A Ti-plasmid determined function is responsible for chemotaxis ofAgrobacterium tumefacienstowards the plant wound product acetosyringone

Agrobacterium tumefaciens C58C1[pTiB6S3] harbouring the octopine Ti-plasmid pTiB6S3, showed positive chemotaxis towards the phenolic plant wound exudate acetosyringone (AS). Maximal attraction was observed at 10−7 M. In contrast, A. tumefaciens C58C1 lacking a Ti-plasmid, exhibited no chemotactic response to AS. However, chemotaxis did occur towards the plant phenolic vanillyl alcohol, but at higher concentrations (10−2 M) and in both Ti-plasmid-containing and cured A. tumefaciens. These results indicate that at least one Ti-plasmid function is involved in the specific chemotactic response to AS, although chemotaxis per se is not Ti-plasmid-encoded. This correlates well with the specific induction of vir-operons mediated by this plant wound product [1].