Mycorrhizal Communities Research Articles

Low Specificity but Dissimilar Mycorrhizal Communities Associating with Roots May Contribute to the Spatial Pattern of Four Co-Occurring Habenaria (Orchidaceae) Species

Fungi with orchid roots have been increasingly proven to play important roles in orchid growth, spatial distribution, and coexistence of natural communities. Here, we used 454 amplicon pyrosequencing with two different primer combinations to investigate the spatial variations in the community of OMF and endophytic fungi associates within the roots of four co-occurring Habenaria species. The results showed that all investigated Habenaria species were generalists and the different fungi communities may contribute to the spatial separation of the four Habenaria species. Firstly, the fungal OTUs identified in the roots of the four species overlapped but their presence differed amongst species and numerous distinct OMF families were unique to each species. Second, NMDS clustering showed samples clustered together based on associated species and PERMANOVA analyses indicated that fungi communities in the roots differed significantly between the Habenaria species, both for all endophytic fungi communities and for OMF communities. Third, the network structure of epiphytic fungi was highly specialized and modular but demonstrated lowly connected and anti-nested properties. However, it calls for more soil nutrition and soil fungal communities' studies to elucidate the contribution of habitat-specific adaptations in general and mycorrhizal divergence.

Mycobiome of Post-Agricultural Soils 20 Years after Application of Organic Substrates and Planting of Pine Seedlings

A 20-year study of a pine stand on post-agricultural land showed that woody debris in the form of organic matter can be successfully used to restore symbiotic mycorrhizal communities, as is the case with forest soils. Woody substrates restored organic matter in soils altered by long agricultural use and had a positive effect on the composition of mycobiota antagonistic to pathogens, especially to Heterobasidion annosum, the causal agent of the dangerous disease root and stump rot of many forest tree species, including stands of Pinus sylvestris (L.). In a study that started in 2001 in the forest district of Czarne Człuchowskie (northern Poland), the following organic materials were used: wood residues (W), sawdust (S), bark compost (B), and compost applied to the root zone during planting (G). The organic materials were spread in the form of mulch over the entire area during planting. After twenty years, it was found that the substrates used provided suitable growth conditions for mycobiome useful for pines. The addition of organic matter did not change the alpha biodiversity of the soil, but in the long term led to significant changes in the composition of mycobiota (beta biodiversity). The changes in the soil after the addition of organic material naturally accelerated the formation of the forest habitat. A number of fungi evolved that degraded added lignin and cellulose while being antagonists of H. annosum and other pine pathogens. In particular, the well-known hyperpathogens of the genus Trichoderma played an important role by promoting resistance of the soil environment to pathogens. Soil enrichment by bark compost and wood residues increased the relative abundance of Trichoderma more than fourfold.Mycorrhizal fungi became dominant in soil enriched with organic matter. After enriching the soil with bark compost, the relative abundance of Amphinema and Inocybe increased to 5%. The relative abundance of Russula in soil enriched with wood residues and sawdust increased to 9% and 5%, respectively. Mycorrhizal fungi, e.g., of the genus Ąmanita, Rusula, which formed root mycorrhizae, not only increased the root receiving area many times over, but also protected the roots (mechanically and chemically from pathogens). Altogether, the observed positive changes increase the chances that the first generation of pines will survive on the ground.

Assessment of the potential of Vachellia seyal and Prosopis chilensis for the reclamation of saline soil lands in the peanut basin production of Senegal.

