Related Arbuscular Mycorrhizal Fungi Research Articles

Long-Term Manuring Enhanced Compositional Stability of Glomalin-Related Soil Proteins through Arbuscular Mycorrhizal Fungi Regulation

Glomalin-related soil proteins (GRSP) play a crucial role in strengthening soil structure and increasing carbon (C) storage. However, the chemical stability of GRSP and related arbuscular mycorrhizal fungi (AMF) community response to fertilization remains unclear. This study investigated C and nitrogen (N) contents, three-dimensional fluorescence characteristics in GRSP, and AMF properties based on a field experiment that was subjected to 29 years of various fertilizations. The experiment included treatments with no fertilizer (CK), chemical fertilizer (NPK), manure (M), and manure combined with NPK (NPKM) treatments. Results showed that GRSP contained 37–49% C and 6–9% N, respectively. Compared with CK and NPK, the C and N proportions in GRSP significantly increased under M and NPKM. Using the parallel factor model, four fluorescent components of GRSP were identified: one fulvic acid-like component (C2), one tyrosine-like component (C4), and two humic acid-like components (C1, C3). Under M and NPKM, the fluorescent intensity of C2 and C4 decreased, while the humification index (HIX) increased relative to CK and NPK, indicating that organic fertilization could enhance the stability of GRSP. The C and N proportion in GRSP positively associated with soil organic C (SOC), total N (TN), available phosphorus (AP), AMF biomass, and diversity, while C2 and C4 showed negative associations. Structural equation modeling further revealed that manure-induced changes in pH, SOC, TN, and AP increased AMF biomass and diversity, thereby altering GRSP composition and stability. This study provides valuable insights into the compositional traits of GRSP, contributing to sustainable soil management and C sequestration in agroecosystems.

Soil Traits and Grapevine Rootstock Genotypes Modulate Arbuscular Mycorrhizal Rate and Species in a Mediterranean Environment

The soil microbiota is a key component of agroecosystems, and understanding its traits is crucial for effective agronomic management. Among beneficial microorganisms, arbuscular mycorrhizal fungi (AMFs) are mutually associated with grapevine (Vitis vinifera L.), enhancing the ability of this cropping system to adapt to soil conditions and bolstering its resistance and resilience against abiotic stresses, particularly drought, by promoting root growth and enhancing the roots’ absorption surface. The objective of this on-field study was to determine AMF species richness and diversity along with their relation to soil chemical, physical, and biological characteristics in two adjacent organic vineyards in Central Italy. The two tested vineyards of the autochthonous cv. Aleatico differed by the presence of grafted (Vitis berlandieri × V. riparia rootstock; AL-420) or own-rooted (ungrafted V. vinifera L.; AL-ORV) vines. To this aim, soil and root samples were collected and geo-referenced. Analysis of the AMF species colonizing roots of both AL-ORV and AL-420 revealed the presence of four species: Scutellospora alterata, Paraglomus laccatum, Acaulospora laevis, and A. baetica, with S. alterata being the most frequent. Mycorrhization parameters were higher in the roots of grafted plants compared to ungrafted ones. A high beta-glucosidase (BG):N-acetylglusosaminidase (NAG) ratio in two tested vineyards indicated that microbes utilized more cellulose than chitin and peptidoglycan as dominant C resources. A negative correlation between mycorrhization rate (MyCP) and BG was observed, likely because AMFs form mutualistic relationships with plants, depending on the host plant for carbon. Results revealed a positive correlation between the degree of mycorrhizal association and the species involved, with the presence of copper and nickel among metals. Negative correlations were found concerning soil clay content along with beta-glucosidase. In conclusion, the grapevine root system was characterized by a differential symbiotic relationship with AMF species, whose development is influenced by the root genotype, soil texture, and biochemistry. Specifically, the increased frequency of AMFs in relation to copper content strengthens the evidence of their role in maintaining a vine’s production capacity in the event of soil contamination by this element.

Hierarchical phylogenetic community assembly of soil protists in a temperate agricultural field.

