Distribution Of Arbuscular Mycorrhizal Fungi Research Articles

Evaluation of arbuscular mycorrhizal fungi in cultivated crops

Arbuscular mycorrhizal fungi are ubiquitous and form a symbiotic association with many higher plants. They improve mineral nutrient uptake and enhance abiotic stress tolerance. Common cultivated crops (green pea, chick pea, red lentil, green gram, tomato, black gram and pigeon pea) at Aligarh District were evaluated to ascertain the presence and dominance of AM fungi. Glomus was the predominant genus and showed high frequency of occurrence at all the sites investigated. Five species belongs to genera Glomus (G. fasciculatum, G. mosseae, G. etunicatum, G. macrocarpum and G. constrictum) were found to be associated with these crops. Distribution of AM fungi on studied crops was tomato > green pea > chickpeas > black gram > red lentil > pigeon pea. G. fasciculatum register the dominancy in terms of spore count in this study whereas G. constrictum trail the spore count.

Diversity and Distribution of Arbuscular Mycorrhizal Fungi in Selected Medicinal Plants

Background: Tha Arbuscular Mycorrhizal Fungi (AMF) association previously known as VAM belongs to an ancient fungal group known as Glomeromycota. In this study five commonly used medicinal plants viz., Eclipta prostrata, Mentha arvensis, Elettaria cardamomum, Bacopa monneri and Mimosa pudica were investigated for AMF colonization in the form of arbuscules, vesicles and hyphae from their roots and their rhizospheric soil was isolated for AMF spores. Majorly two genera of AMF dominated the rhizospheric soil of the plants investigated which were Acaulospora and Glomus. Altogether 12 AMF spores were isolated from the rhizospheric environment of the plants and they belonged to six different genera of AMF. Methods: In this field-laboratory investigation during 2022-23, different localities of Banaras Hindu University was surveyed. 5 different plants were selected for investigation on the diversity and distribution of AMF colonisation found in their rhizospheric soil. Result: Our investigation on the diversity and distribution of AMF of few selected plants from BHU have allowed us to isolate and morphologically identify 12 different species of AMF from 6 different genera. The geographical distribution of the collected species was discussed. The present work will be a complementary contribution to the comprehensive study of the identification and utility of AMF in plant growth and sust.

Australia offers unique insight into the ecology of arbuscular mycorrhizal fungi: An opportunity not to be lost

AbstractTypified by ancient soils and unique assemblages of flora, Australia provides opportunities to expand our understanding of arbuscular mycorrhizal (AM) fungi. Despite their ubiquity, key aspects of Australian AM fungal ecology remain buried due to our limited knowledge of their biogeography and their potential adaptation to Australia's environmental conditions. This knowledge gap is particularly extraordinary given that the characteristics of the Australian environment are likely to provide unique insights into AM fungal ecology and evolution. Extensive exploration of the diversity and distribution of AM fungi across the continent is overdue. In pursuit of this goal, ecologists should employ the most effective and pragmatic molecular approaches, while making use of well‐curated databases. We urge researchers to examine the biogeography of Australian AM fungi meaningfully, leveraging the distinctive attributes of Australian landscapes, such as the demographics of plant mycorrhizal types and the characteristic interplay with fire. Documenting AM fungal communities across Australia will not only provide unique insights into their ecology but is also pivotal to being able to incorporate these organisms into land management for conservation, restoration and sustainable agriculture.

Abundance and distribution of arbuscular mycorrhizal fungi associated with oil-yielding plants.