Soil properties and microbial activities are indicators that shape plant communities and evolution. We aimed to determine the interdependency between trees, belowground herbaceous plants, soil characteristics, and arbuscular mycorrhizal communities. Vachellia seyal and Prosopis chilensis and their associated herb layers were targeted. Soils sampled beneath the trees and outside the canopies were subjected to physicochemical and microbial characterization. Randomly collected living roots of trees and dominant herbs were checked for arbuscular mycorrhizal colonization. A tree seedlings nursery was conducted using black bags filled with the following substrates: natural soil 100%, soil mixed with leaf tree plants (LTPs) as organic matter at 10%, soil mixed with LTP at 20%, soil mixed with LTP at 30%, and soil mixed with LTP at 50%. As a result, the presence of trees improves both herb richness and diversity. Soil mycorrhizal inoculum potentials are higher beneath V. seyal than P. chilensis and decreased significantly with increasing distance from trees. The soil MIP decreased with increasing organic matter content for both tree species but was more pronounced for P. chilensis. Soil salinity is lower beneath V. seyal and higher under P. chilensis and outside the canopies. Soil fertility parameters such as carbon, nitrogen, and available phosphorus are higher beneath the trees and then decreased as the distance to the trees increases. We conclude that microbial communities, soil properties, and herb richness and diversity increased beneath the trees but decreased with increasing distance from the trees. This effect is tree species-dependent as P. chilensis increased soil salinity and decreased the belowground density of herbs.

Mycorrhizal diversity and community composition in co-occurring Cypripedium species.

Orchids commonly rely on mycorrhizal fungi to obtain the necessary resources for seed germination and growth. Whereas most photosynthetic orchids typically associate with so-called rhizoctonia fungi to complete their life cycle, there is increasing evidence that other fungi may be involved as well and that the mycorrhizal communities associated with orchids may be more diverse. Coexisting orchid species also tend to associate with different fungi to reduce competition for similar resources and to increase long-term population viability. However, few studies have related the mycorrhizal communities in the rhizosphere to communities found in the roots of closely related coexisting orchid species. In this study, we used high-throughput sequencing to investigate the diversity and community composition of orchid mycorrhizal fungi in the roots and the rhizosphere of four Cypripedium species growing in forests in Northeast China. The results showed that the investigated Cypripedium species associated with a wide variety of fungi including members of Tulasnellaceae, Psathyrellaceae, and Herpotrichiellaceae, whereas members of Russulaceae, Cortinariaceae, Thelephoraceae, and Herpotrichiellaceae showed high abundance in rhizosphere soils. The diversity of fungi detected in the rhizosphere soil was much higher than that in the roots. The observed variation in fungal communities in Cypripedium roots was not related to forest site or orchid species. On the other hand, variation in mycorrhizal communities of rhizosphere soil was significantly related to sampling site. These results indicate that orchid mycorrhizal communities in the rhizosphere display considerable variation among sites and that orchids use only a subset of the locally available fungi. Future studies focusing on the fine-scale spatial distribution of orchid mycorrhizal fungi and more detailed assessments of local environmental conditions will provide novel insights into the mechanisms explaining variation of fungal communities in both orchid roots and the rhizosphere.

Arbuscular mycorrhizal fungi potentiate the root system and the quality of goldenberry fruits

The lack of information on the horticultural performance of goldenberry (Physalis peruviana L.) is one of the factors that limits the expansion of the crop. Still, aiming to establish a sustainable management for this culture, inoculation with arbuscular mycorrhizal fungi (AMF) can be adopted. Therefore, the objective of the research was to investigate whether goldenberry plants in the absence and presence of inoculation with AMF differ in terms of horticultural performance. The four treatments studied were the absence (control) and the presence of three inoculants based on AMF (mycorrhizal community, Glomus intraradices and Rhizophagus clarus), arranged in a randomized block design, with five replications. Goldenberry plants produced in substrate enriched with AMF had a more voluminous root system and a greater amount of fine roots. Additionally, the fruits were sweeter and more flavorful when produced by plants inoculated with the mycorrhizal community and with R. clarus. It is concluded that mycorrhization has no effect on fruit production. However, goldenberry plants submitted to mycorrhizal biotechnology enhance the chemical quality of fruits and present a more profuse root system. G. intraradices is most effective in colonizing the roots of the plant host.

