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Identification of tomato plant as a novel host model for Burkholderia pseudomallei.

Lee YH, Chen Y, Ouyang X, Gan YH - BMC Microbiol. (2010)

Bottom Line: This shows the importance of both T3SS1 and T3SS2 in bacterial pathogenesis in susceptible plants.The potential of B. pseudomallei as a plant pathogen raises new possibilities of exploiting plant as an alternative host for novel anti-infectives or virulence factor discovery.It also raises issues of biosecurity due to its classification as a potential bioterrorism agent.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, 117597, Singapore.

ABSTRACT

Background: Burkholderia pseudomallei is the causative agent for melioidosis, a disease with significant mortality and morbidity in endemic regions. Its versatility as a pathogen is reflected in its relatively huge 7.24 Mb genome and the presence of many virulence factors including three Type Three Secretion Systems known as T3SS1, T3SS2 and T3SS3. Besides being a human pathogen, it is able to infect and cause disease in many different animals and alternative hosts such as C. elegans.

Results: Its host range is further extended to include plants as we demonstrated the ability of B. pseudomallei and the closely related species B. thailandensis to infect susceptible tomato but not rice plants. Bacteria were found to multiply intercellularly and were found in the xylem vessels of the vascular bundle. Disease is substantially attenuated upon infection with bacterial mutants deficient in T3SS1 or T3SS2 and slightly attenuated upon infection with the T3SS3 mutant. This shows the importance of both T3SS1 and T3SS2 in bacterial pathogenesis in susceptible plants.

Conclusions: The potential of B. pseudomallei as a plant pathogen raises new possibilities of exploiting plant as an alternative host for novel anti-infectives or virulence factor discovery. It also raises issues of biosecurity due to its classification as a potential bioterrorism agent.

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Related in: MedlinePlus

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. Representative transmission electron micrographs show localization of bacteria in tomato leaf determined one day after infection. B) Leaves infected with B. thailandensis showing the longitudinal section of xylem vessel and C) leaves infected with B. pseudomallei showing the cross-sectional view. Bar represents 2 μm.
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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. Representative transmission electron micrographs show localization of bacteria in tomato leaf determined one day after infection. B) Leaves infected with B. thailandensis showing the longitudinal section of xylem vessel and C) leaves infected with B. pseudomallei showing the cross-sectional view. Bar represents 2 μm.

Mentions: 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.


Identification of tomato plant as a novel host model for Burkholderia pseudomallei.

Lee YH, Chen Y, Ouyang X, Gan YH - BMC Microbiol. (2010)

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. Representative transmission electron micrographs show localization of bacteria in tomato leaf determined one day after infection. B) Leaves infected with B. thailandensis showing the longitudinal section of xylem vessel and C) leaves infected with B. pseudomallei showing the cross-sectional view. Bar represents 2 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2823722&req=5

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. Representative transmission electron micrographs show localization of bacteria in tomato leaf determined one day after infection. B) Leaves infected with B. thailandensis showing the longitudinal section of xylem vessel and C) leaves infected with B. pseudomallei showing the cross-sectional view. Bar represents 2 μm.
Mentions: 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.

Bottom Line: This shows the importance of both T3SS1 and T3SS2 in bacterial pathogenesis in susceptible plants.The potential of B. pseudomallei as a plant pathogen raises new possibilities of exploiting plant as an alternative host for novel anti-infectives or virulence factor discovery.It also raises issues of biosecurity due to its classification as a potential bioterrorism agent.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, 117597, Singapore.

ABSTRACT

Background: Burkholderia pseudomallei is the causative agent for melioidosis, a disease with significant mortality and morbidity in endemic regions. Its versatility as a pathogen is reflected in its relatively huge 7.24 Mb genome and the presence of many virulence factors including three Type Three Secretion Systems known as T3SS1, T3SS2 and T3SS3. Besides being a human pathogen, it is able to infect and cause disease in many different animals and alternative hosts such as C. elegans.

Results: Its host range is further extended to include plants as we demonstrated the ability of B. pseudomallei and the closely related species B. thailandensis to infect susceptible tomato but not rice plants. Bacteria were found to multiply intercellularly and were found in the xylem vessels of the vascular bundle. Disease is substantially attenuated upon infection with bacterial mutants deficient in T3SS1 or T3SS2 and slightly attenuated upon infection with the T3SS3 mutant. This shows the importance of both T3SS1 and T3SS2 in bacterial pathogenesis in susceptible plants.

Conclusions: The potential of B. pseudomallei as a plant pathogen raises new possibilities of exploiting plant as an alternative host for novel anti-infectives or virulence factor discovery. It also raises issues of biosecurity due to its classification as a potential bioterrorism agent.

Show MeSH
Related in: MedlinePlus