Are there benefits of simultaneous root colonization by different arbuscular mycorrhizal fungi (original) (raw)

Mycorrhizal fungal identity and diversity relaxes plant–plant competition

Ecology, 2011

There is a great interest in ecology in understanding the role of soil microbial diversity for plant productivity and coexistence. Recent research has shown increases in species richness of mutualistic soil fungi, the arbuscular mycorrhizal fungi (AMF), to be related to increases in aboveground productivity of plant communities. However, the impact of AMF richness on plant-plant interactions has not been determined. Moreover, it is unknown whether species-rich AMF communities can act as insurance to maintain productivity in a fluctuating environment (e.g., upon changing soil conditions).

Influence of plant species, mycorrhizal inoculant, and soil phosphorus level on arbuscular mycorrhizal communities in onion and carrot roots

Frontiers in Plant Science, 2024

Arbuscular mycorrhizal fungi (AMF) are ancient and ecologically important symbionts that colonize plant roots. These symbionts assist in the uptake of water and nutrients, particularly phosphorus, from the soil. This important role has led to the development of AMF inoculants for use as biofertilizers in agriculture. Commercial mycorrhizal inoculants are increasingly popular to produce onion and carrot, but their specific effects on native mycorrhizal communities under field conditions are not known. Furthermore, adequate availability of nutrients in soils, specifically phosphorus, can reduce the diversity and abundance of AMF communities in the roots. The type of crop grown can also influence the composition of AMF communities colonizing the plant roots. This study aimed to investigate how AMF inoculants, soil phosphorus levels, and plant species influence the diversity of AMF communities that colonize the roots of onion and carrot plants. Field trials were conducted on high organic matter (muck) soil in the Holland Marsh, Ontario, Canada. The treatments included AMF-coated seeds (three to five propagules of Rhizophagus irregularis per seed) and non-treated onion and carrot seeds grown in soil with low (~46 ppm) and high (~78 ppm) phosphorus levels. The mycorrhizal communities colonizing the onion and carrot roots were identified by Illumina sequencing. Five genera, Diversispora, Claroideoglomus, Funneliformis, Rhizophagus, and Glomus, were identified in roots of both plant species. AMF communities colonizing carrot roots were more diverse and richer than those colonizing onion roots. Diversispora and Funneliformis had a 1.3-fold and 2.9-fold greater abundance, respectively, in onion roots compared to carrots. Claroideoglomus was 1.4-fold more abundant in carrot roots than in onions. Inoculation with R. irregularis increased the abundance and richness of Rhizophagus in AMF communities of onion roots but not in carrot roots. The soil phosphorus level had no effect on the richness and diversity of AMF in the roots of either crop. In summary, AMF inoculant and soil phosphorus levels influenced the composition of AMF communities colonizing the roots of onion and carrot plants, but the effects varied between plant species.

Different Arbuscular Mycorrhizal Fungal Species Are Potential Determinants of Plant Community Structure

Ecology, 1998

Almost all natural plant communities contain arbuscular mycorrhizal fungi (AMF). We hypothesized that the species composition of AMF communities could have the potential to determine plant community structure if the growth response to different AMF species or to communities of AMF species varies among plant species. To test the existence of such a differential response we conducted a pot experiment where each of three plant species, Hieracium pilosella, Bromus erectus, and Festuca ovina were inoculated with each of four AMF species, or with a mixture of these four AMF species, or were uninoculated. The AMF species originated from a calcareous grassland in which the three plant species also coexisted.

Co-Adaptation of Plants and Communities of Arbuscular Mycorrhizal Fungi to Their Soil Conditions

Folia Geobotanica, 2014

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Ignored diversity of arbuscular mycorrhizal fungi in co-occurring mycotrophic and non-mycotrophic plants

Mycorrhiza, 2020

Arbuscular mycorrhizal fungi (AMF) colonization in roots of putative non-mycotrophic species has been known for decades, but our knowledge of AMF community structure in non-mycotrophic plants is limited. Here, we compared AMF species composition and diversity in roots of co-occurring mycotrophic and putative non-mycotrophic herbs in two wetlands. A SSU-ITS-LSU fragment in AMF rDNA was amplified, cloned and sequenced, and used to characterize the AMF community in the roots of 16 putative non-mycotrophic and 18 mycotrophic herbs. The results showed that AMF hyphae and vesicles, but not arbuscules, were commonly present in putative non-mycotrophic plants. A total of 971 AMF sequences were obtained, and these were finally assigned to 28 operational taxonomic units (OTUs). At both sites, AMF taxon richness and Hill number based on Shannon's index in the putative non-mycotrophic herbs were similar to those for mycotrophic plants, but AMF community composition between mycotrophic and non-mycotrophic plants was significantly different. Ten AMF OTUs were uniquely detected in the putative non-mycotrophic species, and two were identified as the AMF indicators in non-mycotrophic plants. These results implied that non-mycotrophic plants may harbor a potential source of AMF diversity previously ignored which should be included in our understanding of diversity, distribution pattern, and ecological significance of root-colonizing AMF. As the first direct comparison of AMF diversity and species composition between mycotrophic and putative non-mycotrophic species in wetlands, our study has important implications for the understanding of AMF distribution patterns.