Dominant Dendrobium officinale mycorrhizal partners vary among habitats and strongly induce seed germination in vitro

Dendrobium officinale(Orchidaceae) is an endangered epiphytic orchid that has been well studied as a medicinal plant. Although previous studies have shown that various fungal isolates promoteD. officinaleseed germination and seedling developmentin vitro, mycorrhizal associations among its wild populations remain poorly understood. In this study, we identified mycorrhizal fungi associated withD.officinale(36 individuals from six sites) using Sanger sequencing and compared fungal communities among sites and habitats (lithophytic vs. epiphytic individuals). Among the obtained sequences, 76 belonged to orchid mycorrhizal fungi (OMF), among which Tulasnellaceae accounted for 45.8% and Serendipitaceae for 28.1%. The Serendipitaceae operational taxonomic unit (OTU) SE1 was the most dominant partner, accounting for 27.1% of all detected fungal sequences, followed by a Tulasnellaceae OTU, TU27, which accounted for 15.6%. The relative frequencies of Serendipitaceae and Tulasnellaceae differed greatly between lithophytic and epiphytic individuals. Serendipitaceae accounted for 47.3% of the OMF sequences among lithophytes, and Tulasnellaceae for 95.2% among epiphytes. Mycorrhizal community composition also varied among sites. We further conductedin vitrosymbiotic culture from seeds with six fungal isolates. Two Serendipitaceae and two Tulasnellaceae isolates, including SE1 and TU27, significantly promoted seed germination and seedling development. These results indicate thatD.officinaleis mainly associated with Tulasnellaceae and Serendipitaceae as its main fungal partners, which strongly induced seed germination and seedling developmentin vitro, suggesting their association withD.officinalethrough its life cycle.

Mixed conifer-broadleaf trees on arbuscular mycorrhizal and ectomycorrhizal communities in rhizosphere soil of different plantation stands in the temperate zone, Northeast China.

In comparison with ectomycorrhizal (EM) tree species, arbuscular mycorrhizal (AM) trees have different litter quality and nitrogen cycle modes, which may affect mycorrhizal colonization and the community composition and diversity. However, available studies addressing the mycorrhizal fungal colonization rate, diversity and community composition in mixed forest stands composed of AM and EM trees are rare. In the present study, we assessed litter quality, soil physicochemical properties and correlated them with mycorrhizal community characteristics in rhizosphere soils of monoculture and mixture plantation stands of AM tree species (Fraxinus mandschurica Rupr.) and EM tree species (Larix gmelinii Rupr., Picea koraiensis Nakai) in Northeast China. We hypothesized that (1) the effect of mixture pattern on mycorrhizal colonization rate and diversity would change with tree species, (2) the effect of mixture pattern on mycorrhizal community composition would be less pronounced in comparison with that of tree species. We found that mixture did not change AMF colonization rate regardless of mixture identity, whereas mixture and tree species exerted significant effects on EMF colonization rate. For AMF community, both M-AS (Fraxinus mandschurica Rupr. and Picea koraiensis Nakai) and M-AL (Fraxinus mandschurica Rupr. and Larix gmelinii Rupr.) mixtures significantly increased Pielou index and Simpson index, whereas only M-AS significantly increased Sobs. For EMF community, mixture significantly affected examined diversity indices except for Chao1. Mixture significantly shifted AMF and EMF community, and the magnitude was tree species dependent. The dominant genera in AMF and EMF communities in plantation stands were Glomus and Tomentella, respectively. The EnvFit analysis showed that the determinant factors of EMF community are soil moisture, pH, nitrate nitrogen content, dissolved organic nitrogen content, soil organic matter content, soil organic carbon/total nitrogen and litter carbon/total nitrogen. In conclusion, mixed conifer-broadleaf trees significantly changed soil physicochemical properties, litter quality as well as mycorrhizal fungi community diversity and composition.

Degradation of mycorrhizal fungal communities associated with cork oak and understory vegetation by the anthropogenic factors

