Pseudomonas orientalis F9: A Potent Antagonist against Phytopathogens with Phytotoxic Effect in the Apple Flower

Zengerer, Veronika; Schmid, Michael; Bieri, Marco; Müller, Denise C.; Remus-Emsermann, Mitja N. P.; Ahrens, Christian H.; Pelludat, Cosima

doi:10.3389/fmicb.2018.00145

Cited by 33 publications

(36 citation statements)

References 71 publications

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“…Therefore, the metabolite profile, mainly the extracellular metabolites, produced by antagonistic isolates determined the inhibitory effect in the dual culture plating assay. Bacterial genera Bacillus and Pseudomonas and fungal genera Biscogniauxia , Chaetomium , Epicoccum and Penicillium identified in this study are important source of potential biocontrol agents, as species of them have been reported to have biocontrol activity (Ferreira et al ; Soytong et al ; Larena et al ; Rančić et al ; Silva‐Hughes et al ; Kurniawan et al ; Zengerer et al ).…”

Section: Discussionmentioning

confidence: 82%

Apple endophyte community is shaped by tissue type, cultivar and site and has members with biocontrol potential againstNeonectria ditissima

2020

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Aims This research aimed to identify factors influencing endophyte community structure in apple shoots and the bioactivity of cultured representatives against the fungal pathogen Neonectria ditissima. Methods and Results The endophyte community in leaves and stems of the apple cultivars ‘Royal Gala’ and ‘Braeburn’ were analysed by a cultivation‐independent method (PCR‐DGGE) which showed that tissue type, cultivar and site were determinant factors, with the endophyte taxa in ‘Royal Gala’ more variable than that in ‘Braeburn’, with leaf endophyte communities typically differing from stems in both cultivars. Seasonal (spring vs autumn) and regional (Nelson vs Hawke’s Bay) variations were not obvious in woody stems. A collection of 783 bacterial and 87 fungal endophytes were recovered from leaves and stems of ‘Royal Gala’, ‘Braeburn’, ‘Scilate’ and/or ‘Scifresh’ from Nelson (nine sites) and Hawke’s Bay (five sites) in spring and from Nelson (three sites) in autumn. A dual culture plating assay was used to test their ability to inhibit the mycelial growth of N. ditissima. Thirteen bacterial (mean of percent inhibition ≥20%) and 17 fungal isolates were antagonistic towards N. ditissima. These isolates belonged to the bacterial genera Bacillus and Pseudomonas, and fungal genera Chaetomium, Epicoccum, Biscogniauxia, Penicillium, Diaporthe, Phlyctema and two unidentified fungal isolates. Conclusions Endophyte communities in apple shoots were determined by tissue type, cultivar and site. Endophytic bacterial and fungal isolates inhibiting N. ditissima growth in vitro were found. Significance and Impact of the Study These results provided new evidence of factors influencing apple endophyte community in New Zealand. Endophytes with potential to reduce N. ditissima infection were identified, with the potential to be developed into a biocontrol strategy for European canker.

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Section: Discussionmentioning

confidence: 82%

Apple endophyte community is shaped by tissue type, cultivar and site and has members with biocontrol potential againstNeonectria ditissima

2020

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“…Indeed, when tested in the cress assay F9 revealed an antagonistic activity against the 82 soil-borne pathogen Pythium ultimum (1). Safracin belongs to the 83 tetrahydroisoquinoline (THIQ) alkaloids, known for their broad-spectrum antibacterial 84 activities (9) and especially strong antitumor activities.…”

Section: Introductionmentioning

confidence: 99%

“…153 However, genome analysis of F9 failed to identify additional secondary siderophores 154 (yersiniabactin, pyochelin, achromobactine, PDTC, thioquinolobactin). 158 A previous study demonstrated that P. orientalis F9 is capable of inhibiting the growth 159 of bacterial phytopathogens and antagonists in vitro (1). Strains E. amylovora Rif , 160 E. amylovora antagonist Pantoea vagans C9-1, P. syringae pv.…”

Section: Introductionmentioning

confidence: 99%

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Pseudomonas orientalis F9 Pyoverdine, Safracin, and Phenazine Mutants Remain Effective Antagonists against Erwinia amylovora in Apple Flowers

Kron

Zengerer

Bieri

et al. 2020

Appl Environ Microbiol

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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.

