4.4 X. campestris inoculation and disease evaluation
X. campestris pv. vesicatoria strain 85-10 (Xcv ) was used for bacterial infection analysis. Pathogenicity assays were performed according to (O’Donnell et al., 2001). Briefly, bacterial cultures were grown in Luria Bertani (LB) medium containing 100 mg L−1 of rifampicin and 300 mg L−1 of streptomycin, overnight at 28°C. Log phase bacterial cultures were harvested and re-suspended in 10 mM MgCl2 at a final concentration of 105 CFU mL-1(OD600=0.0002). The fourth leaf of 5-week-old tomato plants were vacuum immersed with the bacterial suspensions. Three days after infiltration, three leaf discs of 0.9 cm diameter were sampled from at least four plants from each genotype and ground in 1 ml of 10 mM MgCl2. Bacterial pathogen CFU were determined by plating and counting the resulting colonies (Lund et al., 1998). Negative controls consisted of 10 mM MgCl2 without pathogen inoculation. Plants were subjected to 2 RZW cycles followed by three recovery days before they were infected by Xcv as mentioned above.