FIG 5.
Both DksA and ppGpp are required for bacterial growth in planta. (A) Growth of the E. amylovora WT strain, the relA, spoT, and dksA single mutants, and their corresponding complementation strains in immature pears. (B) Growth of the E. amylovora WT strain, the relA/dksA and relA/spoT (ppGpp0) double mutants, and their corresponding complementation strains in immature pears. Immature pears (cv. ‘Bartlett’) were surface sterilized, pricked with a sterile needle, and inoculated with 2 μl of bacterial suspension. Tissue surrounding the inoculation site was excised with a no. 4 cork borer and homogenized in 1 ml of 0.5× PBS. Bacterial growth within the pear tissue was monitored at 1, 2, and 3 days postinoculation by dilution plating on LB medium with appropriate antibiotics. d, day.