Combined genetic and physical map of the complex genome of Agrobacterium tumefaciens

A combined genetic and physical map of the Agrobacterium tumefaciens A348 ( derivative of C58) genome was constructed to address the discrepancy betwee n initial single-chromosome genetic maps and more recent physical mapping d ata supporting the presence of two nonhomologous chromosomes. The combined map confirms the two-chromosome genomic structure and the correspondence of the initial genetic maps to the circular chromosome. The linear chromosome is almost devoid of auxotrophic markers, which probably explains why it wa s missed by genetic mapping studies.