FIG 4 .

Differential virulence of the R. solanacearum UW551 scrA mutant on susceptible and resistant hosts. (A to D) The wild-type R. solanacearum UW551 (WT) (blue triangles) and scrA mutant (red squares) were inoculated by soil soaking onto the unwounded roots of susceptible tomato cultivar Bonny Best (A), quantitatively resistant tomato cultivar Hawaii7996 (B), potato cultivar Russet Norkotah (C), and solanaceous nightshade (D). Plant symptoms were rated daily on a disease index scale from 0 to 4 (0 for healthy or no leaf area wilted, 1 for 1 to 25% of the leaf area wilted, 2 for 26 to 50% of the leaf area wilted, 3 for 51 to 75% of the leaf area wilted, and 4 for 76 to 100% of the leaf area wilted). Each point indicates the mean disease index for three independent inoculations (A, B, and D) or one experiment (C); the scrA mutant was significantly less virulent than the wild type on each host (P < 0.001 by repeated measures ANOVA).