FIG 7.

The virulence of the T3SS mutants of MS2 and strain JZL7 on monocotyledonous and dicotyledonous plants. (A) Strain inoculation on banana seedlings. Every 100 μL of bacterial culture (OD₆₀₀ of 1.2 in LB medium) was injected into the basal stem and incubated at 30°C with 12-h alternating light-dark cycles for 7 days. The disease was assessed using the virulence scoring method described previously (17, 80). Red lines indicate the mean virulence score of the strains. (B) Strain inoculation on clivia leaves. Every 100 μL of bacterial culture was injected into the base of clivia leaf. (C and D) Strain inoculation on potato and radish slices. Bacterial cells of 2 μL were applied to the center of the tuber slices. Same volume of LB medium was inoculated as a negative control. All plants were kept in a growth chamber with controlled conditions of 28 ± 2°C, 75% ± 15% relative humidity and 24-h white light (7,350 lx) illumination until symptoms appeared. Visible macerate areas on clivia and potato and radish slices were measured using Image J 1.52a. Statistical analysis was performed on each group of data, and significantly different values (ANOVA P < 0.05) are indicated by different letters.