Arbuscular Mycorrhizal Fungi Species Richness Research Articles

Prairie restoration promotes the abundance and diversity of mutualistic arbuscular mycorrhizal fungi.

Predicting how biological communities assemble in restored ecosystems can assist in conservation efforts, but most research has focused on plants, with relatively little attention paid to soil microbial organisms that plants interact with. Arbuscular mycorrhizal (AM) fungi are an ecologically significant functional group of soil microbes that form mutualistic symbioses with plants and could therefore respond positively to plant community restoration. To evaluate the effects of plant community restoration on AM fungi, we compared AM fungal abundance, species richness, and community composition of five annually cultivated, conventionally managed agricultural fields with paired adjacent retired agricultural fields that had undergone prairie restoration 5-9 years prior to sampling. We hypothesized that restoration stimulates AM fungal abundance and species richness, particularly for disturbance-sensitive taxa, and that gains of new taxa would not displace AM fungal species present prior to restoration due to legacy effects. AM fungal abundance was quantified by measuring soil spore density and root colonization. AM fungal species richness and community composition were determined in soils and plant roots using DNA high-throughput sequencing. Soil spore density was 2.3 times higher in restored prairies compared to agricultural fields, but AM fungal root colonization did not differ between land use types. AM fungal species richness was 2.7 and 1.4 times higher in restored prairies versus agricultural fields for soil and roots, respectively. The abundance of Glomeraceae, a disturbance-tolerant family, decreased by 25% from agricultural to restored prairie soils but did not differ in plant roots. The abundance of Claroideoglomeraceae and Diversisporaceae, both disturbance-sensitive families, was 4.6 and 3.2 times higher in restored prairie versus agricultural soils, respectively. Species turnover was higher than expected relative to a null model, indicating that AM fungal species were gained by replacement. Our findings demonstrate that restoration can promote a relatively rapid increase in the abundance and diversity of soil microbial communities that had been degraded by decades of intensive land use, and community compositional change can be predicted by the disturbance tolerance of soil microbial taxonomic and functional groups.

Heterogeneity in Arbuscular Mycorrhizal Fungi and Plant Communities of the Brazilian Cerrado, Transitional Areas toward the Caatinga, and the Atlantic Forest.

The Cerrado is the most diverse tropical savanna worldwide and the second-largest biome in South America. The objective of this study was to understand the heterogeneity and dynamics of arbuscular mycorrhizal fungi (AMF) in different types of natural Cerrado vegetation and areas that are transitioning to dryer savannas or tropical rainforests and to elucidate the driving factors responsible for the differences between these ecosystems. Twenty-one natural sites were investigated, including typical Cerrado forest, typical Caatinga, Atlantic Rainforest, transitions between Cerrado and Caatinga, Cerrado areas near Caatinga or rainforest, and Carrasco sites. Spores were extracted from the soils, counted, and morphologically analyzed. In total, 82 AMF species were detected. AMF species richness varied between 36 and 51, with the highest richness found in the area transitioning between Cerrado and Caatinga, followed by areas of Cerrado close to Caatinga and typical Cerrado forest. The types of Cerrado vegetation and the areas transitioning to the Caatinga shared the highest numbers of AMF species (32-38). Vegetation, along with chemical and physical soil parameters, affected the AMF communities, which may also result from seasonal rainfall patterns. The Cerrado has a great AMF diversity and is, consequently, a natural refuge for AMF. The plant and microbial communities as well as the diversity of habitats require urgent protection within the Cerrado, as it represents a key AMF hotspot.

EFFET DE LORPAILLAGE SUR LABONDANCE ET LA DIVERSITE DES ESPECES DE CHAMPIGNONS MYCORHIZIENS ARBUSCULAIRES DANS LA REGION CENTRALE DU TOGO