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“…Due to the microbiota's diversity and complexity, it is not surprising that the traditional view of host-microbe interactions focussing on plant pathogens, nitrogen-fixing rhizobacteria, and phosphate-mobilizing mycorrhizal fungi, has recently shifted to a holistic view considering the plant and its associated microbiota as a metaorganism or holobiont [4][5][6] . It is widely recognised that members of the microbiota assist in nutrient uptake, promote growth, and protect against biotic and abiotic stresses [7][8][9][10][11][12][13][14] . To harness these positive impacts of plant-associated microbiota, the use of synthetic microbiota has been proposed [15][16][17] .…”

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confidence: 99%

Litterbox - A gnotobiotic zeolite-clay system to investigate Arabidopsis-microbe interactions

Miebach

Schlechter

Clemens

et al. 2020

Preprint

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Plants are colonised by millions of microorganisms representing thousands of species with varying effects on plant growth and health. The microbial communities found on plants are compositionally consistent and their overall positive effect on the plant is well known. However, the effects of individual microbiota members on plant hosts and vice versa , as well as the underlying mechanisms remain largely unknown. Here, we describe 'Litterbox', a highly controlled system to investigate plant-microbe interactions. Plants were grown gnotobiotically on zeolite-clay, an excellent soil replacement that retains enough moisture to avoid subsequent watering. Plants grown on zeolite phenotypically resemble plants grown under environmental conditions. Further, bacterial densities on leaves in the Litterbox system resembled those in temperate environments. A PDMS sheet was used to cover the zeolite, thereby significantly lowering the bacterial load in the zeolite and rhizosphere. This reduced the likelihood of potential systemic responses in leaves induced by microbial rhizosphere colonisation. We present results of example experiments studying the transcriptional responses of leaves to defined microbiota members and the spatial distribution of bacteria on leaves. We anticipate that this versatile and affordable plant growth system will promote microbiota research and help in elucidating plant-microbe interactions and their underlying mechanisms. Introduction:Plants offer three different habitats to microbes: the endosphere, the rhizosphere, and the phyllosphere. The endosphere encompasses the habitat formed by internal tissues of plants, whereas the rhizosphere and phyllosphere encompass the surfaces of belowground and aboveground plant organs, respectively. Plants host remarkably diverse and complex, yet structured, microbial communities, collectively referred to as the plant microbiota [1][2][3] . Due to the microbiota's diversity and complexity, it is not surprising that the traditional view of host-microbe interactions focussing on plant pathogens, nitrogen-fixing rhizobacteria, and phosphate-mobilizing mycorrhizal fungi, has recently shifted to a holistic view considering the plant and its associated microbiota as a metaorganism or holobiont [4][5][6] . It is widely recognised that members of the microbiota assist in nutrient uptake, promote growth, and protect against biotic and abiotic stresses [7][8][9][10][11][12][13][14] . To harness these positive impacts of plant-associated microbiota, the use of synthetic microbiota has been proposed [15][16][17] . The prospect of using synthetic microbial communities to promote sustainable agriculture is leading to a growing appreciation of plant microbiota research.Generally, plant microbiota research aims to understand 1) plant-microbe and microbe-microbe interactions ranging from the individual microorganism to the microbial community resolution, 2) the underlying molecular mechanisms of these interactions, and 3) their contribution to microbial community structure. Thus far...

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Pseudomonas orientalis F9: A Potent Antagonist against Phytopathogens with Phytotoxic Effect in the Apple Flower

Cited by 33 publications

References 71 publications

Apple endophyte community is shaped by tissue type, cultivar and site and has members with biocontrol potential againstNeonectria ditissima

Apple endophyte community is shaped by tissue type, cultivar and site and has members with biocontrol potential againstNeonectria ditissima

Pseudomonas orientalis F9 Pyoverdine, Safracin, and Phenazine Mutants Remain Effective Antagonists against Erwinia amylovora in Apple Flowers

Litterbox - A gnotobiotic zeolite-clay system to investigate Arabidopsis-microbe interactions

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