Abstract The cork oak (Quercus suber L.) forests are ecosystems of high environmental and socioeconomic value in the Mediterranean basin. However, in Algeria, the cork oak forests are highly threatened by repeated fires, overgrazing and the anthropogenic pressure that weaken the ecosystem of cork oak and affect its natural regeneration. This degradation results in an alteration of many ecological components of the cork oak, such as fungal communities in the soil. Thus, the aim of this work is to study the effects of cork oak stand degradation on the diversity of mycorrhizal communities associated with Quercus suber and some of its understory shrubs (Cistus monspeliensis, Lavandula stoechas and Thymus vulgaris) in the forest of Brabtia (northeastern Algeria).For this purpose, two sites were chosen: one degraded by the anthropogenic factors and the other non-degraded one. Moreover, it is suggested that some plants of the understory shrub vegetation of cork oak, such as the cistus, lavender and thyme, prove to be favourable to the juvenile growth of this tree. The results obtained showed that the ectomycorrhizal (EcM) root colonization of cistus was higher compared to that of cork oak in both stations. The estimation of arbuscular mycorrhizal (AM) colonization showed significantly higher levels in the roots of cork oak, cistus, lavender and thyme in the degraded station compared with the non-degraded stations. In contrast, the rhizosphere soils of cork oak and cistus had low number of AM propagules and fungal spores, while under the roots of lavender and thyme, these two parameters were greatly improved with the abundance of the genera Glomus and Gigaspora. These results underline the need to take into account the plant–fungus interactions in the development of restoration strategies of the degraded soils and forest ecosystems.

Bacterial, fungal, and mycorrhizal communities in the soil differ between clearcuts and insect outbreaks in the boreal forest 50 years after disturbance

Soil microorganisms influence the functions and processes of forest ecosystems, and their composition is affected by natural and anthropogenic disturbances. Timber harvesting disturbs boreal soil microbiomes, most notably ectomycorrhizal communities which are reportedly less diverse in the first decade following a clearcut. However, the long-term impact of harvesting on forest soil microorganism communities have rarely been investigated nor compared with natural disturbances. Our objective was to compare the composition and diversity of bacterial, fungal, and mycorrhizal communities between boreal old-growth and nearby 50–year–old stands regenerating after either an insect outbreak or a clearcut. Our main hypothesis was that the nature of the stand–replacing disturbance influences the composition of the soil microbiome, and that the effect is still detectable 50 years later. We collected 90 samples from 30 plots across six forest stands dominated by Abies balsamea. We sequenced the genome regions 16S rRNA v3v4 for bacteria and ITS1 for fungi and we constructed distance matrices to evaluate changes in community composition with permutational analyses of variance. Results show that 10.2 % to 12.4 % of the variability in community composition can be explained by stand type alone for bacteria, fungi, and mycorrhizae. The composition of soil microbiomes did not vary with soil physicochemical properties. Stands regenerating after a clearcut had a greater alpha diversity (H’) of fungi and mycorrhizae than stands regenerating after an insect outbreak, while old–growth stands were intermediate. Our data indicate that soil microbiomes associated with natural disturbance dynamics differ from those of clearcutted stands, although the mechanisms underlying this pattern remain unclear. Therefore, we suggest that forest managers spare the largest possible tracts of unmanaged forests across the harvested landscape, including areas affected by natural disturbances, so that benchmark soil communities remain available for future studies.

Arbuscular mycorrhizal fungi community in soils under desertification and restoration in the Brazilian semiarid

Soil desertification has a significant social, economic, and environmental impact worldwide. Mycorrhizal diversity remains poorly understood in semiarid regions impacted by desertification, especially in Brazilian drylands. More importantly, positive impacts of grazing exclusion on mycorrhizal communities are still incipient. Here, we hypothesized that overgrazing changes the structure of Arbuscular Mycorrhizal Fungi (AMF) community compared to native areas and, grazing exclusion is effective to restore the AMF community. Thus, we analyzed the status of AMF community in soils under desertification (overgrazing) and restoration (twenty-years of grazing exclusion) in the Brazilian semiarid. AMF-spores were extracted via humid decantation methodology, morphologically classified, and alpha diversity metrics were calculated. Soil samples were chemically, and physically characterized and multivariate statistical analyses were applied to verify the impact of soil degradation and restoration on AMF-community. Briefly, native, and restored areas presented higher contents of organic matter, phosphorus, microbial carbon, and β-glucosidase activity. However, degraded soil showed higher Al3+, Na+, and bulk soil density values. The abundance of AMF spores was higher in restored soil, followed by degraded and native vegetation, and Shannon’s diversity index was significantly higher in restored soils, followed by native vegetation. AMF-spores were classified into four families (Gigasporaceae > Acaulosporaceae > Glomeraceae > Ambisporaceae). Ambisporaceae was closed correlated with degraded soil, mainly with Al3+, Na+, and bulk soil density properties. On the other hand, Acaulosporaceae and Glomeraceae were positively correlated with native vegetation and restored soil, respectively, thereby improving Shannon index, richness, enzyme activity, and soil respiration. Thus, grazing exclusion, in long term, can be a good strategy to restore AMF-diversity in soils in the Brazilian semiarid.