Due to their role in nutrient transmission, arbuscular mycorrhizal fungi (AMF) are widespread plant root symbionts. They may improve plant production by altering plant community structure and function. Therefore, a study was conducted in the state of Haryana to analyze the distribution pattern, diversity, and association of different AMF species with oil-yielding plants. The results of the study revealed the percentage of root colonization, sporulation, and diversity of fungal species associated with the selected 30 oil-yielding plants. The percentage root colonization ranged from 0% to 100%, the highest in Helianthus annuus (100.00 ± 0.00) and Zea mays (100.00 ± 0.00) and the least in Citrus aurantium (11.87 ± 1.43). At the same time, there was no root colonization in the Brassicaceae family. The number of AMF spores present in 50 g of soil samples varied from 17.41 ± 5.28 to 497.2 ± 8.38, with maximum spore population in Glycine max (497.2 ± 8.38) and minimum in Brassica napus (17.41 ± 5.28). Besides, the presence of several species of different genera of AMF was reported in all the studied oil-yielding plants, that is, 60 AMF belonging to six genera viz. Acaulospora, Entrophospora, Glomus, Gigaspora, Sclerocystis, and Scutellospora were observed. Overall, this study will promote AMF usage in oil-yielding plants.

Changes of root AMF community structure and colonization levels under distribution pattern of geographical substitute for four Stipa species in arid steppe

The establishment of symbiotic relationship between arbuscular mycorrhizal fungi (AMF) and roots is a mutually beneficial process and plays an important role in plant succession in ecosystems. However, there is less understanding of information about the AMF community in roots under vegetation succession on a large regional scale, especially the spatial variation in the AMF community and its potential ecological functions. Here, we elucidated the spatial variations in root AMF community structure and root colonization along a distribution pattern of four zonal Stipa species in arid and semiarid grassland systems and explored key factors regulating AMF structure and mycorrhizal symbiotic interactions. Four Stipa species established a symbiosis with AMF, and annual mean temperature (MAT) and soil fertility were the main positive and negative driving factors of AM colonization, respectively. The Chao richness and Shannon diversity of AMF community in the root system of Stipa species tended to increase firstly from S. baicalensis to S. grandis and then decreased from S. grandis to S. breviflora. While evenness of root AMF and root colonization showed a trend of increasing from S. baicalensis to S. breviflora, and biodiversity was principally affected by soil total phosphorus (TP), organic phosphorus (Po) and MAT. It is emphasized that Stipa species have certain dependence on AMF, especially in a warming environment, and the root AMF community structure among the four Stipa taxa was different. Additionally, the composition and spatial distribution of root AMF in host plants varied with MAT, annual mean precipitation (MAP), TP and host plant species. These results will broaden our understanding of the relationship between plant and AMF communities and their ecological role, and provide basic information for the application of AMF in the conservation and rehabilitation of forage plants in degraded semiarid grasslands.

Ecological drivers of fine-scale distribution of arbuscular mycorrhizal fungi in a semiarid Mediterranean scrubland.

Arbuscular mycorrhizal (AM) fungi enhance the uptake of water and minerals by the plant hosts, alleviating plant stress. Therefore, AM fungal-plant interactions are particularly important in drylands and other stressful ecosystems. We aimed to determine the combined and independent effects of above- and below-ground plant community attributes (i.e. diversity and composition), soil heterogeneity and spatial covariates on the spatial structure of the AM fungal communities in a semiarid Mediterranean scrubland. Furthermore, we evaluated how the phylogenetic relatedness of both plants and AM fungi shapes these symbiotic relationships. We characterized the composition and diversity of AM fungal and plant communities in a dry Mediterranean scrubland taxonomically and phylogenetically, using DNA metabarcoding and a spatially explicit sampling design at the plant neighbourhood scale. The above- and below-ground plant community attributes, soil physicochemical properties and spatial variables explained unique fractions of AM fungal diversity and composition. Mainly, variations in plant composition affected the AM fungal composition and diversity. Our results also showed that particular AM fungal taxa tended to be associated with closely related plant species, suggesting the existence of a phylogenetic signal. Although soil texture, fertility and pH affected AM fungal community assembly, spatial factors had a greater influence on AM fungal community composition and diversity than soil physicochemical properties. Our results highlight that the more easily accessible above-ground vegetation is a reliable indicator of the linkages between plant roots and AM fungi. We also emphasize the importance of soil physicochemical properties in addition to below-ground plant information, while accounting for the phylogenetic relationships of both plants and fungi, because these factors improve our ability to predict the relationships between AM fungal and plant communities.

Modeling geographic distribution of arbuscular mycorrhizal fungi from molecular evidence in soils of Argentinean Puna using a maximum entropy approach.

