Description: | There have been increased concerns of leafy vegetable contamination by human pathogens and food safety due to outbreaks associated with consumption of fresh produce. In this study, we assessed defense responses induced by the fully pathogenic bacteria Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium SL1344 in both Arabidopsis thaliana. Unlike SL1344, O157:H7 induces strong plant immunity at both pre-invasion and post-invasion steps of infection. For instance, O157:H7 triggers stomatal closure even under high relative humidity (RH); an environmental condition that generally weakens plant defenses against bacteria in the field and laboratory conditions. SL1344 instead induces a transient stomatal immunity. We also observed that O157:H7 modulates more components of innate immunity, i.e. genes and signaling pathways, as compared to SL1344. These results suggest that plants may recognize and respond to some human pathogens more effectively than others. Furthermore, stomatal immunity can diminish the penetration of human pathogens through the leaf epidermis resulting in low bacterial titers in the plant apoplast, which suggest that additional control measures can be employed to prevent food contamination. The understanding of how plant responses can diminish bacterial contamination is paramount in preventing outbreaks and improving the safety of food's supplies. |