FIG 2.

AlgU-dependent downregulation of fliC expression reduces indicators of PTI in N. benthamiana and tomato plants. (A) PTI-dependent HR cell death suppression assay. N. benthamiana leaves were inoculated with a suspension containing 5 × 10⁷ CFU/ml of test strains (top circles) and then incubated 6 hours before partially overlapping challenge inoculation with a suspension of 2 × 10⁷ CFU/ml of the cell death-eliciting wild-type DC3000 strain (bottom circles) and incubated an additional 48 hours before evaluation. The genotype of each test strain and the number of times each test strain induced PTI as a fraction of number of times tested are shown above and below each photograph, respectively. +AlgU expression and empty vector control are the same as in Fig. 1. +FliC expression was provided by pME6010-fliC, which carries DC3000 fliC under the control of its native promoter (7). (B) L-012 chemiluminescence ROS assay for N. benthamiana leaves at 15 h after inoculation with the indicated strains at 5 × 10⁸ CFU/ml. Individual points show total photon counts collected over 30 minutes for 18 replicates; box plots show the interquartile range (IQR), split by the median; and whiskers show the range of data that are within 1.5 × IQR above and below the first and third quartiles, respectively. Statistical significance was tested using linear mixed effects modeling. Letters indicate Tukey-Kramer honestly significant difference (HSD) mean comparison results; means not connected by letters are significantly different. (C) Mean relative expression level of WRKY28 (16) in tomato plants (Solanum lycopersicum) 6 h after inoculation with 5 × 10⁵ CFU/ml of algU mucAB and/or fliC mutant derivatives relative to plants infected with DC3000 D36E. Error bars show standard deviation.