In vivo population dynamics. Pottedgreenhouse-grown grapefruit plants werepruned to produce uniformly aged shoots,
and three young shoots were inoculated per plant. Single colonies from isolates
6269 and 6369 were transferred separately
to nutrient broth and grown to log-phase.
The cultures were then pelleted by centrifugation,
resuspended in sterile tap water,
and adjusted to a 104
CFU/ml culture.
The bacterial suspensions were infiltrated
into 15 individual leaves on the young
grapefruit shoots, using a 1-ml tuberculin
syringe and 25-gauge needle. Inoculated
plants were kept in a quarantine greenhouse
at 20 to 30°C. Infiltrated leaves were
sampled at 0, 2, 4, 8, and 12 days after infiltration.
At each sample period, two leaf
disks (about 1 cm2
total) from infiltrated
tissue were triturated in sterile tissue grinders
containing 1 ml of sterile tap water.