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Agrobacterium tumefaciens is a typical soil bacterium that causes crown gall disease in a variety of plant species. A. tumefaciens is capable of recognizing wound sites on a plant by detecting chemicals produced during the wound response of the plant. Laceration of the plant tissue causes the production of phenols and sugar molecules, which in turn trigger not only the chemotaxis of the bacteria towards the injury, but the processing of the tumor-inducing plasmid (Ti plasmid) as well as the expression of certain virulence genes. It is known that the bacterim inserts a segment of its Ti plasmid, the transfer DNA (T-DNA), into the plant at the wound site. The integration of the T-DNA allows for the production of certain plant hormones. It is the uncontrolled plant cell division stimulated by the overproduction of growth hormones that leads to the formation of tumors. Through experimental analysis we seek to identify mutant lines of Arabidopsis that are resistant to transformation, or hypersensitive to transformation. Identification of resistant or hypersensitive plant types is done through root tumor assays as well as GUS assays. In using these methods, it was determined that mutants show evidence of increased resistance while other mutants exhibit susceptibility to transformation similar to wild types. There is little known about the mechanism behind A. tumefacien attachment and transfer of T- DNA into plant cells, and it is our hope that identification of Arabidopsis genes associated with transformation in this screen will allow greater understanding of how the bacterial genetic material is transferred into the plant genome.