Infection experiments with Pseudomonas syringae pv. tomato DC3000 (Pst) and P. cichorii ATCC10857/DSM50259 (Pci) wild‐type (WT) and ∆wbpL deletion mutants. Arabidopsis thaliana plants were inoculated by spraying (A, n = 5, mean ± SEM) or syringe‐infiltration of leaves (B, n = 4, mean ± SEM) with Pst WT or Pst ∆wbpL suspension. Samples were taken 4 and 72 h post‐inoculation (hpi). (P < 0.001, multiple t‐test, experiments were repeated at least three times with similar results). (C) Lettuce midrib was stab infected with Pci WT and Pci ∆wbpL and the size of the emerging lesions was measured 2 days post‐inoculation (dpi) (Fig. S2A, n = 6, P < 0.05, Wilcoxon signed‐rank test, experiment was repeated at least three times with similar results). (D) Lettuce leaves were sprayed with Pci WT or Pci ∆wbpL suspensions and disease symptoms were monitored over time. The picture was taken 9 dpi. The original image is provided in the supporting information (Fig. S2B).