The biogeographic region of Argentinean Puna mainly extends at elevations higher than 3,000 m within the Andean Plateau and hosts diverse ecological communities highly adapted to extreme aridity and low temperatures. Soils of Puna are typically poorly evolved and geomorphology is shaped by drainage networks, resulting in highly vegetated endorheic basins and hypersaline basins known as salar or salt flats. Local communities rely on soil fertility for agricultural practices and on pastures for livestock rearing. From this perspective, investigating the scarcely explored microbiological diversity of these soils as indicators of ecosystems functioning might help to predict the fragility of these harsh environments. In this study we collected soil samples from 28 points, following a nested design within three different macro-habitats, i.e., Puna grassland, hypersaline salar and family-run crop fields. Total fungi and arbuscular mycorrhizal fungi (AMF) occurrence were analyzed using eDNA sequencing. In addition, the significance of soil salinity and organic matter content as significant predictors of AMF occurrence, was assessed through Generalized Linear Mixed Modeling. We also investigated whether intensive grazing by cattle and lama in Puna grasslands may reduce the presence of AMF in these highly disturbed soils, driving or not major ecological changes, but no consistent results were found, suggesting that more specific experiments and further investigations may address the question more specifically. Finally, to predict the suitability for AMF in the different macro-habitats, Species Distribution Modeling (SDM) was performed within an environmental coherent area comprising both the phytogeographic regions of Puna and Altoandino. We modeled AMF distribution with a maximum entropy approach, including bioclimatic and edaphic predictors and obtaining maps of environmental suitability for AMF within the predicted areas. To assess the impact of farming on AMF occurrence, we set a new series of models excluding the cultivated Chaupi Rodeo samples. Overall, SDM predicted a lower suitability for AMF in hypersaline salar areas, while grassland habitats and a wider temperature seasonality range appear to be factors significantly related to AMF enrichment, suggesting a main role of seasonal dynamics in shaping AMF communities. The highest abundance of AMF was observed in Vicia faba crop fields, while potato fields yielded a very low AMF occurrence. The models excluding the cultivated Chaupi Rodeo samples highlighted that if these cultivated areas had theoretically remained unmanaged habitats of Puna and Altoandino, then large-scale soil features and local bioclimatic constraints would likely support a lower suitability for AMF. Using SDM we evidenced the influence of bioclimatic, edaphic and anthropic predictors in shaping AMF occurrence and highlighted the relevance of considering human activities to accurately predict AMF distribution.

Biodiversity and Variations of Arbuscular Mycorrhizal Fungi Associated with Roots along Elevations in Mt. Taibai of China

(1) Background: environmental gradient strongly affects microbial biodiversity, but which factors drive the diversity of arbuscular mycorrhizal fungi (AMF) associated with roots at relatively large spatial scales requires further research; (2) Methods: an experiment on large spatial scales of Mt. Taibai was conducted to explore the biodiversity and drivers of AMF-associated with roots using high-throughput sequencing; (3) Results: a total of 287 operational taxonomic units (OTUs) belong to 62 species representing 4 identified and 1 unclassified order were identified along different altitudinal gradients. With increasing altitude, AMF colonization could be simulated by a quadratic function trend, and altitude has a significant impact on colonization. AMF alpha diversity, including the Sobs and Shannon indexes, tended to be quadratic function trends with increasing altitude. The highest diversity indices occurred at mid-altitudes, and altitude had a significant effect on them. AMF communities have different affinities with soil and root nutrient, and Glomus is most affected by soil and root nutrient factors through the analysis of the heatmap. Glomus are the most dominant, with an occurrence frequency of 91.67% and a relative abundance of 61.29% and 53.58% at the level of species and OTU, respectively. Furthermore, AMF diversity were mostly associated with soil and root nutrients; (4) Conclusions: in general, AMF molecular diversity is abundant in Mt. Taibai, and altitude and nutrient properties of soil and root are the main influencing factors on AMF diversity and distribution.

