VIGS of NPR1 interferes with XopJ-dependent phenotypes in pepper.

(A) qRT-PCR analysis of NPR1 mRNA level in NPR1 silenced pepper plants. Relative expression levels at 21 dpi are shown. Actin expression was used to normalize the expression value in each sample, and relative expression values were determined against pTRV2-GFPsil plants. (B) Xcv (vector), Xcv ΔxopJ (vector), Xcv ΔxopJ (XopJ-HA) were infiltrated at a bacterial density of 2×108 cfu ml−1 into leaves of pTRV2-GFPsil and pTRV2-NPR1 plants. Plant reactions were photographed at 3 d post infection (dpi). The number of leaves showing necrosis is indicated below the appropriate construct. (C) Leaves were infiltrated with strains indicated in the figure. At 3 dpi proteasome activity in total leaf extracts was determined by monitoring the breakdown of the fluorogenic peptide suc-LLVY-NH-AMC at 30°C in a fluorescence spectrophotometer. Data represent the mean SD (n = 3). Significant differences were calculated using Student's t-test and are indicated by: *, P