Influence of surface polysaccharides of Escherichia coli O157:H7 on plant defense response and survival of the human enteric pathogen on Arabidopsis thaliana and lettuce (Lactuca sativa)

摘要

AbstractThis study aimed to determine the influence of bacterial surface polysaccharides (cellulose, colanic acid, and lipopolysaccharide; LPS) on the colonization or survival ofEscherichia coliO157:H7 on plants and the plant defense response. Survival ofE. coliO157:H7 were evaluated onArabidopsis thalianaand romaine lettuce as a model plant and an edible crop (leafy vegetable), respectively. The population of the wild-type strain ofE. coliO157:H7 onArabidopsisplants and lettuce was significantly (P < 0.05) greater compared with the colanic acid-deficient and LPS-truncated mutants on day 1 and day 5 post-inoculation. This result indicates that colanic acid and LPS structures may contribute to the ability of bacterial survival or persistence on plants. The wild-type strain ofE. coliO157:H7 produced approximately twice the amount (P < 0.05) of capsular polysaccharide (CPS) than the colanic acid and LPS-truncated mutants. The significantly lower production of CPS was associated with significantly greater (2-fold) expression of pathogenesis-related gene (PR1) compared with the wild-type and cellulose-deficient mutant (P < 0.05). Collectively, the results of this study may suggest that specific surface polysaccharides ofE. coliO157:H7 differentially induce the plant defense response, consequently affecting the survival of the human pathogen on plants. The survival and persistence ofE. coliO157:H7 was similar onArabidopsisand lettuce regardless of day post-inoculation.Highlights•Surface polysaccharides ofE. coliO157:H7 influenced survival ability on plants.•Colanic acid and LPS contributed to survival/persistence onArabidopsisand lettuce.•Lower expression ofPR1gene by wild-typeE. coliO157:H7 led to greater survival.•Capsular polysaccharide may play important roles in pathogen-plant interactions.•Comparative study betweenArabidopsisand lettuce showed a similar survival trend ofE. coliO157:H7.