Arbuscular Mycorrhizal Fungi Associated with Roots Reveal High Diversity Levels at Different Elevations in Tropical Montane Rainforests

(1) Background: Understanding the diversity of communities of arbuscular mycorrhizal fungi (AMF) is the basis for understanding the ecological functions of AMF. (2) Methods: The community diversity and distribution of AMF at different elevations in tropical montane rainforests of Mt. Jianfenfling and Mt. Diaoluo were explored using high-throughput sequencing technology. (3) Results: A total of 283 AMF operational taxonomic units (OTUs) were identified from roots and the number of unique OTUs was 173, accounting for 61.13% of the total number discovered in these tropical montane rainforests. At different altitudes, high turnovers of AMF were observed, with the maximum proportion of unique OTUs between two altitudes being 45.16%, recorded between a.s.l. 250 m and 900 m on Mt. Diaoluo. The highest Sobs, Shannon and Pielou diversity indices appeared at 650 m on Mt. Diaoluo. For the two mountains, the soil properties of C, N and C/N have significant impacts on the genera Scutellospora, Paraglomus and unclassified in Archaeosporaceae, while the genera Glomus, Diversispora and Acaulospora are significantly affected by soil P and pH. It can be considered that altitude probably determines the presence of AMF communities by affecting edaphic properties. (4) Conclusions: There are abundant AMF associated with roots in the tropical montane rainforests of China. Furthermore, a high turnover of OTUs was found to exist between the mountains and at different altitudes, revealing diverse AMF community structures in tropical montane rainforests.

Arbuscular Mycorrhizal Fungi Community Dynamics and Functioning in Diff erent Rice Cultivation Systems

As a main component of soil microbiota arbuscular mycorrhizal fungi (AMF) play a benefi cial role in the agro-ecosystems. Introduction of AMF inoculum as a biofertilizer to the rice cultivation system is one of the environmentally healthy solutions that may increase crop productivity and yield, when compare to the non-AMF relationships. Within an ecosystem, both biotic and abiotic factors affect the diversity, distribution, and ecological role of AMF. Here we reviewed the effect of the variables including production area, environmental conditions, agricultural management systems, rice varieties, and different growth stages of the host on dynamics and structure of the AMF community mainly in the rice fi elds. Understanding of this co-relation is required to explore their future enrolment in agriculture. To ensure food security, identifi cation of all variables that may make indigenous AMF presence and active in different rice growing systems needs to be done in order to explore this specifi c fungus-root interaction.

Short Communication: Occurrence of arbuscular mycorrhizal fungi associated with Casuarina equisetifolia in saline sandy environment, North Sumatra, Indonesia

Abstract. Delvian, Hartanto A. 2022. Short Communication: Occurrence of arbuscular mycorrhizal fungi associated with Casuarina equisetifolia in saline sandy environment, North Sumatra, Indonesia. Biodiversitas 23: 2520-2525. Arbuscular mycorrhizal fungi (AMF) form a mutualistic association with plant roots to cope in the extreme environments including the saline and sandy soils in the coastal areas. In this study, the occurrence of AMF associated with Casuarina equisetifolia that has been planted for coastal rehabilitation located at Cermin Beach, North Sumatra was investigated including its abiotic-biotic interactions from topsoils (0-20 cm) to subsoils (20-80 cm). A total of 10 AM fungal morphotypes were documented with Glomeraceae as the dominant AM fungal taxa (9 morphotypes) and a Glomoid morphotype exists in all soil depths. The number of AMF spores decreased as soil depth increased following other environmental conditions such as pH, soil P availability and soil moisture based on the result of Pearson’s correlation test. The results showed a moderate-to-low level of biodiversity of AMF based on Shannon’s diversity index. The findings revealed the vertical distribution of AMF in a saline environment and supported the planting of C. equisetifolia which successfully recruited the indigenous AMF to form a symbiosis to thrive in the stressful environment.

Distribution of arbuscular mycorrhizal fungi in sugarcane rhizosphere from various agricultural management practices in Northeast, Thailand

Distribution of arbuscular mycorrhizal fungi in sugarcane rhizosphere from various agricultural management practices in Northeast, Thailand

Diverse and abundant arbuscular mycorrhizal fungi in ecological floating beds used to treat eutrophic water.

