title: Potent and specific bactericidal effect of juglone (5-hydroxy-1,4-naphthoquinone) on the fire blight pathogen Erwinia amylovora.
abstract: A screening of plant quinones for inhibiting effects on the bacterial fire blight pathogen Erwinia amylovora was performed. The most active compound, juglone from walnuts, has a potent and specific bactericidal effect on E. amylovora and minimal inhibitory concentrations of only 2.5-10 μM, with stronger effects at lower, but still physiological, pH values. In vitro tests with juglone and inoculated flowers of apple (Malus domestica) showed an efficacy of 67% in preventing infection. In two years of field tests juglone had variable degrees of efficacy ranging from 40 to 82%, seemingly due to environmental conditions. A phytotoxic reaction to juglone, which is known for its allelopathic effect on plants, was restricted to browning of petals; later fruit russeting was not observed. Juglone is a promising candidate for the development of a new environmentally friendly plant protectant to replace the antibiotic streptomycin currently used in fire blight control.
authors.affiliation: Institute of Chemical Engineering, Vienna University of Technology, Vienna, Austria. thilo.fischer@biologie.uni-muenchen.de
authors.forename: Thilo Christopher
authors.initials: TC
authors.lastname: Fischer
authors.forename: Christian
authors.initials: C
authors.lastname: Gosch
authors.forename: Beate
authors.initials: B
authors.lastname: Mirbeth
authors.forename: Markus
authors.initials: M
authors.lastname: Gselmann
authors.forename: Veronika
authors.initials: V
authors.lastname: Thallmair
authors.forename: Karl
authors.initials: K
authors.lastname: Stich
mesh_terms: D016573:Agrochemicals / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004353:Drug Evaluation, Preclinical; D004355:Drug Stability; D044084:Erwinia amylovora / Q000187:drug effects* / Q000472:pathogenicity*; D035264:Flowers / Q000187:drug effects / Q000382:microbiology; D018525:Germination / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D027845:Malus / Q000187:drug effects* / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D009285:Naphthoquinones / Q000494:pharmacology*; D010935:Plant Diseases / Q000382:microbiology / Q000517:prevention & control; D011809:Quinones / Q000737:chemistry / Q000494:pharmacology; D018675:Toxicity Tests / Q000379:methods
chemical_list: D016573:Agrochemicals; D000900:Anti-Bacterial Agents; D009285:Naphthoquinones; D011809:Quinones; C005134:juglone