Localization of Associative Cyanobacteria on the Roots of Epiphytic Orchids
ABSTRACT This work is the first study of the localization of phototrophic microorganisms in the rhizoplane and velamen of epiphytic orchids, namely, on the aerial and substrate roots of Acampe papillosa and Dendrobium moschatum and on the aerial roots of Phalaenopsis amabilis and Dendrobium phalaenopsis. The composition of the bacterial community on the plant roots depended on the conditions of plant growth. Under conditions simulating the climate of moist tropical forests, the aerial roots proved to be populated with phototrophic microorganisms, among which cyanobacteria predominated. Interlaced fungal hyphae and filamentous cyanobacteria formed a sheath on the surface of the aerial roots. The nitrogen-fixing capacity of the sheath of the aerial roots was studied on the example of P. amabilis.
- Botanical Gazette 01/1957; 119(2).
Article: Microbiota of the Orchid Rhizoplane[show abstract] [hide abstract]
ABSTRACT: Six bacterial strains isolated from the underground roots of the terrestrial orchid Calanthe vestitavar. rubro-oculatawere found to belong to the genera Arthrobacter, Bacillus, Mycobacterium, and Pseudomonas.Strains isolated from the aerial roots of the epiphytic orchid Dendrobium moschatumwere classified into the genera Bacillus, Curtobacterium, Flavobacterium, Nocardia, Pseudomonas, Rhodococcus, and Xanthomonas.The rhizoplane of the terrestrial orchid was also populated by cyanobacteria of the genera Nostocand Oscillatoria, whereas that of the epiphytic orchid was populated by one genus, Nostoc.In orchids occupying different econiches, the spectra of the bacterial genera revealed differed. The microbial complex of the terrestrial orchid rhizoplane differed from that of the surrounding soil.Microbiology 06/2001; 70(4):492-497. · 0.65 Impact Factor
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ABSTRACT: Seven isolates of orchid-associated bacteria (OAB) belonging to five species were tested for their effect on mycorrhiza-assisted germination of the terrestrial orchid Pterostylis vittata. Hormone standards were also tested to evaluate their potential roles in the germination and development of the orchid. Strains of Pseudomonas putida, Xanthomonas maltophilia and Bacillus cereus promoted symbiotic germination, whereas certain strains of P. putida and an Arthrobacter species reduced it. Symbiotic germination was enhanced by IAA, inhibited by gibberellic acid and suppressed by kinetin. Each species of OAB produced IAA, although the conditions of growth affected the production of the auxin. IAA was not produced by the mycorrhizal fungus from P. vittata under the test conditions. Enhancement of symbiotic germination development may have resulted either from the production of IAA by the OAB and/or by the induction of endogenous hormones in the orchid by the metabolites of the bacteria and/or mycorrhizal fungus.Plant and Soil 01/1994; 159(2):291-295. · 2.64 Impact Factor