Soil sodicity affected the arbuscular mycorrhizal community and its interactions with bacteria in the Western Songnen Plain

Soil sodicity affects plant growth and is a crucial factor degrading soil fertility and threatening grain yield worldwide. AM fungi form mutualistic symbiosis with plant roots and alleviate salt stress for the host plant. Therefore, understanding their distribution pattern and interactions with bacteria in natural saline-sodic soils would be essential to improve plant growth. Therefore, we examined AM fungal community and co-occurrence with soil bacteria across a wide sodicity gradient in the Western Songnen Plain. AM fungal traits, including root colonization and ERH (extraradical hyphal) density, showed negative correlations with soil sodicity, while spore density did not show correlation with soil sodicity. In total, 188 AM fungal OTUs were annotated at 97 % identity across 108 soil samples. Soil sodicity decreased AM fungal alpha-diversity and exerted strong influence on their community composition. Rare AM fungi were more sensitive to sodicity than abundant AM fungi, as confirmed by their decrease with the increasing soil sodicity and almost all rare AM fungi belonging to z- OTUs. Abundant rather than rare AM fungi contributed greatly to soil nutrient availability as shown by conducting a random forest analysis. Network analysis revealed a less connected AM fungi-bacteria co-occurrence network in moderately and extremely saline-sodic soils. Further analysis indicated that some bacteria that positively correlated with AM fungi indeed exhibited positive correlations with AM fungal hyphal and spore density. Overall, our results provide evidence that AM fungal community was greatly shaped by soil sodicity in the Songnen Plain, and provides an alternative way to identify positive AM-bacteria interactions in saline-sodic environments.

Drought rearranges preferential carbon allocation to arbuscular mycorrhizal community members co-inhabiting roots of Medicago truncatula

Arbuscular mycorrhizal (AM) fungi establish symbiosis with majority of plant species, supporting their abiotic and biotic stress tolerances, and receiving reduced carbon in return. However, how and why plants control the composition of their associated mycorrhizal communities remains largely unknown. Our aim was to analyze the consequences of abrupt changes in environmental conditions such as light intensity or water supply on carbon allocation from plant (Medicago truncatula) to different AM fungal species coexisting in plant roots, employing 13C labeling and tracing. Significant differences were detected in the composition of synthetic communities of AM fungi just ten days after the environmental change induction. Under simulated drought, plants preferentially allocated their carbon to Funneliformis mosseae to the detriment of Claroideoglomus claroideum. Compared to drought, shading did not lead to a significant rearrangement of carbon fluxes from plants to the different AM fungi. Our observations strongly suggest that plants actively promote, through preferential allocation of their carbon, specific AM fungal symbionts in their roots depending on environmental conditions. Yet, it still needs to be elucidated which fungal traits are playing a role in this process, how are the different symbionts recognized, and which molecular mechanisms are involved in such preferential carbon routing.

Mycorrhization of strawberry plantlets potentiates the synthesis of phytochemicals during ex vitro acclimatization

Ex vitro strawberry plantlets from micropropagation and coinoculated with arbuscular mycorrhizal fungi (AMF) and biochar can provide beneficial health effects. In the present study, we evaluated the effects of different proportions of biochar in the presence and absence of AMF on the production of secondary metabolites in the leaves and roots of strawberry plantlets during ex vitro acclimatization. Additionally, the enzymatic activity of the substrate enriched with AMF and biochar was analyzed. The experiment consisted of the control (absence of the mycorrhizal community) and four biochar proportions (0, 3, 6, and 9% of the volume of the container) coinoculated with AMF. Plantlets produced on substrates enriched with AMF showed higher levels of polyphenols, flavonoids, phenolic acids, and tannins in the tissues analyzed than control plantlets. The combination of AMF and 9% biochar increased the content of total flavonoids in the leaves of strawberry plantlets and increased the activity of phosphatase. The substrate with up to 6% biochar and mycorrhizae showed increased β-glucosidase activity. In conclusion, mycorrhizae are excellent tools to improve the phytochemical quality of strawberry plantlets acclimatized ex vitro. The association between host plants, mycorrhizal symbionts, and bioactivators of these fungi potentiates properties beneficial to health, which can be exploited efficiently in sustainable agriculture.

