Silencing of SlEpk1 compromises resistance to Pseudomonas syringae pv. tabaci (AvrPto). (A) N. benthamiana (Nb) 35S:Pto plants were silenced for the genes shown and subsequently syringe-infiltrated with 5 × 104cfu/ml P. s. pv. tabaci expressing avrPto (A) or empty vector (EV). Photographs were taken 4 days after inoculation. (B) Percentage of the infiltrated leaf circles that developed disease. Asterisks indicate significant differences compared with Ec1-silenced plants using Fisher’s exact test (P <0.05). Six plants were used per silencing construct. (C) P. s. tabaci (avrPto) populations in leaves. Leaves of silenced plants were infiltrated with 6 × 104cfu/ml P. s. tabaci (avrPto) and sampled to measure bacterial populations at the times shown. Bars represent the mean of six plants per construct with their corresponding standard error. Asterisks indicate significant differences compared with Ec1-silenced plants using a Student’s t-test (P <0.05). (D) Disease lesions at 9 days after infiltration; Ec1, Escherichia coli fragment 1 (negative control).