The WxxxE and ERMRS motifs are required for the virulence activity of P. syringae pv. tomato (Pto) AvrE1 in A. thaliana. A, a diagram of the AvrE1 protein, indicating the locations of the motifs and various mutations introduced. Numbers indicate the amino acid positions. B, bacterial populations in A. thaliana Col-0 leaves at 3 days after inoculation. Leaves were inoculated by infiltration with 1 × 106 CFU/ml of Pto ΔCEL bacteria carrying wild-type or mutant pAVRE and pAVRF. C, disease symptoms at 3 days after inoculation. D, immunoblot analysis of the production and secretion of wild-type and mutant AvrE1 proteins in Pto ΔCEL. Bacteria were grown in hrp-inducing liquid medium. Cultures were separated into supernatant (Sup) and cell (Cell) fractions by centrifugation. AvrE1 proteins in total lysates were detected by immunoblotting using an AvrE1 antibody.