Protists are abundant, diverse and perform essential functions in soils. Protistan community structure and its change across time or space are traditionally studied at the species level but the relative importance of the processes shaping these patterns depends on the taxon phylogenetic resolution. Using 18S rDNA amplicon data of the Cercozoa, a group of dominant soil protists, from an agricultural field in western Germany, we observed a turnover of relatively closely related taxa (from sequence variants to genus-level clades) across soil depth; while across soil habitats (rhizosphere, bulk soil, drilosphere), we observed turnover of relatively distantly related taxa, confirming Paracercomonadidae as a rhizosphere-associated clade. We extended our approach to show that closely related Cercozoa encounter divergent arbuscular mycorrhizal (AM) fungi across soil depth and that distantly related Cercozoa encounter closely related AM fungi across soil compartments. This study suggests that soil Cercozoa community assembly at the field scale is driven by niche-based processes shaped by evolutionary legacy of adaptation to conditions primarily related to the soil compartment, followed by the soil layer, giving a deeper understanding on the selection pressures that shaped their evolution.

Precipitation and temperature shape the biogeography of arbuscular mycorrhizal fungi across the Brazilian Caatinga

AbstractAimDeterministic and neutral processes shape the biogeography of fungi. Arbuscular mycorrhizal fungi (AMF), an important group of plant root symbionts, remains poorly studied in the Neotropics. Here, we provided the first molecular survey of AMF diversity and tested whether the environment or space shapes AMF biogeography along a 12° latitudinal transect in the Brazilian Caatinga, a unique tropical dry forest ecoregion.LocationCaatinga, Brazil.TaxonArbuscular mycorrhizal fungi (Glomeromycotina).MethodsSoil and root samples were collected across a latitudinal transect of 1500 km within the Brazilian Caatinga. AMF communities were characterized using Illumina LSU amplicon sequencing. Operational taxonomic unit (OTU) richness, composition and phylogenetic niche conservatism were assessed using univariate and multivariate analyses, and the potential for new taxa discovery was assessed with BLAST analysis against reference and environmental sequences sets.ResultGlomeraceae was the most abundant and diverse family, resembling more dry Saharo‐Arabian and Australian realms or European croplands than other tropical forests from South America, but 10% of the OTUs could be taxa new to science, especially within Archaeospora, Claroideoglomus, Acaulospora, Gigaspora, Dentiscutata and Redeckera. AMF communities showed strong biogeographical structure inconsistent with a classical latitudinal diversity gradient, which further differed between soil and roots. Soil AMF biogeography best correlated with precipitation; community composition converged and richness increased towards both ends of the latitudinal transect where precipitation increased. Root AMF biogeography correlated to temperature, with decreasing diversity at higher temperatures. We found no evidence of phylogenetic niche conservatism.Main conclusionsNiche‐based processes driven by regional climate, most importantly precipitation and temperature, shape AMF biogeography across the Caatinga, with niche divergence among closely related AMF taxa. Given the expected future decrease in precipitation and increase in temperature, climate change may strongly affect the unique and yet unknown AMF biodiversity in neotropical dry forests.

Unraveling the AM fungal community for understanding its ecosystem resilience to changed climate in agroecosystems

The changing global climate affects the agroecosystem making it challenging to achieve the world’s sustainable development goals. Among the facets of belowground microbial communities, the arbuscular mycorrhizal fungi (AMF) hold an important place. They represent the most common symbiont phylum colonizing more than 80% of the plant families and are likely to be affected by global climate change. These fungi facilitate plant’s mineral acquisition, improving growth and protecting them from biotic and abiotic stresses. The elevated carbon dioxide (eCO2) level, temperature, increased nitrogen and phosphorus deposition influences the plant phenology and AMF functioning through changes in diversity and community composition of AMF. The interaction effects of soil management practices due to climate change affect the system productivity and perturb mineral cycling. Understanding the carbon and nitrogen cycling of an agro-ecosystem and its associated AMF communities concerning ecosystem productivity is the need of the hour. Plant-fungal associations require a more environment resilient approach to ameliorate the effect of anthropogenic changes in carbon and nitrogen cycles. Since AMF communities alter due to local environmental conditions and land-use changes, the most adapted community may help in predicting the mycorrhizal responses to chemical fertilizers, eCO2, temperature and drought. In this review, we aimed at investigating (i) the diversity and community composition of AMF in relation to the change in crop and soil management practices, and (ii) how the adapted AMF communities may perform in maintaining the ecosystem resilience of these agroecosystems under climate change conditions. Hence, AMF-plant symbiosis can be effectively integrated into global climate change models. Eventually, the ecosystem resilience will be better understood to exploit the resident AMF communities to offset some of the detrimental effects of anthropogenic environmental change.