Microtopographies and soil conditioners on growth and nutrition of </i>Eucalyptus saligna</i> in abandoned agricultural field

Rehabilitation of abandoned agricultural fields is a multidisciplinary task, in pursuit of the development of sustainable productive systems. The objective of this study was to evaluate the effect of microtopography technique and soil conditioners on survival, growth and nutrition of Eucalyptus saligna of an abandoned agriculture field. Plots of microtopography and flat plots were established in an abandoned agriculture field (27º 12.08' S and 49º 07.60' W). Within plots, we stablished subplots with plants, which received the application of soil conditioners, including phonolite (100 g), mycorrhizal inoculant (200 cm3), pulp sludge and carbonized rice husk (200 cm3), phonolite (100 g) and mycorrhizal inoculant (200 cm3) and control. The experiment monitoring occurred between november 2013 to october 2014 and growth parameters were measured after 30, 90, 150, 210, 270 and 330 days of the experiment onset. From each plant, height, stem diameter and canopy area were measured. At the end of the experiment, 50 leaves were collected from each plant to determine potassium and phosphorus concentrations. The native mycorrhizal community was characterized by bioassay and species identification of field-collected spores. Survival rates of Eucalyptus saligna tended to be higher in microtopography plots. The Plant height, stem diameter, canopy area, and shoot P and K concentration were significantly higher in plants at microtopography plots. Soil conditioners influenced significantly the shoot K concentration. The application of microtopography technique improved survival, growth, and nutrition of Eucalyptus saligna, and it represents an important strategy to rehabilitate abandoned agricultural fields.

Regional variation drives differences in microbial communities associated with sugar maple across a latitudinal range.

Climate change is prompting plants to migrate and establish novel interactions in new habitats. Because of the pivotal roles that microbes have on plant health and function, it is important to understand the ecological consequences of these shifts in host-microbe interactions with range expansion. Here we examine how the diversity of plant-associated microbes varies along the host's current range and extended range according with climate change predictions, and assess the relative influence of host genotype (seed provenance) and environment in structuring the host microbiome. We collected sugar maple seeds from across the species current range, then planted them in temperate and mixedwood/transitional forests (current range) and in the boreal region (beyond range but predicted future range in response to climate change). We used amplicon sequencing to quantify bacterial, fungal, and mycorrhizal communities from seedling leaves and roots. Variation among sites and regions were the main drivers of the differences in host microbial communities, whereas seed provenance did not play a large role. No unifying pattern was observed for microbial community richness, diversity, or specialization, demonstrating the complexity of responses of different taxa on above- and belowground plant compartments. Along the latitudinal gradient, we (1) observed reductions in mycorrhizal diversity that can negatively impact maple establishment; (2) and revealed reductions in fungal leaf pathogens that can have opposite effects. Our results highlight the need for an integrated approach including the examination of various microbial taxa on different plant compartments to improve our understanding of plant range shifts and plant-microbe interactions.

Diversity of ectomycorrhizal structures of Larix sukaczewii and Pinus sylvestris

The ecological value of ectomycorrhizal associations is not restricted to the organism level. They play an essential role in plant communities as key to the diversity and sustainability of species. The sustainability of forest stands in urbanised areas depends on preserving mycorrhizal communities’ structural and functional organisation. Reducing species diversity of ectomycorrhizal associations does not lessen the resilience of forest ecosystems in industrial centres but is balanced by morphological diversity.