An increasing number of investigations have shown the universal existence of arbuscular mycorrhizal fungi (AMF) in aquatic ecosystems. However, little is known about the accurate distribution and function of AMF inhabiting aquatic ecosystems, especially ecological floating beds (EFBs), which are constructed for the remediation of polluted water bodies. In this study, we collected root samples of Canna generalis, Cyperus alternifolius, and Eichhornia crassipes from three EFBs on two eutrophic lakes in Wuhan, China. We aimed to investigate the resources and distribution of AMF in EFBs using Illumina Mi-seq technology. A total of 229 operational taxonomic units (OTUs) and 21 taxa from 348,799 Glomeromycota sequences were detected. Glomus and Acaulospora were the most dominant and second most dominant genera of AMF in the three EFBs, respectively. Different aquatic plant species showed varying degrees of AMF colonization (3.83-71%), diversity (6-103 OTUs, 3-15 virtual taxa), and abundance (14-57,551 sequences). Low AMF abundance, but relatively high AMF diversity, was found in C. alternifolius, which is usually considered non-mycorrhizal. This finding indicated the high accuracy of Illumina sequencing. Our results also revealed a lognormal species abundance distribution that was observed across AMF taxa in the three plant species. The AMF community composition was closely related to nitrogen and phosphorus contents. Overall, our data show that EFBs harbor diverse and abundant AMF communities. Additionally, the AMF community composition is closely related to the water quality of eutrophic lakes treated by the EFBs, indicating the potential application of AMF in plant-based bioremediation of wastewater. KEYPOINTS: • Aquatic plants in EFBs harbor diverse (229 OTUs) and abundant (348,799 sequences) AMF. • Different plant species host different taxa of AMF. Cyperaceae, originally considered non-mycorrhizal, may in fact be a variable mycorrhizal plant family. • The AMF community composition in EFBs is closely related to nutrient concentrations (nitrogen and phosphorus).

Global AM fungi are dominating mycorrhizal communities in a tropical premontane dry forest in Laipuna, South Ecuador

Tropical dry forests are an intricate ecosystem with special adaptations to periods of drought. Arbuscular mycorrhizal fungi (AMF) are essential for plant survival in all terrestrial ecosystems but might be of even greater importance in dry forests as plant growth is limited due to nutrient and water deficiency during the dry season. Tropical dry forests in Ecuador are highly endangered, but studies about AMF communities are scarce. We investigated the AMF community of a premontane semi-deciduous dry forest in South Ecuador during the dry season. We estimated AMF diversity, distribution, and composition of the study site based on operational taxonomic units (OTUs) and compared the results to those from the tropical montane rainforest and páramo in South Ecuador. OTU delimitation was based on part of the small ribosomal subunit obtained by cloning and Sanger sequencing. Nearly all OTUs were Glomeraceae. The four frequent OTUs were Glomus, and comparison with the MaarjAM database revealed these to be globally distributed with a wide range of ecological adaptations. Several OTUs are shared with virtual taxa from dry forests in Africa. Ordination analysis of AMF communities from the tropical dry and montane rainforests in South Ecuador revealed a unique AMF community in the dry forest with only few overlapping OTUs. Most OTUs that were found in both dry and rainforests and on the two continents were globally distributed Glomus.

Diversity and distribution of arbuscular mycorrhizal fungi in maize (Zea mays) cropping fields in South Kivu, Democratic Republic of Congo

