AGROBACTERIUM-TUMEFACIENS-MEDIATED TRANSFORMATION OF YEAST

Agrobacterium tumefaciens transfers a piece of its Ti plasmid DNA (tra nsferred DNA or T-DNA) into plant cells during crown gall tumorigenesi s. A. tumefaciens can transfer its T-DNA to a wide variety of hosts, i ncluding both dicotyledonous and monocotyledonous plants. We show that the host range of A. tumefaciens can be extended to include Saccharom yces cerevisiae. Additionally, we demonstrate that while T-DNA transfe r into S. cerevisiae is very similar to T-DNA transfer into plants, th e requirements are not entirely conserved. The Ti plasmid-encoded vir genes of A. tumefaciens that are required for T-DNA transfer into plan ts are also required for T-DNA transfer into S. cerevisiae, as is vir gene induction. However, mutations in the chromosomal virulence genes of A. tumefaciens involved in attachment to plant cells have no effect on the efficiency of T-DNA transfer into S. cerevisiae. We also demon strate that transformation efficiency is improved 500-fold by the addi tion of yeast telomeric sequences within the T-DNA sequence.