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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

B. thailandensis infection and replication in tomato plantlets. Tomato plantlets were infected with B. thailandensis and monitored over a period of seven days. On day 7, representative photographs of the uninfected plantlets (A) and the infected plantlets (B) were taken. (C) Tomato plantlets infected with B. thailandensis were scored daily based on the extent of disease symptoms on an index from 1 - 5 over a period of seven days. The average score was calculated based on at least 100 plantlets cumulative from several experiments. (D) Each graph represents bacterial counts from leaves of one B. thailandensis infected plantlet over days 1, 3, 5 and 7. Each symbol L represents one leaf.
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Figure 1: B. thailandensis infection and replication in tomato plantlets. Tomato plantlets were infected with B. thailandensis and monitored over a period of seven days. On day 7, representative photographs of the uninfected plantlets (A) and the infected plantlets (B) were taken. (C) Tomato plantlets infected with B. thailandensis were scored daily based on the extent of disease symptoms on an index from 1 - 5 over a period of seven days. The average score was calculated based on at least 100 plantlets cumulative from several experiments. (D) Each graph represents bacterial counts from leaves of one B. thailandensis infected plantlet over days 1, 3, 5 and 7. Each symbol L represents one leaf.

Mentions: To mimic infection via a possible natural route, the unwounded roots of tomato plantlets were immersed in media inoculated with 1 × 107 cfu of bacteria. Only the roots were in contact with the inoculum. Tomato plantlets infected via the roots by B. thailandensis showed progressive symptoms such as yellowing of leaves, blackening of the leaf veins, wilting and necrosis whereas uninfected plantlets remained healthy and did not show any disease symptoms throughout the period (Fig 1A-B). Most infected plantlets were dead on day 7. All plantlets were monitored over a period of seven days. Disease was scored daily for every plantlet on an index from 1-5 based on the extent of symptoms presented as described in Methods. The average disease score for a particular day represent the mean disease scores for all the plantlets with the same treatment on that day. As infection progressed over time, the average disease score for B. thailandensis-infected plants increased progressively, reaching a maximum disease score of 5 on day 7 (Fig 1C). In contrast, plantlets infected with E. coli in the same manner via the roots showed a slight progression of average disease scores over time and reached a maximum disease score of 2 on day 7 (Fig 1C), demonstrating that the extensive disease and death seen was specific to B. thailandensis infection and not due to non-specific stress induced by the experimental manipulations.


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

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

B. thailandensis infection and replication in tomato plantlets. Tomato plantlets were infected with B. thailandensis and monitored over a period of seven days. On day 7, representative photographs of the uninfected plantlets (A) and the infected plantlets (B) were taken. (C) Tomato plantlets infected with B. thailandensis were scored daily based on the extent of disease symptoms on an index from 1 - 5 over a period of seven days. The average score was calculated based on at least 100 plantlets cumulative from several experiments. (D) Each graph represents bacterial counts from leaves of one B. thailandensis infected plantlet over days 1, 3, 5 and 7. Each symbol L represents one leaf.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 1: B. thailandensis infection and replication in tomato plantlets. Tomato plantlets were infected with B. thailandensis and monitored over a period of seven days. On day 7, representative photographs of the uninfected plantlets (A) and the infected plantlets (B) were taken. (C) Tomato plantlets infected with B. thailandensis were scored daily based on the extent of disease symptoms on an index from 1 - 5 over a period of seven days. The average score was calculated based on at least 100 plantlets cumulative from several experiments. (D) Each graph represents bacterial counts from leaves of one B. thailandensis infected plantlet over days 1, 3, 5 and 7. Each symbol L represents one leaf.
Mentions: To mimic infection via a possible natural route, the unwounded roots of tomato plantlets were immersed in media inoculated with 1 × 107 cfu of bacteria. Only the roots were in contact with the inoculum. Tomato plantlets infected via the roots by B. thailandensis showed progressive symptoms such as yellowing of leaves, blackening of the leaf veins, wilting and necrosis whereas uninfected plantlets remained healthy and did not show any disease symptoms throughout the period (Fig 1A-B). Most infected plantlets were dead on day 7. All plantlets were monitored over a period of seven days. Disease was scored daily for every plantlet on an index from 1-5 based on the extent of symptoms presented as described in Methods. The average disease score for a particular day represent the mean disease scores for all the plantlets with the same treatment on that day. As infection progressed over time, the average disease score for B. thailandensis-infected plants increased progressively, reaching a maximum disease score of 5 on day 7 (Fig 1C). In contrast, plantlets infected with E. coli in the same manner via the roots showed a slight progression of average disease scores over time and reached a maximum disease score of 2 on day 7 (Fig 1C), demonstrating that the extensive disease and death seen was specific to B. thailandensis infection and not due to non-specific stress induced by the experimental manipulations.

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