Arbuscular Mycorhizal Fungi (AMF) occur naturally in agroecosystems and interact symbiotically with crops, facilitating nutrition. This study aimed at assessing the occurrence, abundance and diversity of AMF communities in the maize cropping system and their relation to soils properties in two agroecological zones in South Kivu, eastern DR Congo. Soil samples were collected from eight sites, with 4 sites in highland at 1400 to 2000 m altitude above sea level (in Katana, Kavumu, Mulamba and Mugogo) and four in the lowland at <1000 m (in Luberizi, Bwegera, Luvungi and Kamaniola). Spores were extracted from the field soils, morphologically identified and counted. AMF spores occurrence, abundances, species richness, and diversity were determined. A total of 38 AMF morphotypes distributed in 11 genera were obtained with the majority being from Gigasporaceae, Acaulosporaceae, and Glomeraceae families. This is the first report on the occurrence of these species in the eastern of DR Congo. Acaulospopra excavata, Acaulospopra bireticulata, Densitscutata erythropa, Funneliformis mosseae and Scutellospora pellucida were ubiquitous in all the agroecologies. Spores densities were higher in the highland with the highest recorded in Mulamba. Soil pH and phosphorus content influenced AMF distribution. The many different ubiquitous species indicate adaptation to a wide range of physicochemical environments and could reduce the cost of AMF inoculants production for the region. Maize agroecosystems are rich in AMF diversity and selection of appropriate fungal species from the Gigasporaceae, Acaulosporaceae and Glomeraceae as biofertilizer could contribute in improving crops production. Key words: Arbuscular mycorrhizal fungi, diversity, occurence, agroecological zones, maize, South Kivu.

Succession of endophytic fungi and arbuscular mycorrhizal fungi associated with the growth of plant and their correlation with secondary metabolites in the roots of plants

BackgroundTo decipher the root and microbial interaction, secondary metabolite accumulation in roots and the microbial community’s succession model during the plant’s growth period demands an in-depth investigation. However, till now, no comprehensive study is available on the succession of endophytic fungi and arbuscular mycorrhizal fungi (AMF) with roots of medicinal licorice plants and the effects of endophytic fungi and AMF on the secondary metabolite accumulation in licorice plant’s root.ResultsIn the current study, interaction between root and microbes in 1–3 years old medicinal licorice plant’s root and rhizospheric soil was investigated. Secondary metabolites content in licorice root was determined using high-performance liquid chromatography (HPLC). The composition and diversity of endophytic and AMF in the root and soil were deciphered using high-throughput sequencing technology. During the plant’s growth period, as compared to AMF, time and species significantly affected the diversity and richness of endophytic fungi, such as Ascomycota, Basidiomycota, Fusarium, Cladosporium, Sarocladium. The growth period also influenced the AMF diversity, evident by the significant increase in the relative abundance of Glomus and the significant decrease in the relative abundance of Diversispora. It indicated a different succession pattern between the endophytic fungal and AMF communities. Meanwhile, distance-based redundancy analysis and Mantel tests revealed root’s water content and secondary metabolites (glycyrrhizic acid, liquiritin, and total flavonoids), which conferred endophytic fungi and AMF diversity. Additionally, plant growth significantly altered soil’s physicochemical properties, which influenced the distribution of endophytic fungal and AMF communities.ConclusionsThis study indicated a different succession pattern between the endophytic fungal and AMF communities. During the plant’s growth period, the contents of three secondary metabolites in roots increased per year, which contributed to the overall differences in composition and distribution of endophytic fungal and AMF communities. The endophytic fungal communities were more sensitive to secondary metabolites than AMF communities. The current study provides novel insights into the interaction between rhizospheric microbes and root exudates.

Molecular Diversity and Distribution of Arbuscular Mycorrhizal Fungi at Different Elevations in Mt. Taibai of Qinling Mountain.

Arbuscular mycorrhizal fungi (AMFs) play a vital role in ecosystems, especially in ecosystem variability, diversity, and function. Understanding the AMF diversity, distribution, and their driver at different altitudinal gradients is a benefit for understanding the ecological function of AMF in mountain ecosystems. In this study, we explored the AMF molecular diversity and their distribution from 660 to 3,500 m a.s.l. in Mount Taibai of Qinling Mountains based on high-throughput sequencing technology. A total of 702 operational taxonomic units (OTUs) in 103 species of AMF are isolated from soil samples, which belong to 18 identified and 1 unidentified genus in 10 families. The fungi in the genus of Glomus is the most dominant, with the occurrence frequency of 100% and the relative abundance of 42.268% and 33.048% on the species and OTU level, respectively. The AMF colonization in root could be simulated by a cubic function with the change of altitudes with the peak and trough at a.s.l. 1,170 and 2,850 m, respectively. Further, AMF diversity indices including Sob, Shannon diversity, and Pielou evenness also showed the same cubic function change trends with increasing altitude at OTU and species levels. However, the average values of diversity indices at OTU level are always higher than these at the species level. Based on the OTU level, the highest and lowest values of Shannon and Pielou indices are observed at the altitudes of 1,400 and 2,800 m, respectively. The pattern of AMF community distribution in Mt. Taibai is driven by altitude with the characteristics of more abundance in the medium- to low-altitude than high-altitude areas. In general, abundant AMF molecular diversity and species exit in different elevations of Mt. Taibai, which indicate gradient changes with elevations.

