Evidence for specificity of cultivable bacteria associated with arbuscular mycorrhizal fungal spores

Bharadwaj, Dharam Parkash; Lundquist, Per-Olof; Persson, Paula; Alström, Sadhna

doi:10.1111/j.1574-6941.2008.00515.x

Cited by 38 publications

(23 citation statements)

References 45 publications

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“…Alternatively, the microbial wash may not have established similar non-AMF soil microbial communities among treatments and, as a result, the AMF-associated microbes present in the inocula could have been responsible for the pine growth reduction in the absence of clover. For example, specific bacterial communities are known to associate with the hyphal surface of AMF and these bacterial communities in the hyphosphere differ among AMF species (Bharadwaj et al 2008;Scheublin et al 2010). This could explain the AMF family-wise effects we observed in the absence of clover and suggests that hyphosphere bacterial communities may be a key factor affecting the growth of pine seedlings in our study; perhaps indicating additional roles by which AMF phylogeny could influence interactions among soil organisms.…”

Section: Discussionmentioning

confidence: 46%

Arbuscular mycorrhizal fungal phylogeny-related interactions with a non-host

2011

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Arbuscular mycorrhizal fungi (AMF) form symbiotic relationships with most vascular plants including some gymnosperm species. Although species in the gymnosperm family Pinaceae normally develop ectomycorrhizal associations, AMF hyphae and vesicles, typical of members of the Suborder Glomineae, have been reported in the roots of some Pinaceae species. However, it is not known whether AMF belonging to various species and suborders are able to colonize roots of Pinaceae species and to what extent this influences the performance of Pinaceae seedlings. We tested in each of the Glomaceae, Acaulosporaceae and Gigasporineae AMF families two species for their ability to colonize and affect the growth of Pinus strobus (eastern white pine) in the presence or absence of an AMF host plant (Trifolium pretense-red clover). Glomus intraradices was the only AMF that colonized pine roots, predominantly in the presence of clover, forming intracellular hyphae and vesicles but not arbuscules. Colonization, however, did not relate to increased pine biomass and the overall presence of AMF, regardless of colonization abilities, resulted in a biomass reduction. This effect on pine seedling biomass was explained by the AMF family to which the AMF belonged, indicating that the effects of AMF on the non-host pine may be related to phylogeny. Acaulosporaceae species reduced pine biomass the most whereas, Gigasporineae species had the smallest effect on biomass. These preliminary results suggest that AMF may affect the soil microflora differently among AMF families in previously unsuspected ways with potential consequences for non-AMF host growth.

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Section: Discussionmentioning

confidence: 46%

Arbuscular mycorrhizal fungal phylogeny-related interactions with a non-host

2011

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“…This would be in agreement with the observations made by Toljander et al (2006) on the attachment of fluorescent pseudomonads to extraradical hyphae after establishment of AM symbiotic association. Several other authors also reported association of pseudomonads with hyphae of AMF (Bianciotto et al , 1996; Roesti et al , 2005; Bharadwaj et al , 2008; Pivato et al , 2008).…”

Section: Discussionmentioning

confidence: 90%

Fluorescent pseudomonads harboring type III secretion genes are enriched in the mycorrhizosphere of Medicago truncatula

Viollet

Corberand

Mougel

et al. 2011

FEMS Microbiology Ecology

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Type III secretion systems (T3SSs) of Gram-negative bacteria mediate direct interactions with eukaryotic cells. Pseudomonas spp. harboring T3SS genes (T3SS+) were previously shown to be more abundant in the rhizosphere than in bulk soil. To discriminate the contribution of roots and associated arbuscular mycorrhizal fungi (AMF) on the enrichment of T3SS+ fluorescent pseudomonads in the rhizosphere of Medicago truncatula, their frequency was assessed among pseudomonads isolated from mycorrhizal and nonmycorrhizal roots and from bulk soil. T3SS genes were identified by PCR targeting a conserved hrcRST DNA fragment. Polymorphism of hrcRST in T3SS+ isolates was assessed by PCR-restriction fragment length polymorphism and sequencing. Genotypic diversity of all pseudomonads isolated, whether or not harboring T3SS, was described by BOX-PCR. T3SS+ pseudomonads were significantly more abundant in mycorrhizal than in nonmycorrhizal roots and in bulk soil, and all were shown to belong to the phylogenetic group of Pseudomonas fluorescens on the basis of 16S rRNA gene identity. Four hrcRST genotypes were described; two only included isolates from mycorrhizal roots. T3SS+ and T3SS- pseudomonads showed different genetic backgrounds as indicated by their different BOX-PCR types. Taken together, these data suggest that T3SSs are implicated in interactions between fluorescent pseudomonads and AM in medic rhizosphere.

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“…AM fungi not only associate with plant roots, but also establish close associations with bacteria in the AM fungus-mycosphere and may include spores (Xavier and Germida, 2003b;Bharadwaj et al, 2008;Cruz and Ishii, 2012) and external mycelia (Mansfeld-Giese et al, 2002). Mycorrhiza-associated bacteria seem to be thriving from AM fungal exudates (Toljander et al, 2007).…”

Section: The Mycorrhizosphere Microbiomementioning

confidence: 99%

Biotic interactions in the rhizosphere in relation to plant and soil nutrient dynamics

Larsen¹,

Jaramillo-López²,

Nájera-Rincón

et al. 2015

J. Soil Sci. Plant Nutr.

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The rhizosphere is the interface between roots and the soil where nutrient absorption for plant growth in agroecosystems is facilitated. An abundant and diverse rhizosphere biome is involved in biogeochemical processes, including bacteria, fungi and soil fauna, driving soil C, N and P dynamics. Plant carbon photosynthates allocated to the root and rhizosphere are priming microbial activities important for plant nutrition such as organic matter decomposition, P solubilization, N fixation, mycorrhizal nutrient transport and biocontrol of root pests. While substantial information is available on the role of individual groups of the rhizosphere microbiome in biogeochemical processes, less attention has been given to the interactions between different beneficial rhizosphere microorganisms. Also, interactions between soil fauna and rhizosphere microorganisms still remain relatively unexplored. In order to improve our knowledge on the role of the rhizosphere in C, N and P biogeochemical processes a more holistic and functional approach is required. In this review, state of the art information on the role of biotic interactions in the rhizosphere on C, N and P biogeochemical processes relevant for plant nutrition in agroecosystems is presented.

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Evidence for specificity of cultivable bacteria associated with arbuscular mycorrhizal fungal spores

Cited by 38 publications

References 45 publications

Arbuscular mycorrhizal fungal phylogeny-related interactions with a non-host

Arbuscular mycorrhizal fungal phylogeny-related interactions with a non-host

Fluorescent pseudomonads harboring type III secretion genes are enriched in the mycorrhizosphere of Medicago truncatula

Biotic interactions in the rhizosphere in relation to plant and soil nutrient dynamics

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