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The plant – arbuscular mycorrhizal fungi – bacteria – pathogen system

multifunctional role of AMF spore-associated bacteria

Bharadwaj, Dharam Parkash (2007). The plant – arbuscular mycorrhizal fungi – bacteria – pathogen system. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2007:90
ISBN 978-91-576-7389-3
[Doctoral thesis]

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The aim of this study was to determine the role of the bacteria associated with arbuscular mycorrhizal (AM) fungi in the interactions between AM fungi, plant hosts and pathogens. Mycorrhizal traits were studied in a potato host using field rhizosphere soils of 12 different plant species as inoculum. High colonisation was found with soil of Festuca ovina and Leucanthemum vulgare, which contained two dominant AMF species (Glomus mosseae and G. intraradices). Bacteria associated with spores of AM fungi (AMB) were isolated from these two AM fungal species with either of the two plant species as hosts. Identification based on fatty acid methyl esters profile analysis revealed high diversity and specific occurrence of certain taxa with either of the two AMF. Some AMB were strongly antagonistic against Rhizoctonia solani in in vitro studies and most of them were spore type-dependent and originated from G. intraradices spores. Occurrence of AMB taxa was also plant host-dependent but antagonism was not. The specificity of AMB to AMF could be due to production of specific exudates, since the results showed that exudates collected from either G. intraradices or AMB stimulated growth of the other organism in a two-compartment plate system, and that concentrations of certain compounds changed several-fold. Certain AMB (Pseudomonas sp. and Stenotrophomonas sp.) showed strong multifunctional effects, i.e. stimulated AMF colonisation of potato roots in outdoor and greenhouse studies, stimulated potato growth in vitro and demonstrated antagonism against several fungal and bacterial plant pathogens. Three AMB from these two genera grown in the presence of exudates of G. intraradices resulted in enhanced antagonistic effects. Production of extracellular enzymes and bioactive compounds varied among the AMB species, suggesting different mechanisms for their multifunctional effects. By using F. ovina inoculated with G. intraradices as a cover crop, it should be possible to enhance the occurrence of strongly pathogen-antagonistic AMB. The association of multifunctional AMB with AMF spores provides evidence that bacteria are involved in the beneficial effects of AM fungi on plants.

Authors/Creators:Bharadwaj, Dharam Parkash
Title:The plant – arbuscular mycorrhizal fungi – bacteria – pathogen system
Subtitle:multifunctional role of AMF spore-associated bacteria
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2007
Number of Pages:45
ALLI. Bharadwaj, D.P., Lundquist, P-O. & Alström, S. 2007. Impact of plant species grown as monocultures on sporulation and root colonization by native arbuscular mycorrhizal fungi in potato. Applied Soil Ecology 35, 213-225. II. Bharadwaj, D.P., Lundquist, P-O., Persson, P. & Alström, S. Cultivable bacteria associated with arbuscular mycorrhizal fungal spores: evidence for specificity. (Submitted manuscript) III. Bharadwaj, D.P., Lundquist, P-O. & Alström, S. Arbuscular mycorrhizal fungal spore-associated bacteria affects mycorrhizal colonization, plant growth and potato pathogens. (Submitted manuscript) IV. Bharadwaj, D.P., Lundquist, P-O. & Alström, S. Interactions between Glomus intraradices, arbuscular mycorrhizal spore-associated bacteria and potato pathogens under in vitro conditions. (Manuscript)
Place of Publication:Uppsala
ISBN for printed version:978-91-576-7389-3
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:vesicular arbuscular mycorrhizae, fungi, bacteria, pathogens, antagonism, solanum tuberosum, festuca ovina, glomus mosseae, glomus intraradices
Keywords:antagonism, arbuscular mycorrhizal fungi, diversity, Festuca ovina, Glomus, Leucanthemum vulgare, pathogens, potato, specificity, spore-associated bacteria
Permanent URL:
ID Code:1532
Department:(NL, NJ) > Dept. of Forest Mycology and Plant Pathology
(S) > Dept. of Forest Mycology and Plant Pathology
Deposited By: Dharam Parkasah Bharadwaj
Deposited On:06 Sep 2007 00:00
Metadata Last Modified:02 Dec 2014 10:12

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