these hosts the mechanism of T-DNA integration. When a T-DNA carrying sequences homologous to the yeast genome was transferred to S. cerevisiae it integrated efficiently via homologous recombination. This demonstrates that the mechanism of T-DNA integration is determined by the host cell. Furthermore, a T-DNA lacking homology with the S. cerevisiae genome can integrate via illegitimate recombination. We have been able to demonstrate that A. tumefaciens is able to transform the filamentous fungus Aspergillus awamori, demonstrating for the first time DNA transfer between a prokaryote and a fungus. Analysis of the transformed fungi showed that in most cases the T-DNA was present as a single intact copy in the fungal genome. The T-DNA had integrated into the genome via an illegitimate recombination mechanism, as shown by sequencing the genomic DNA flanking the integrated T-DNA copies.
Fungal Genet. Newsl. 46 (Supl):
Full conference title:
Fungal Genetics Conference 20th
- Fungal Genetics Conference 20th (1999)