Dynamics of arbuscular mycorrhizal fungi in relation to root colonization, spore density, and soil properties among different spreading stages of the exotic plant threeflower beggarweed (Desmodium triflorum) in aZoysia tenuifolialawn

AbstractWeed invasion is a prevailing problem in modestly managed lawns. Less attention has been given to the exploration of the role of arbuscular mycorrhizal fungi (AMF) under different invasion pressures from lawn weeds. We conducted a four-season investigation into aZoysia tenuifoliaWilld. ex Thiele (native turfgrass)–threeflower beggarweed [Desmodium triflorum(L.) DC.] (invasive weed) co-occurring lawn. The root mycorrhizal colonizations of the two plants, the soil AM fungal communities and the spore densities under five different coverage levels ofD. triflorumwere investigated.Desmodium triflorumshowed significantly higher root hyphal and vesicular colonizations than those ofZ. tenuifolia, while the root colonizations of both species varied significantly among seasons. The increased coverage ofD. triflorumresulted in the following effects: (1) the spore density initially correlated with mycorrhizal colonizations ofZ. tenuifoliabut gradually correlated with those ofD. triflorum. (2) Correlations among soil properties, spore densities, and mycorrhizal colonizations were more pronounced in the higher coverage levels. (3) Soil AMF community compositions and relative abundances of AMF operational taxonomic units changed markedly in response to the increased invasion pressure. The results provide strong evidence thatD. triflorumpossessed a more intense AMF infection thanZ. tenuifolia, thus giving rise to the altered host contributions to sporulation, soil AMF communities, relations of soil properties, spore densities, and root colonizations of the two plants, all of which are pivotal for the successful invasion ofD. triflorumin lawns.

Arbuscular Mycorrhizal Fungi – Their Life and Function in Ecosystem

Abstract Arbuscular mycorrhizal fungi living in the soil closely collaborate with plants in their root zone and play very important role in their evolution. Their symbiosis stimulates plant growth and resistance to different environmental stresses. Plant root system, extended by mycelium of arbuscular mycorrhizal fungi, has better capability to reach the water and dissolved nutrients from a much larger volume of soil. This could solve the problem of imminent depletion of phosphate stock, affect plant fertilisation, and contribute to sustainable production of foods, feeds, biofuel, and raw materials. Expanded plant root systems reduce erosion of soil, improve soil quality, and extend the diversity of soil microflora. On the other hand, symbiosis with plants affects species diversity of arbuscular mycorrhizal fungi and increased plant diversity supports diversity of fungi. This review summarizes the importance of arbuscular mycorrhizal fungi in relation to beneficial potential of their symbiosis with plants, and their function in the ecosystem.

Growth benefits provided by different arbuscular mycorrhizal fungi to Plantago lanceolata depend on the form of available phosphorus

Strains of arbuscular mycorrhizal fungi (AMF) differ markedly in the growth benefits they provide to plants. We investigated whether these differences depend on the chemical form of inorganic phosphorus. The closely related AMF Glomus custos and Rhizophagus irregularis were compared using Plantago lanceolata as the host plant, grown in quartz sand with either soluble orthophosphate or sparingly soluble hydroxyapatite as a sole source of phosphorus. In a growth experiment with AMF-inoculated plants in a climate chamber, sampling at 3-wk intervals enabled a detailed time-resolved analysis of shoot and root phosphorus concentrations and growth performance of P. lanceolata. The ability of AMF to enhance plant growth and deliver phosphate depended strongly on the identity of the available phosphorus source. In orthophosphate-amended substrate only modest differences in plant growth performance (dry matter accumulation and allocation, phosphorus acquisition) were observed between the two AMFs, despite evident AMF root colonization as shown by strain-specific mtLSU qPCR analysis. The treatment with hydroxyapatite however, created stringent growth-limiting conditions and significantly increased the growth benefit provided by R. irregularis over G. custos and the non-mycorrhizal treatment. Plants with R. irregularis could acquire much more phosphorus from apatite compared to G. custos. There were also differences in shoot-to-root dry matter allocation and plant tissue phosphorus concentrations between the R. irregularis and G. custos treatments. Our observations suggest that in experiments on the symbiosis between plants and mycorrhizal fungi more attention should be paid to the chemical form of phosphorus in soil.

High intraspecific genome diversity in the model arbuscular mycorrhizal symbiont Rhizophagus irregularis.