Imbalanced carbon-for-phosphorus exchange between European arbuscular mycorrhizal fungi and non-native Panicum grasses—A case of dysfunctional symbiosis

Pedobiologia, 2017

Arbuscular mycorrhizal fungi (AMF) are globally widespread root symbionts of the majority of terrestrial plant species, they are present in almost all soils, and show particularly low levels of partner specificity. Usually, they benefit their plant hosts through increased nutrients (especially phosphorus, P) supply, improved growth, stress tolerance and fitness as compared to the non-mycorrhizal plants. In exchange for the symbiotic benefits, plant supplies the fungal partner with carbon (C), constituting symbiotic costs for the plant. Here we tested the effect of four soil treatments, combining removal of indigenous AMF communities and/or supplementation with mineral P to restore plant P nutrition, on plant growth and C fluxes from plant to soil as well as on mineral nutrition of a C 3 and a congeneric C 4 grass species. Contrary to all expectations, both plant species showed lower P and nitrogen contents, and grew smaller, though allocated more C belowground, when supplied with AMFcontaining full soil inoculum as compared to AMF-free inoculum. Our results indicate possible incompatibility of symbiotic partners of different geographic origin (European AMF and tropical/subtropical grasses from Africa/ Asia), leading to apparent parasitism of the plants by the AMF communities in terms of both growth and nutritional responses. Most likely, downregulation of the direct (root) P uptake pathway by the plants in response to mycorrhiza formation over-compensated the symbiotic (indirect) P acquisition via mycorrhizal hyphae. The observed effects could also have been caused (or contributed to) by the relatively young age of the experimental plants, and different composition of microbial communities in the two inoculant (containing or not the AMF).

Inoculation effects on root-colonizing arbuscular mycorrhizal fungal communities spread beyond directly inoculated plants

PLOS ONE

Inoculation with arbuscular mycorrhizal fungi (AMF) may improve plant performance at disturbed sites, but inoculation may also suppress root colonization by native AMF and decrease the diversity of the root-colonizing AMF community. This has been shown for the roots of directly inoculated plants, but little is known about the stability of inoculation effects, and to which degree the inoculant and the inoculation-induced changes in AMF community composition spread into newly emerging seedlings that were not in direct contact with the introduced propagules. We addressed this topic in a greenhouse experiment based on the soil and native AMF community of a post-mining site. Plants were cultivated in compartmented pots with substrate containing the native AMF community, where AMF extraradical mycelium radiating from directly inoculated plants was allowed to inoculate neighboring plants. The abundances of the inoculated isolate and of native AMF taxa were monitored in the roots of the directly inoculated plants and the neighboring plants by quantitative realtime PCR. As expected, inoculation suppressed root colonization of the directly inoculated plants by other AMF taxa of the native AMF community and also by native genotypes of the same species as used for inoculation. In the neighboring plants, high abundance of the inoculant and the suppression of native AMF were maintained. Thus, we demonstrate that inoculation effects on native AMF propagate into plants that were not in direct contact with the introduced inoculum, and are therefore likely to persist at the site of inoculation.

Arbuscular mycorrhizal fungi pre-inoculant identity determines community composition in roots

2009

Pre-inoculation of seedlings with commercial, typically non-indigenous, AMF inoculants is common practice in horticultural and land reclamation industries. How these practices influence AMF community composition in pre-inoculated seedlings after they are planted in soil containing a resident AMF community is almost completely unknown. However, there may be important implications regarding success of horticultural practices, as well as unexpected ecological consequences.

Native arbuscular mycorrhizal fungal communities differentially influence the seedling performance of rare and common Pulsatilla species

Functional Ecology, 2004

1. An experiment was carried out to determine whether the community composition of root-colonizing arbuscular mycorrhizal fungi (AMF) influences the growth and nutrient status of two congeneric Pulsatilla species, one rare and one common in Estonia. We hypothesized that: (i) establishment and growth of plants is influenced by the composition of native AMF communities; (ii) growth of congeneric plant species with different abundances differs due to their response to specific AMF communities; and (iii) distribution of a plant species may depend on the composition of local root symbiotic AMF communities. 2. Rare Pulsatilla patens and common Pulsatilla pratensis were grown in pots, under homogeneous soil nutrient and microbial community conditions, containing either one from two (grassland and forest sites) of natural AMF soil inocula, or no AMF. 3. Lower establishment was observed in the non-mycorrhizal soil compared to AMF inoculated soils. Plant biomass, phosphorus concentration and root AMF colonization of both species were higher, and nitrogen concentration lower, in grassland as opposed to forest inoculum. 4. The common species displayed more vigorous growth than the rare counterpart in the presence of grassland inoculum. Conversely, slightly better growth of a rare species was recorded in the forest inoculum, in which plant biomass was an order of magnitude lower compared to the grassland inoculum. 5. As Pulsatilla spp. roots hosted site-characteristic AMF small-subunit rDNA sequence groupings, we suggest that the presence of AM fungi that are more beneficial for the common species may be one factor behind the observed differential distribution and performance of the two plant species.

High functional diversity within species of arbuscular mycorrhizal fungi

New Phytologist, 2004

Species of arbuscular mycorrhizal fungi (AMF) differ markedly in their improvement of plant nutrition and health. However, it is not yet possible to relate the diversity of an AMF community to its functional properties due to the lack of information on the functional diversity at each taxonomic level. This study investigates the inter-and intraspecific functional diversity of four Glomus species in relation to a phylogenetic analysis of large ribosomal subunit (LSU) sequences. •G r owth and P nutrition of cucumber ( Cucumis sativus ) associated with 24 different isolates of AMF were measured in a two-compartment system with a 33 P-labelled root-free soil compartment. • Intraspecific differences were found in plant growth response and the extension of the fungal mycelium into the root-free soil patch whereas length-specific P uptake of the hyphae remained rather constant within each AMF species. Hence, the length-specific P uptake differed according to species, whereas lower phylogenetic levels were required to match functional characteristics such as fungal growth pattern and plant growth promotion. • The large intraspecific diversity observed for mycelium growth and improvement of P uptake means that AMF communities of low species diversity may still contain considerable functional heterogeneity.