For a phytopathogen to successfully colonize the plant, it must be able to replicate intercellularly [19]. To determine whether bacteria are able to replicate intercellularly, we sampled CFTR inhibitor leaves from two representative plantlets which had been inoculated with bacteria via unwounded roots at 1, 3, 5 and 7 days post-inoculation. Three leaves were sampled at each time-point per plantlet. Both plantlets showed a progressive increase in bacterial load in their leaves over time (Fig 1D). Susceptibility of tomato plantlets to B. pseudomallei infection Having established that B. thailandensis can infect tomato

plantlets and cause disease, we determine whether B. pseudomallei would similarly infect tomato plantlets. We included strains isolated from humans, animals or the environment such as two clinical isolates (K96243 and KHW), 3-MA molecular weight a kangaroo isolate 561, two bird isolates (612 and 490) and two soil isolates (77/96 and 109/96) on their ability to infect tomato plants. B. pseudomallei is able to infect tomato plantlets to a similar degree as B. thailandensis with almost identical disease symptoms. All isolates were able to infect and cause disease to a similar extent (Fig 2), showing that the ability to infect susceptible plants is unlikely to be strain-specific. Figure 2 Infection of tomato plantlets with different

B. pseudomallei isolates. KHW and K9 (K96243) are clinical isolates, 77/96 and 109/96 are soil isolates, 561 is isolated selleckchem from a kangaroo, 612 from a crown pigeon and 490 from a Bird of Paradise. The average disease score was calculated based on 12 plantlets per bacterial isolate cumulative from two experiments. selleck inhibitor Localization of bacteria at site of infection Having established the ability of both B. thailandensis and B. pseudomallei to be phytopathogens capable of infecting tomato plants, we next examined the localization of the bacteria upon inoculation into the leaf via TEM. We first

examined whether bacteria inoculated into the leaves were able to survive and replicate. To ensure that there were no bacteria on the leaf surfaces, the leaves were surface sterilized with bleach and washed in sterile water before weighing and maceration. B. thailandensis was able to replicate in the leaves after inoculation (Fig 3A). The number of bacteria increased by about 10 fold three days after infection although the numbers did not reach statistical significance by the student t test (p > 0.05). When examined under TEM, B. pseudomallei and B. thailandensis could be found in the xylem of the vascular bundle of the inoculated leaf (Fig 3B-C). The rest of the surrounding cells were not colonized, suggesting that the bacteria spread to the rest of plant through the xylem vessels. Figure 3 Replication and localization of bacteria in tomato leaves. A) B. thailandensis multiplication in tomato leaves was measured at one and three days post inoculation. The graph is representative of two separate experiments.