Analysis of Agrobacterium tumefaciens virulence mutants in leaf discs.

The leaf disc transformation system provides a simple means to score expression of various T-DNA markers within days of infection by Agrobacterium tumefaciens as well as long-term selection for growth of transformed callus and shoots. In this report, we describe the application of this system to evaluation of marker transfer and integration in a comprehensive set of defined avirulent mutants of A. tumefaciens. We conclude that virC is not essential when the T-DNA is present on a binary vector. The most likely explanation for this is that the virC gene product is involved in generation of a T-DNA intermediate.