title: Ingress of Salmonella enterica Typhimurium into tomato leaves through hydathodes.
abstract: Internal contamination of Salmonella in plants is attracting increasing attention for food safety reasons. In this study, three different tomato cultivars "Florida Lanai", "Crown Jewel", "Ailsa Craig" and the transgenic line Sp5 of "Ailsa Craig" were inoculated with 1 µl GFP-labeled Salmonella Typhimurium through guttation droplets at concentrations of 10(9) or 10(7) CFU/ml. Survival of Salmonella on/in tomato leaves was detected by both direct plating and enrichment methods. Salmonella cells survived best on/in the inoculated leaves of cultivar "Ailsa Craig" and decreased fastest on/in "Florida Lanai" leaves. Increased guttation in the abscisic acid over-expressing Sp5 plants may have facilitated the entrance of Salmonella into leaves and the colonization on the surface of tomato leaves. Internalization of Salmonella Typhimurium in tomato leaves through guttation drop inoculation was confirmed by confocal laser microscopy. For the first time, convincing evidence is presented that S. enterica can enter tomato leaves through hydathodes and move into the vascular system, which may result in the internal translocation of the bacteria inside plants.
authors: Emerging Pathogens Institute and Department of Plant Pathology, University of Florida, Gainesville, Florida, United States of America. ggu@ufl.edu
authors: Ganyu
authors: G
authors: Gu
authors: Juan M
authors: JM
authors: Cevallos-Cevallos
authors: Ariena H C
authors: AH
authors: van Bruggen
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism; D058491:Bacterial Load; D005516:Food Microbiology; D049452:Green Fluorescent Proteins / Q000235:genetics; D054884:Host-Pathogen Interactions / Q000235:genetics; D018551:Solanum lycopersicum / Q000235:genetics / Q000382:microbiology* / Q000502:physiology; D018613:Microscopy, Confocal; D019441:Plant Epidermis / Q000235:genetics / Q000382:microbiology; D010937:Plant Growth Regulators / Q000502:physiology; D018515:Plant Leaves / Q000235:genetics / Q000382:microbiology*; D030821:Plants, Genetically Modified; D012486:Salmonella typhimurium / Q000235:genetics* / Q000472:pathogenicity* / Q000502:physiology; D013045:Species Specificity
chemical_list: D010937:Plant Growth Regulators; D049452:Green Fluorescent Proteins; D000040:Abscisic Acid