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.