Agrobacterium and plant genes involved in T-DNA transfer and integration

The phytopathogenic bacterium Agrobacterium tumefaciens genetically transfo rms plants by transferring a portion of the resident Ti-plasmid, the T-DNA, to the plant. Accompanying the T-DNA into the plant cell is a number of vi rulence (Vir) proteins. These proteins may aid in T-DNA transfer, nuclear t argeting, and integration into the plant genome. Other virulence proteins o n the bacterial surface form, a pilus through which the T-DNA and the trans ferred proteins may translocate. Although the roles of these virulence prot eins within the bacterium are relatively well understood, less is known abo ut their roles in the plant cell. In addition, the role of plant-encoded pr oteins in the transformation process is virtually unknown. In this article, I review what is currently known about the functions of virulence and plan t proteins in several aspects of the Agrobacterium transformation process.