Pseudomonas orientalis F9 Pyoverdine, Safracin, and Phenazine Mutants Remain Effective Antagonists against Erwinia amylovora in Apple Flowers
| Autor: | Michael Schmid, Vera Dreyfuss, Veronika Zengerer, Matthias P. Lutz, Marco Bieri, Tanja Sostizzo, Amanda Santos Kron, Cosima Pelludat, Mitja N. P. Remus-Emsermann |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
transposon mutagenesis
Siderophore siderophore Mutant detached flower assay Flowers Erwinia Applied Microbiology and Biotechnology Microbiology 03 medical and health sciences chemistry.chemical_compound Pseudomonas Environmental Microbiology Erwinia amylovora biocontrol 030304 developmental biology fire blight Plant Diseases 0303 health sciences Pyoverdine Ecology biology 030306 microbiology food and beverages Pseudomonas orientalis biology.organism_classification Isoquinolines cress assay chemistry Malus domestica Biological Control Agents Malus Fire blight Phenazines Transposon mutagenesis Antagonism safracin Oligopeptides Food Science Biotechnology |
| Zdroj: | Applied and Environmental Microbiology |
| ISSN: | 1098-5336 0099-2240 |
| Popis: | Pseudomonas orientalis F9 is an antagonist of the economically important phytopathogen Erwinia amylovora, the causal agent of fire blight in pomme fruit. On King’s B medium, P. orientalis F9 produces a pyoverdine siderophore and the antibiotic safracin. P. orientalis F9 transposon mutants lacking these factors fail to antagonize E. amylovora, depending on the in vitro assay. On isolated flowers and in soil microcosms, however, pyoverdine, safracin, and phenazine mutants control phytopathogens as clearly as their parental strains. The recently characterized strain Pseudomonas orientalis F9, an isolate from apple flowers in a Swiss orchard, exhibits antagonistic traits against phytopathogens. At high colonization densities, it exhibits phytotoxicity against apple flowers. P. orientalis F9 harbors biosynthesis genes for the siderophore pyoverdine as well as for the antibiotics safracin and phenazine. To elucidate the role of the three compounds in biocontrol, we screened a large random knockout library of P. orientalis F9 strains for lack of pyoverdine production or in vitro antagonism. Transposon mutants that lacked the ability for fluorescence carried transposons in pyoverdine production genes. Mutants unable to antagonize Erwinia amylovora in an in vitro double-layer assay carried transposon insertions in the safracin gene cluster. As no phenazine transposon mutant could be identified using the chosen selection criteria, we constructed a site-directed deletion mutant. Pyoverdine-, safracin-, and phenazine mutants were tested for their abilities to counteract the fire blight pathogen Erwinia amylovora ex vivo on apple flowers or the soilborne pathogen Pythium ultimum in vivo in a soil microcosm. In contrast to some in vitro assays, ex vivo and in vivo assays did not reveal significant differences between parental and mutant strains in their antagonistic activities. This suggests that, ex vivo and in vivo, other factors, such as competition for resources or space, are more important than the tested antibiotics or pyoverdine for successful antagonism of P. orientalis F9 against phytopathogens in the performed assays. IMPORTANCE Pseudomonas orientalis F9 is an antagonist of the economically important phytopathogen Erwinia amylovora, the causal agent of fire blight in pomme fruit. On King’s B medium, P. orientalis F9 produces a pyoverdine siderophore and the antibiotic safracin. P. orientalis F9 transposon mutants lacking these factors fail to antagonize E. amylovora, depending on the in vitro assay. On isolated flowers and in soil microcosms, however, pyoverdine, safracin, and phenazine mutants control phytopathogens as clearly as their parental strains. |
| Databáze: | OpenAIRE |
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