Colonization strategy of the endophytic plant growth‐promoting strains of Pseudomonas fluorescens and Klebsiella oxytoca on the seeds, seedlings and roots of the epiphytic orchid, Dendrobium nobile Lindl

Aims Orchids form strong mycorrhizal associations, but their interactions with bacteria are poorly understood. We aimed to investigate the distribution of plant growth promoting rhizobacteria (PGPR) at different stages of orchid development and to study if there is any selective specificity in choos...

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Bibliographic Details
Published in:Journal of applied microbiology 2017-07, Vol.123 (1), p.217-232
Main Authors: Pavlova, A.S., Leontieva, M.R., Smirnova, T.A., Kolomeitseva, G.L., Netrusov, A.I., Tsavkelova, E.A.
Format: Article
Language:English
Subjects:
Acetic acid
auxin (indole‐3‐acetic acid)
Bacteria
bacterization of Dendrobium nobile
Colonization
Conservation
Developmental stages
Endophytes
endophytic rhizobacteria
Epiphytes
Expansion
Germination
In vitro methods and tests
Indoleacetic acid
Klebsiella
Media
Microorganisms
Nitrogen
orchid seed germination
Parenchyma
Plant growth
Populations
Promotion
Pseudomonas
Pseudomonas fluorescens
Pseudomonas fluorescens and Klebsiella oxytoca
Rhizoids
Roots
Seed germination
Seedlings
Seeds
Strategy
Tryptophan
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Summary:Aims Orchids form strong mycorrhizal associations, but their interactions with bacteria are poorly understood. We aimed to investigate the distribution of plant growth promoting rhizobacteria (PGPR) at different stages of orchid development and to study if there is any selective specificity in choosing PGPR partners. Methods and Results Colonization patterns of gfp‐tagged Pseudomonas fluorescens and Klebsiella oxytoca were studied on roots, seeds, and seedlings of Dendrobium nobile. Endophytic rhizobacteria rapidly colonized velamen and core parenchyma entering through exodermis and the passage cells, whereas at the early stages, they stayed restricted to the surface and the outer layers of the protocorms and rhizoids. The highest amounts of auxin (indole‐3‐acetic acid) were produced by K. oxytoca and P. fluorescens in the nitrogen‐limiting and NO3‐containing media respectively. Bacterization of D. nobile seeds resulted in promotion of their in vitro germination. The plant showed no selective specificity to the tested strains. Klebsiella oxytoca demonstrated more intense colonization activity and more efficient growth promoting impact under tryptophan supplementation, while P. fluorescens revealed its growth‐promoting capacity without tryptophan. Conclusions Both strategies are regarded as complementary, improving adaptive potentials of the orchid when different microbial populations colonize the plant. Significance and Impact of the Study This study enlarges our knowledge on orchid–microbial interactions, and provides new features on application of the nonorchid PGPR in orchid seed germination and conservation.
ISSN:1364-5072
1365-2672
DOI:10.1111/jam.13481