Figure 3. Virulence assays on apple shoots.

A. Symptoms caused by Erwinia amylovora wild type (WT), amyR mutant, complementation strain and WT containing pAmyR2 plasmid on shoots of apple cv. Gala at 8 dpi. Virulence assays were performed using young annual shoots by pricking the tip with a needle, and pipetting 5 µl of pathogen suspension (OD₆₀₀ = 0.1) onto the wounded tissue. The experiment was performed at least three times with similar results. B. Symptoms caused by WT and various strains on leaves of apple cv. Red Delicious at 8 dpi. Young leaves of Red Delicious plants were inoculated with scissors dipped in a bacterial suspension (OD₆₀₀ = 0.1). dpi: days post inoculation.