Gold mining has a negative impact on the soil include microorganisms such as Arbuscular Mycorrhizal Fungi (AMF). The AMF form associations with plants by improving their development However, the effect of gold mining on Arbuscular Mycorrhizal Fungi (AMF) living in its soils is poorly understood.The objective of this study was to characterize the effect of gold mining on the abundance and diversity of AMF species in the Central region of Togo. The AMF were extracted by wet sieving from 200g of soil samples taken directly from four types of soil, Gold Soil (SA), Washed Gold Soil (SAL), Soil Under Corn Cultivation (SSCM) and the Soil Under Natural Vegetation (SSVN). The diversity of AMF was determined by diversity indices. The results showed that SA, SSCM and SSVN had significantly higher AMF fungal spores densities (p < 0.05) than SAL. AMF species richness was generally lower in SAL (12 species out of a total of 30 species identified). A total of 30 AMF species classified into 16 genera, in 9 families (AcaulosporaceaeAmbisporaceae, Archaeosporaceae, Gigasporaceae, Claroideoglomeraceae, Dentiscutataceae, Diversisporaceae, Glomeraceae, Paraglomeraceae) were identified. The most frequent species were Acaulosporascorbiculata, Acaulospora sp., Entrophosporainfrequens, Gigaspora gigantea, Claroideoglomusetunicatum. The most abundant species were Acaulosporascorbiculata, Acaulosporasp., Entrophosporainfrequens, ClaroideoglomusEtunicatum, Glomus clavisporum, and Rhizophagusintraradices. The biological diversity indices (Shannon and Pielou equitability) revealed a significant difference (P < 0.05) between the different types of soils studied. The density of the spores as well as their diversityvary as follows: SAL<SA< SSVN< SSCM. The soils of the study area contain a great natural wealth of AMF species, but this natural wealth is significantly affected by gold panning. The native AMF found in these areas could be used for the ecological restoration of degraded gold panning areas.

Rhizoglomus variabile and Nanoglomus plukenetiae, Native to Peru, Promote Coffee Growth in Western Amazonia.

Coffee (Coffea arabica) is among the world's most economically important crops. Coffee was shown to be highly dependent on arbuscular mycorrhizal fungi (AMF) in traditionally managed coffee plantations in the tropics. The objective of this study was to assess AMF species richness in coffee plantations of four provinces in Perú, to isolate AMF isolates native to these provinces, and to test the effects of selected indigenous AMF strains on coffee growth. AMF species were identified by morphological tools on the genus level, and if possible further to the species level. Two native species, Rhizoglomus variabile and Nanoglomus plukenetiae, recently described from the Peruvian mountain ranges, were successfully cultured in the greenhouse on host plants. In two independent experiments, both species were assessed for their ability to colonize coffee seedlings and improve coffee growth over 135 days. A total of 35 AMF morphospecies were identified from 12 plantations. The two inoculated species effectively colonized coffee roots, which resulted in 3.0-8.6 times higher shoot, root and total biomass, when compared to the non-mycorrhizal controls. R. variabile was superior to N. plukenetiae in all measured parameters, increasing shoot, root, and total biomass dry weight by 4.7, 8.6 and 5.5 times, respectively. The dual inoculation of both species, however, did not further improve plant growth, when compared to single-species inoculations. The colonization of coffee by either R. variabile or N. plukenetiae strongly enhances coffee plant growth. R. variabile, in particular, offers enormous potential for improving coffee establishment and productivity. Assessment of further AMF species, including species from other AMF families should be considered for optimization of coffee growth promotion, both alone and in combination with R. variabile.

Characterization of the arbuscular mycorrhizal fungal community associated with rosewood in threatened Miombo forests.

Understanding the dynamics of arbuscular mycorrhizal fungi (AMF) in response to land use change is important for the restoration of degraded forests. Here, we investigated the AMF community composition in the roots of Pterocarpus tinctorius sampled from agricultural and forest fallow soils rich in aluminum and iron. By sequencing the large subunit region of the rRNA gene, we identified a total of 30 operational taxonomic units (OTUs) in 33 root samples. These OTUs belonged to the genera Rhizophagus, Dominikia, Glomus, Sclerocystis, and Scutellospora. The majority of these OTUs did not closely match any known AMF species. We found that AMF species richness was significantly influenced by soil properties and overall tree density. Acidic soils with high levels of aluminum and iron had a low mean AMF species richness of 3.2. Indicator species analyses revealed several AMF OTUs associated with base saturation (4 OTUs), high aluminum (3 OTUs), and iron (2 OTUs). OTUs positively correlated with acidity (1 OTU), iron, and available phosphorus (2 OTUs) were assigned to the genus Rhizophagus, suggesting their tolerance to aluminum and iron. The results highlight the potential of leguminous trees in tropical dry forests as a reservoir of unknown AMF species. The baseline data obtained in this study opens new avenues for future studies, including the use of indigenous AMF-based biofertilizers to implement ecological revegetation strategies and improve land use.