Arbuscular mycorrhizal fungi (AMF) are known to improve plant fitness through the establishment of mycorrhizal symbioses. Genetic and phenotypic variations among closely related AMF isolates can significantly affect plant growth, but the genomic changes underlying this variability are unclear. To address this issue, we improved the genome assembly and gene annotation of the model strain Rhizophagus irregularis DAOM197198, and compared its gene content with five isolates of R.irregularis sampled in the same field. All isolates harbor striking genome variations, with large numbers of isolate-specific genes, gene family expansions, and evidence of interisolate genetic exchange. The observed variability affects all gene ontology terms and PFAM protein domains, as well as putative mycorrhiza-induced small secreted effector-like proteins and other symbiosis differentially expressed genes. High variability is also found in active transposable elements. Overall, these findings indicate a substantial divergence in the functioning capacity of isolates harvested from the same field, and thus their genetic potential for adaptation to biotic and abiotic changes. Our data also provide a first glimpse into the genome diversity that resides within natural populations of these symbionts, and open avenues for future analyses of plant-AMF interactions that link AMF genome variation with plant phenotype and fitness.

High-resolution community profiling of arbuscular mycorrhizal fungi.

Community analyses of arbuscular mycorrhizal fungi (AMF) using ribosomal small subunit (SSU) or internal transcribed spacer (ITS) DNA sequences often suffer from low resolution or coverage. We developed a novel sequencing based approach for a highly resolving and specific profiling of AMF communities. We took advantage of previously established AMF-specific PCR primers that amplify a c. 1.5-kb long fragment covering parts of SSU, ITS and parts of the large ribosomal subunit (LSU), and we sequenced the resulting amplicons with single molecule real-time (SMRT) sequencing. The method was applicable to soil and root samples, detected all major AMF families and successfully discriminated closely related AMF species, which would not be discernible using SSU sequences. In inoculation tests we could trace the introduced AMF inoculum at the molecular level. One of the introduced strains almost replaced the local strain(s), revealing that AMF inoculation can have a profound impact on the native community. The methodology presented offers researchers a powerful new tool for AMF community analysis because it unifies improved specificity and enhanced resolution, whereas the drawback of medium sequencing throughput appears of lesser importance for low-diversity groups such as AMF.

Integrated multi‐omics analysis supports role of lysophosphatidylcholine and related glycerophospholipids in theLotus japonicus–Glomus intraradicesmycorrhizal symbiosis

Interaction of plant roots with arbuscular mycorrhizal fungi (AMF) is a complex trait resulting in cooperative interactions among the two symbionts including bidirectional exchange of resources. To study arbuscular mycorrhizal symbiosis (AMS) trait variation in the model plant Lotus japonicus, we performed an integrated multi-omics analysis with a focus on plant and fungal phospholipid (PL) metabolism and biological significance of lysophosphatidylcholine (LPC). Our results support the role of LPC as a bioactive compound eliciting cellular and molecular response mechanisms in Lotus. Evidence is provided for large interspecific chemical diversity of LPC species among mycorrhizae with related AMF species. Lipid, gene expression and elemental profiling emphasize the Lotus-Glomus intraradices interaction as distinct from other arbuscular mycorrhizal (AM) interactions. In G. intraradices, genes involved in fatty acid (FA) elongation and biosynthesis of unsaturated FAs were enhanced, while in Lotus, FA synthesis genes were up-regulated during AMS. Furthermore, FAS protein localization to mitochondria suggests FA biosynthesis and elongation may also occur in AMF. Our results suggest the existence of interspecific partitioning of PL resources for generation of LPC and novel candidate bioactive PLs in the Lotus-G. intraradices symbiosis. Moreover, the data advocate research with phylogenetically diverse Glomeromycota species for a broader understanding of the molecular underpinnings of AMS.

Diversidad de géneros de hongos formadores de micorrizas arbusculares asociados a pasto colosuana (Bothriochloa pertusa (L) A. Camus) en suelos compactados y no compactados del municipio de San Marcos, Sucre-Colombia

El objetivo del presente trabajo consistió en identificar la diversidad de hongos formadores de micorrizas arbusculares (HMA) asociadas a pasto colosoana presentes en suelos compactados y no compactados del municipio de San Marcos departamento de Sucre, Colombia. De cada sitio seleccionado se tomó muestra de suelo y raíces, de las cuales se aislaron esporas de HMA, se determinó el porcentaje de colonización de estos hongos en raíces, se realizó identificación de géneros y/o especies de HMA, se correlaciono la densidad de HMA y % de colonización con parámetros físicos, químicos y biológicos del suelo objeto de estudio. La densidad de esporas de HMA esta correlacionada directa y significativamente con los parámetros fisicoquímicos: materia orgánica, fosforo, densidad aparente, y correlacionado negativamente con la porosidad total y porcentaje de humedad. Fueron aislados e identificados 31 morfotipos de hongos formadores de micorrizas arbusculares en suelos de zonas compactadas y no compactadas, distribuidos taxonómicamente en once géneros predominando el género Glomus con un 48 %, determinándose de esta manera una gran diversidad de géneros de HMA en la relación al estado, uso y manejo del suelo en el área de estudio.

