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Duckweed (Lemna minor) as a model plant system for the study of human microbial pathogenesis.

Zhang Y, Hu Y, Yang B, Ma F, Lu P, Li L, Wan C, Rayner S, Chen S - PLoS ONE (2010)

Bottom Line: RN4220, a virulent strain of S. aureus, caused severe toxicity to duckweed while an avirulent strain showed little effect.Using this system for antimicrobial chemical selection, green tea polyphenols exhibited inhibitory activity against S. aureus virulence.Our results demonstrate that duckweed can be used as a fast, inexpensive and reproducible model plant system for the study of host-pathogen interactions, could serve as an alternative choice for the study of some virulence factors, and could also potentially be used in large-scale screening for the discovery of antimicrobial chemicals.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, the Chinese Academy of Sciences, Wuhan, China.

ABSTRACT

Background: Plant infection models provide certain advantages over animal models in the study of pathogenesis. However, current plant models face some limitations, e.g., plant and pathogen cannot co-culture in a contained environment. Development of such a plant model is needed to better illustrate host-pathogen interactions.

Methodology/principal findings: We describe a novel model plant system for the study of human pathogenic bacterial infection on a large scale. This system was initiated by co-cultivation of axenic duckweed (Lemna minor) plants with pathogenic bacteria in 24-well polystyrene cell culture plate. Pathogenesis of bacteria to duckweed was demonstrated with Pseudomonas aeruginosa and Staphylococcus aureus as two model pathogens. P. aeruginosa PAO1 caused severe detriment to duckweed as judged from inhibition to frond multiplication and chlorophyll formation. Using a GFP-marked PAO1 strain, we demonstrated that bacteria colonized on both fronds and roots and formed biofilms. Virulence of PAO1 to duckweed was attenuated in its quorum sensing (QS) mutants and in recombinant strains overexpressing the QS quenching enzymes. RN4220, a virulent strain of S. aureus, caused severe toxicity to duckweed while an avirulent strain showed little effect. Using this system for antimicrobial chemical selection, green tea polyphenols exhibited inhibitory activity against S. aureus virulence. This system was further confirmed to be effective as a pathogenesis model using a number of pathogenic bacterial species.

Conclusions/significance: Our results demonstrate that duckweed can be used as a fast, inexpensive and reproducible model plant system for the study of host-pathogen interactions, could serve as an alternative choice for the study of some virulence factors, and could also potentially be used in large-scale screening for the discovery of antimicrobial chemicals.

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Inoculation of different pathogenic bacterial strains on duckweed growth and chlorophyll concentration.Fresh weight and chlorophyll concentration were quantified 5 d after co-cultivation of 100 µl bacterial cultures with duckweed. Please refer to Table 1 for detailed information of the numbers representing the bacterial species. * P<0.05.
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pone-0013527-g007: Inoculation of different pathogenic bacterial strains on duckweed growth and chlorophyll concentration.Fresh weight and chlorophyll concentration were quantified 5 d after co-cultivation of 100 µl bacterial cultures with duckweed. Please refer to Table 1 for detailed information of the numbers representing the bacterial species. * P<0.05.

Mentions: We have demonstrated the effectiveness of the duckweed-pathogen system using P. aeruginosa and S. aureus as two model human pathogenic bacteria. To test if other important human pathogenic bacteria also induce pathogenicity to duckweed, a number of bacterial species representing different pathogenic backgrounds were chosen and tested. As shown in Figure 7, the severity of the symptoms varied with bacterial strain. For example, unlike the E. coli DH5α negative control, addition of E. coli ATCC 25922 and EHEC O157:H7 produced severe toxicity in duckweed, as demonstrated by complete growth inhibition and bleaching of the fronds (picture not shown). Similarly, addition of clinical isolates of S. Typhimurium and S. Typhi completely killed duckweed in one day, while strains of Shigella dysenteriae, Y. pseudotuberculosis, Y. enterocolitica, and V. parahaemolyticus showed almost no virulence to duckweed (Figure 7). In conclusion, the duckweed system is suitable for screening the virulence of large numbers of different bacterial strains in a short time.


Duckweed (Lemna minor) as a model plant system for the study of human microbial pathogenesis.