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

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.

Diversity and distribution of arbuscular mycorrhizal fungi along a land use gradient in Terceira Island (Azores)

More knowledge of community composition of arbuscular mycorrhizal (AM) fungi in ecosystems in relation to habitat type and land use intensity is needed. We studied AMF in 106 soil samples from pristine natural forests and a gradient of disturbance including semi-natural and intensively managed pastures of Terceira, Azores. Altogether, 42 spore morphotypes were detected from eight AMF families, revealing different fungal community structures among the three land use types. Spore density was highest in native forests and lowest in intensively managed pastures, but fungal richness was highest in semi-natural pastures and lowest in native forests. No significant difference occurred between intensively managed pastures and native forests. Members of Acaulosporaceae and Glomeraceae were dominant in native forests, while fungi from Gigasporaceae and Claroideoglomeraceae were most abundant in semi-natural and intensively managed pastures respectively, indicating family-based ecological preferences. Rarefaction analysis revealed that pastures supported more diverse AMF communities than native forests, because in high elevation pristine forests, a few rare species dominate. It is therefore likely that more species would be found with increasing survey effort. Further research is needed to clarify the influence of land use type on AMF diversity and distribution in remote islands, and the role of native AMF on soil ecosystem processes and the spread of exotic plants.

Small-scale soil heterogeneity affects the distribution of arbuscular mycorrhizal fungal species in a hot-spot field in a Mediterranean site

Arbuscular mycorrhizal fungi (AMF) establish mutualistic symbioses with the roots of most plant species, playing a key role in crop productivity and ecosystem functioning. The characterization of local AMF genotypes assemblages is a prerequisite for the reproduction, both ex situ and on farm, of efficient native AMF communities, in order to improve soil quality and fertility through agricultural management and to use selected AMF as inoculants in sustainable agriculture. Contrasting evidences have been found by studies addressing the influence of different environmental drivers, among which geographical distance, on the diversity and composition of AMF communities in agricultural soils.In the present study, a Mediterranean “hot-spot” of AMF species richness was studied to assess whether AMF display a spatial structure at a local scale and whether their spore distribution is affected by soil variables. AMF distribution patterns were estimated by spore analysis, in 12 field plots, which were characterized for their chemical and physical variables. Plots were distributed along a transect across the field, and sampling points distances ranged from 4 to 102 m. While most taxa displayed an aggregated distribution, no significant spatial correlation was detected among AMF communities. On the contrary, AMF communities were significantly correlated with the entire set of soil variables, and with distinct soil characteristics, such as pH and total N, but not P. Among the most abundant taxa, Funneliformis geosporus, Septoglomus constrictum, Funneliformis mosseae, Ambispora granatensis and Glomus badium, were positively affected by total N, and Paraglomus occultum negatively affected by pH. Multiple regression analysis revealed that distribution of most AMF species was significantly related to nitrogen, clay, cation exchange capacity and pH. Multivariate (RDA) analysis confirmed results of multiple regression, with the best model selecting three soil variables (N, clay and pH). Variance partitioning analysis also showed that AMF distribution was mostly explained by environmental variables (36.4%) and by environmental variables spatial structure (16.4%). Overall, the results of this work revealed the importance of soil variables in shaping AMF community composition and spatial heterogeneity, within a site characterized by high AMF richness.