The co-existence between DSE and AMF symbionts affects plant P pools through P mineralization and solubilization processes

Abstract The capacity of dark septate endophytes (DSE; Phialocephala turiciensis, Acephala applanata, P. glacialis and Phaeomollisia piceae) to solubilize inorganic phosphate (P) and to mineralize the organic form was studied. We analysed the effect of DSE strains on P uptake by Trifolium repens in the presence or absence of arbuscular mycorrhizal fungi (AMF). Phosphatases were observed both in the absence of the host plant and the organic resource, showing that the P mineralization process is not induced by the enzyme substrate or the host. DSE were more efficient at mineralizing organic P. Independently of the presence of AMF, DSE increased the pool of P in the soil, with significant differences being found in P levels among the different DSE. In contrast, plant P uptake was increased by AMF. The P content of plants increased with the co-inoculation of AMF and P. turiciensis or P. piceae. We hypothesize a close relationship between DSE and AMF in relation to P availability and uptake in plants. Whereas DSE increase the pool of P in the rhizosphere, AMF are responsible for P transfer to the host, with co-colonization of plants by DSE and AMF showing a synergistic outcome.

Plant-driven genome selection of arbuscular mycorrhizal fungi.

Plant-driven genome selection of arbuscular mycorrhizal fungi.

Arbuscular mycorrhizal fungal communities are phylogenetically clustered at small scales.

Next-generation sequencing technologies with markers covering the full Glomeromycota phylum were used to uncover phylogenetic community structure of arbuscular mycorrhizal fungi (AMF) associated with Festuca brevipila. The study system was a semi-arid grassland with high plant diversity and a steep environmental gradient in pH, C, N, P and soil water content. The AMF community in roots and rhizosphere soil were analyzed separately and consisted of 74 distinct operational taxonomic units (OTUs) in total. Community-level variance partitioning showed that the role of environmental factors in determining AM species composition was marginal when controlling for spatial autocorrelation at multiple scales. Instead, phylogenetic distance and spatial distance were major correlates of AMF communities: OTUs that were more closely related (and which therefore may have similar traits) were more likely to co-occur. This pattern was insensitive to phylogenetic sampling breadth. Given the minor effects of the environment, we propose that at small scales closely related AMF positively associate through biotic factors such as plant-AMF filtering and interactions within the soil biota.

Intense competition between arbuscular mycorrhizal mutualists in an in vitro root microbiome negatively affects total fungal abundance

The root microbiome is composed of an incredibly diverse microbial community that provides services to the plant. A major question in rhizosphere research is how species in root microbiome communities interact with each other and their host. In the nutrient mutualism between host plants and arbuscular mycorrhizal fungi (AMF), competition often leads to certain species dominating host colonization, with the outcome being dependent on environmental conditions. In the past, it has been difficult to quantify the abundance of closely related species and track competitive interactions in different regions of the rhizosphere, specifically within and outside the host. Here, we used an artificial root system (in vitro root organ cultures) to investigate intraradical (within the root) and extraradical (outside the root) competitive interactions between two closely related AMF species, Rhizophagus irregularis and Glomus aggregatum, under different phosphorus availabilities. We found that competitive interactions between AMF species reduced overall fungal abundance. R.irregularis was consistently the most abundant symbiont for both intraradical and extraradical colonization. Competition was the most intense for resources within the host, where both species negatively affected each other's abundance. We found the investment ratio (i.e. extraradical abundance/intraradical abundance) shifted for both species depending on whether competitors were present or not. Phosphorus availability did not change the outcome of these interactions. Our results suggest that studies on competitive interactions should focus on intraradical colonization dynamics and consider how changes in investment ratio are mediated by fungal species interactions.

Relatedness among arbuscular mycorrhizal fungi drives plant growth and intraspecific fungal coexistence.