Zhang Y, Hu Y, Yang B, Ma F, Lu P, Li L, Wan C, Rayner S, Chen S - PLoS ONE (2010)

Inoculation of different pathogenic bacterial strains on duckweed growth and chlorophyll concentration.Fresh weight and chlorophyll concentration were quantified 5 d after co-cultivation of 100 µl bacterial cultures with duckweed. Please refer to Table 1 for detailed information of the numbers representing the bacterial species. * P<0.05.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2963604&req=5

pone-0013527-g007: Inoculation of different pathogenic bacterial strains on duckweed growth and chlorophyll concentration.Fresh weight and chlorophyll concentration were quantified 5 d after co-cultivation of 100 µl bacterial cultures with duckweed. Please refer to Table 1 for detailed information of the numbers representing the bacterial species. * P<0.05.
Mentions: We have demonstrated the effectiveness of the duckweed-pathogen system using P. aeruginosa and S. aureus as two model human pathogenic bacteria. To test if other important human pathogenic bacteria also induce pathogenicity to duckweed, a number of bacterial species representing different pathogenic backgrounds were chosen and tested. As shown in Figure 7, the severity of the symptoms varied with bacterial strain. For example, unlike the E. coli DH5α negative control, addition of E. coli ATCC 25922 and EHEC O157:H7 produced severe toxicity in duckweed, as demonstrated by complete growth inhibition and bleaching of the fronds (picture not shown). Similarly, addition of clinical isolates of S. Typhimurium and S. Typhi completely killed duckweed in one day, while strains of Shigella dysenteriae, Y. pseudotuberculosis, Y. enterocolitica, and V. parahaemolyticus showed almost no virulence to duckweed (Figure 7). In conclusion, the duckweed system is suitable for screening the virulence of large numbers of different bacterial strains in a short time.

Bottom Line: RN4220, a virulent strain of S. aureus, caused severe toxicity to duckweed while an avirulent strain showed little effect.Using this system for antimicrobial chemical selection, green tea polyphenols exhibited inhibitory activity against S. aureus virulence.Our results demonstrate that duckweed can be used as a fast, inexpensive and reproducible model plant system for the study of host-pathogen interactions, could serve as an alternative choice for the study of some virulence factors, and could also potentially be used in large-scale screening for the discovery of antimicrobial chemicals.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Virology, Wuhan Institute of Virology, the Chinese Academy of Sciences, Wuhan, China.

ABSTRACT

Background: Plant infection models provide certain advantages over animal models in the study of pathogenesis. However, current plant models face some limitations, e.g., plant and pathogen cannot co-culture in a contained environment. Development of such a plant model is needed to better illustrate host-pathogen interactions.

Methodology/principal findings: We describe a novel model plant system for the study of human pathogenic bacterial infection on a large scale. This system was initiated by co-cultivation of axenic duckweed (Lemna minor) plants with pathogenic bacteria in 24-well polystyrene cell culture plate. Pathogenesis of bacteria to duckweed was demonstrated with Pseudomonas aeruginosa and Staphylococcus aureus as two model pathogens. P. aeruginosa PAO1 caused severe detriment to duckweed as judged from inhibition to frond multiplication and chlorophyll formation. Using a GFP-marked PAO1 strain, we demonstrated that bacteria colonized on both fronds and roots and formed biofilms. Virulence of PAO1 to duckweed was attenuated in its quorum sensing (QS) mutants and in recombinant strains overexpressing the QS quenching enzymes. RN4220, a virulent strain of S. aureus, caused severe toxicity to duckweed while an avirulent strain showed little effect. Using this system for antimicrobial chemical selection, green tea polyphenols exhibited inhibitory activity against S. aureus virulence. This system was further confirmed to be effective as a pathogenesis model using a number of pathogenic bacterial species.

Conclusions/significance: Our results demonstrate that duckweed can be used as a fast, inexpensive and reproducible model plant system for the study of host-pathogen interactions, could serve as an alternative choice for the study of some virulence factors, and could also potentially be used in large-scale screening for the discovery of antimicrobial chemicals.

Show MeSH
Related in: MedlinePlus