FIG. 2.

Virulence of wild-type and AttR mutant bacteria on alfalfa stems. Bacteria were inoculated into needle wounds in alfalfa stems. The sites of inoculation were wrapped with parafilm to prevent drying. The stems were photographed 5 weeks later. The stem on the left was inoculated with the wild-type strain, C58, and the stem on the right was inoculated with the AttR mutant A205. The arrow points to the small tumor formed at the site of inoculation. About 50% of the sites inoculated with C58 formed tumors. None of the sites inoculated with A205 formed tumors.