XopJ suppresses cell death during the compatible Xcv-pepper interaction.

(A) Xcv (vector), Xcv ΔxopJ (vector), Xcv ΔxopJ (XopJ-HA), XopJ (G2A-HA) and (C235A-HA) were inoculated at a bacterial density of 2×108 cfu ml−1 into leaves of pepper ECW plants. Leaf phenotype was photographed at 3 d post infection (dpi). (B) Protein extracts from pepper leaves infiltrated with 1 mM MgCl2, Xcv (vector), Xcv ΔxopJ (vector), Xcv ΔxopJ (XopJ-HA), XopJ (G2A-HA) and (C235A-HA) at 3 dpi were prepared. Equal volumes representing approximately equal protein amounts of each extract were immunoblotted and proteins were detected using anti-HA antiserum. (C) Trypan blue staining of infected tissue of ECW plants reveals reduced cell death in the presence of functional XopJ. Xcv (vector), Xcv ΔxopJ (vector), Xcv ΔxopJ (XopJ-HA), XopJ (G2A-HA) and (C235A-HA) were inoculated at a bacterial density of 2×108 cfu ml−1 into leaves of pepper ECW plants. Samples of infected and untreated leaves were taken 3 dpi and stained with trypan blue. Dead plant cells stain blue. Grey and black spots represent calcium oxalate crystals. (D) Summary of observed phenotypes. 20 pepper plants were infected with the different Xcv strains indicated in this figure and then scored for phenotype development at 3 dpi. (E) Delivery of XopJ by Xcv leads to reduced ion leakage in pepper. Ion leakage was measured in pepper plants infected with. Xcv (vector), Xcv ΔxopJ (vector), Xcv ΔxopJ (XopJ-HA), XopJ (G2A-HA) and (C235A-HA). Conductivity was measured at the time points indicated. Data represent the mean SD (n = 3). Significant differences are indicated by asterisks (* P<0.05; ** P<0.01; *** P<0.001) and were calculated using Student's t-test.