Duckweed (Lemna minor) as a Model Plant System for the Study of Human Microbial Pathogenesis

Abstract

BackgroundPlant 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 FindingsWe 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/SignificanceOur 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.

Choosing an Appropriate Infection Model to Study Quorum Sensing Inhibition in Pseudomonas Infections

“…The plant Arabidopsis thaliana was used as a model to study the virulence of a P. aeruginosa clinical isolate and the results indicated that the pathogen employs a similar subset of virulence factors to elicit disease in plants as it does in animals [40]. Lemna minor (duckweed) is widely used as a plant model for studies in plant physiology, genetics, ecology and environmental monitoring [41]. The reasons that make duckweeds a preferred model for such studies are their small size, their ability to rapidly undergo vegetative reproduction thus forming genetically uniform clones, and their high sensitivity to organic and inorganic substances.…”

Using Ecological Knowledge and Molecular Tools to Develop Effective and Safe Biocontrol Strategies

“…Due to the fact that the whole program to investigate toxicology is time-consuming and expensive, alternative test systems should be used, e.g. the Caenorhabditis elegans assay (Zachow et al, 2009) or Duckweed (Lemna minor) as a model plant system for the study of human microbial pathogenesis (Zhang et al, 2010).…”

Water lentils (duckweed) in Jordan irrigation ponds as a natural water bioremediation agent and protein source for broilers

“…Duckweed is also used in Chinese traditional medicine for the treatment of ailments such as respiratory tract infections. Duckweed can be used as a fast-growing, inexpensive, and reproducible model plant system for the study of hostpathogen interactions in human pathogenesis (Zhang et al, 2010). Duckweed has the ability to purify wastewater at a low cost (Brix, 1995;Brix, 1997) by removing nutrients from water, and is used in water treatment as a natural bioremediation agent (Ansal et al, 2010).…”