A Sustainable Intercropping System for Organically Produced Lettuce and Green Onion with the Use of Arbuscular Mycorrhizal Inocula

Arbuscular mycorrhizal fungi (AMF) are efficient for improving crop production and quality in organic farming systems. Our objective was to examine the effects of two AMF inocula, Rhizophagus intraradices and Diversispora spp., against a non-inoculated control on lettuce and green onion grown organically in an intercropping cropping system. At time of harvest, colonization levels were very low, and not different compared to the control that was colonized by the native mycorrhizal community. The yield of inoculated lettuce and green onion was unchanged, as also observed in the root system architecture analysis parameters. In both crops, color was not affected, limiting the possibility for consumers to reject the product. Nitrate accumulation was well below the limits set by European Commission in all treatments. Sugar, chlorophyll, K, Na and P contents were also quantified, showing no particular variations. In AMF-treated lettuce, important phytochemical characteristics, such as phenol content and ascorbic acid, showed a tendency for reduced values, while antioxidant capacity was significantly reduced by both AMF treatments. The study provides a description about the effect of AMF on two important co-cultivated crops. Research should be continued in order to determine best matches between plant material and AMF inocula that could result in enhanced production and nutritional quality.

МИКОРИЗООБРАЗУЮЩИЕ ГРИБЫ В ФОРМИРОВАНИИ БИОГЕОЦЕНОЗОВ: АНАЛИТИЧЕСКИЙ ОБЗОР

This review examines the results of scientific experiments of foreign and domestic researchers in the field of studying mycorrhizal associations, the mechanisms of their symbiosis with plants. The information about the current state of the issue is given: different points of view on the interaction of mycorrhizal plants with mycobionts. A comparative analysis of the development of mycorrhiza in individual plant species was carried out. It was found that the maximum degree of mycorrhiza development corresponds to the beech and linden families. The factors influencing the development of balanced and exploitive mycorrhizal associations are considered. The evolutionary and functional characteristics of the types of mycorrhizae are given. The benefits of mycorrhizal associations are considered, both for tree species and for species of fungi involved in the formation of mycorrhizae. The role of symbionts in mycorrhiza is considered, as well as the form and degree of development of mycorrhiza for mycotrophic plants. An analytical review of the studies of foreign and domestic scientists allowed us to determine the preferred mycorrhizal communities for reforestation. It was noted that unfavorable, extreme environmental conditions in most cases intensified the growth and development of mycorrhizal communities. All these factors should be taken into account when selecting tree species and types of fungi in forestry during reforestation

Contrasting structure of root mycorrhizal communities of black spruce and trembling aspen in different layers of the soil profile in the boreal mixedwoods of eastern Canada

Contrasting structure of root mycorrhizal communities of black spruce and trembling aspen in different layers of the soil profile in the boreal mixedwoods of eastern Canada

Cover crop selection affects maize susceptibility to the fungal pathogen Fusarium verticillioides

In this study, we show the impact of cover crop legacy in soil towards susceptibility of next generation maize to the fungal pathogen Fusarium verticillioides. The use of different plant species as cover crops in organic cropping systems has been shown to provide several ecosystem services. The direct benefits of using leguminous cover crops such as pea or mycorrhizal species such as cereal rye or oats for soil fertility and cash crop yield are well known. However, the impacts of different cover crop species on subsequent cash crop pest suppression is rarely accounted for in agricultural management. Legacy of cover crop species are of importance considering recent findings that plants promoting arbuscular mycorrhizal communities, such as cereal rye and oats as cover crops, can provide increased benefits to successive maize crops against insect pests. In this study, we test whether such benefits might also include resistance against pathogens. We examined progression of rot lesions in ear, stalk and seedling blight by Fusarium verticillioides in maize plants that were grown in soil with a cover crop monoculture history of either winter pea, triticale or radish. This study shows for the first time that soil legacy of mycorrhizal monocot triticale as a cover crop renders maize plants more susceptible to ear rot and seedling blight by Fusarium verticillioides as compared to a soil legacy of radish. This suggests that although soil legacy of radish may be detrimental to management of insects, it is effective in suppressing progression of Fusarium verticillioides in maize. This work demonstrates the significance of cover crop selection to manage fungal pathogens such as Fusarium verticillioides, it further suggests trade-offs in plant resistance to various pests’ taxa at the cover crop species level.