Arbuscular mycorrhizal fungi (AMF) form symbioses with most plant species. They are ecologically important determinants of plant growth and diversity. Considerable genetic variation occurs in AMF populations. Thus, plants are exposed to AMF of varying relatedness to each other. Very little is known about either the effects of coexisting AMF on plant growth or which factors influence intraspecific AMF coexistence within roots. No studies have addressed whether the genetics of coexisting AMF, and more specifically their relatedness, influences plant growth and AMF coexistence. Relatedness is expected to influence coexistence between individuals, and it has been suggested that decreasing ability of symbionts to coexist can have negative effects on the growth of the host. We tested the effect of a gradient of AMF genetic relatedness on the growth of two plant species. Increasing relatedness between AMFs lead to markedly greater plant growth (27% biomass increase with closely related compared to distantly related AMF). In one plant species, closely related AMF coexisted in fairly equal proportions but decreasing relatedness lead to a very strong disequilibrium between AMF in roots, indicating much stronger competition. Given the strength of the effects with such a shallow relatedness gradient and the fact that in the field plants are exposed to a steeper gradient, we consider that AMF relatedness can have a strong role in plant growth and the ability of AMF to coexist. We conclude that AMF relatedness is a driver of plant growth and that relatedness is also a strong driver of intraspecific coexistence of these ecologically important symbionts.

Abundance of arbuscular mycorrhizal fungi in relation to soil salinity around Lake Urmia in northern Iran analyzed by use of lipid biomarkers and microscopy

Saline soils around Lake Urmia in northern Iran constitute a stressed environment for plants and microbial communities, including arbuscular mycorrhizal (AM) fungi. Soil and root samples were collected from fields cultivated with the glycophytes Allium cepa L. and Medicago sativa L., and sites dominated by the halophyte Salicornia europaea L. Soil and root samples were analyzed for the AM fungal signature neutral lipid fatty acid (NLFA) 16:1ω5. The roots were also examined microscopically for mycorrhizal colonization. Each plant species was sampled across a salt gradient. Microscopic examination showed no AM fungal structures in the roots of S. europaea. The highest root colonization was recorded for M. sativa. The highest NLFA 16:1ω5 values were found in soil around M. sativa roots and the lowest in soil around S. europaea roots. We found evidence for stimulation of vesicle formation at moderate salinity levels in M. sativa, which is an indication of increased carbon allocation to mycorrhiza. On the other hand, we found a negative correlation between salinity and arbuscule formation in A. cepa, which may indicate a less functional symbiosis in saline soils.

Plant facilitation occurs between species differing in their associated arbuscular mycorrhizal fungi

Complementary beneficial effects of different arbuscular mycorrhizal fungi (AMF) can result in a more efficient exploitation of the soil nutrients available, thus influencing plant communities. Here, we hypothesize that plant-AMF specificity is mediated by phylogenetic constraints defining possible interactions, and that plant-AMF interaction patterns can influence plant-plant facilitation specificity. We reanalyzed previous data describing plant-plant and plant-AMF interaction at the community level to specifically test for a phylogenetic signal on plant and AMF interactions and for a relationship between plant-plant facilitation specificity and plant species differences in their AMF associates. Closely related AMF operational taxonomical units (OTUs) tend to interact with the same plant species, but there is not a significant signal in the interaction through the plant phylogeny. This indicates that the similarity in the AMF associates of two plant species is independent of their phylogenetic relatedness. Interestingly, plant-AMF interactions match plant facilitation specificity, with pairs of plant species recruiting more frequently under each other tending to have different AMF associates. An increment of AMF diversity in the rhizosphere, as a result of plant-AMF and plant-plant selectivity, is suggested as a potential driver of plant-plant facilitation. This study highlights the role of plant-AMF interactions in shaping plant community assemblages.

Molecular diversity of arbuscular mycorrhizal fungi in relation to soil chemical properties and heavy metal contamination

Abundance and diversity of arbuscular mycorrhizal fungi (AMF) associated with dominant plant species were studied along a transect from highly lead (Pb) and zinc (Zn) polluted to non-polluted soil at the Anguran open pit mine in Iran. Using an established primer set for AMF in the internal transcribed spacer (ITS) region of rDNA, nine different AMF sequence types were distinguished after phylogenetic analyses, showing remarkable differences in their distribution patterns along the transect. With decreasing Pb and Zn concentration, the number of AMF sequence types increased, however one sequence type was only found in the highly contaminated area. Multivariate statistical analysis revealed that further factors than HM soil concentration affect the AMF community at contaminated sites. Specifically, the soils’ calcium carbonate equivalent and available P proved to be of importance, which illustrates that field studies on AMF distribution should also consider important environmental factors and their possible interactions.