Reduced rhizosphere colonization ability of Agrobacterium tumefaciens chromosomal virulence (chv) mutants

Mutations in the chromosomal virulence (chv) region of A. tumefaciens strain A723 reduce virulence, motility, and ability of the bacteria to bind to plant cells. We conducted experiments to assess the ability of chv mutants to colonize the rhizosphere of Pisum sativum. The mutation had no effect on ability of bacteria to grow with a defined number of root cap cells as the sole carbon and nitrogen source. Ten days after inoculation, there were up to 103-fold more wild type than chv mutant bacteria present in the rhizosphere of inoculated plants.