Arbuscular Mycorrhiza Symbiosis as a Factor of Asteraceae Species Invasion

Invasive weeds of the Asteraceae family are widespread in the world. Arbuscular mycorrhiza (AM) is one of the main factors contributing to the successful distribution of these species that is most clearly manifested in the subfamily Asteroideae. The benefits of plant-AMF symbiosis are most significant under unfavorable biotic and abiotic conditions. The specificity of the relationship between arbuscular mycorrhizal fungi (AMF) communities and plants and is determined at the presymbiotic stage. The AMF colonization level is higher in invasive species than in native ones, but AMF communities associated with Asteraceae invasive species are less diverse. AMF communities of Asteraceae invaders often include fewer common species (e.g., species belonging to Diversisporales). Invaders also reduce native AMF species richness in new areas. Arbuscular mycorrhizal fungi can form mycorrhizal networks that allow the redistribution of nutrients in plant communities. The most significant influence of AMF associated with invasive Asteraceae plants is seen in the formation of soil and rhizosphere microbiota, including the suppression of beneficial soil bacteria and fungi. This review could be useful in the development of practical recommendations for the use of AMF-based fertilizers.

Vascular plant and cryptogam abundance as well as soil chemical properties shape microbial communities in the successional gradient of glacier foreland soils

In the glacier forelands, microbes play a fundamental role in soil development and shaping the vegetation structure. Such ecosystems represent various stages of soil development and are, therefore, an excellent place to study the interrelationship between soil, plants, and microorganisms. The aim of the study was to assess the effects of vegetation and soil physicochemical properties developing after glacier retreat on soil microbial communities. Specifically, abundance, species richness and the composition of arbuscular mycorrhizal fungi (AMF), as well as microbial biomass and community structure in soils were compared between plots established in 800-meter transects of three glacier forelands in northern Sweden. The cover of vascular plants and cryptogams, soil C content, AMF spore density and species richness, AMF biomass indicators, total microbial biomass, and bacterial phospholipid fatty acids (PLFA) were significantly and positively related to the distance from the glacier terminus. On the other hand, macronutrient concentrations and pH decreased along with increasing distance. No significant impact of the distance from the glacier terminus on the ratio fungal/bacterial PLFA was observed. Moreover, we found a significant effect of both glacier and the distance from the glacier terminus on the microbial community structure. AMF species richness and spore density in the glacier forelands were generally low, which is probably due to a limited supply of inoculum in primary successional ecosystems. Most microbial biochemical markers and AMF parameters were positively associated with the number of arbuscular mycorrhizal plant species and vascular plant and lichen cover as well as C content in soil, whereas negatively with soil macronutrients and pH. This could be related to an increase in plant cover and a decrease in soil nutrient levels as plant succession progresses. Our results showed that vegetation, soil C content, and microbial communities are interlinked and exhibit concordant patterns along successional gradients.

Host plant richness and environment in tropical forest transformation systems shape arbuscular mycorrhizal fungal richness.

Transformation of tropical lowland rain forests into rubber tree and oil palm plantations is the cause of massive loss of vegetation diversity. The consequences for associated mycorrhizal fungi are not fully understood. We hypothesized that generalist arbuscular mycorrhizal fungi are resistant to removal of host species richness and that forest conversion to oil palm and rubber leads to loss of arbuscular mycorrhizal fungal (AMF) species with host preferences. Plant identities and AMF species were determined by molecular barcoding of 112 roots collected in three land-use systems (rain forest, rubber tree and oil palm plantation) in two landscapes on Sumatra (Indonesia), a world hotspot of forest transformation. The collected roots were from 43 forest plant species, in addition to rubber trees and oil palms. We detected 28 AMF species of which about 75% were present in forest trees and 25% shared among the land use systems. Only one AMF species present in plantation roots was not detected in the analyzed forest roots. Host specificity of arbuscular mycorrhizal fungi was not detected. Oil palm and rubber tree roots exhibited a strong reduction in AMF richness compared with roots from rainforests and were differentiated by soil resources. On basis of an individual root, oil palm had a lower AMF species richness than forest or rubber tree roots. Our results demonstrate that tropical AMF communities are shaped by two mechanisms: (i) root habitat diversity as the result of plant diversity and (ii) habitat properties as the result of plant traits or environmental conditions and management. Collectively, deterioration of habitat diversity and properties exacerbates impoverishment of AMF assemblages.

Rehabilitation promotes rapid recovery of arbuscular mycorrhizal fungi in iron mining areas

Arbuscular mycorrhizal fungi (AMF) perform important ecological functions in the rehabilitation of degraded areas, acting through several mechanisms, such as the production of glomalin-related soil proteins (glomalin), which act as cementing agents and nutritional reserves and sequester carbon in soil. The aim of the present study was to determine whether a short rehabilitation time influenced the soil AMF community diversity and glomalin production in areas undergoing rehabilitation after iron mining. We analyzed the number of spores, mycorrhizal colonization, AMF species richness, and concentrations of easily extractable and total glomalin-related soil proteins. Species richness was reduced by approximately 50 % after mining activity. However, after the initial rehabilitation of degraded areas, we observed an increase in the number of spores, colonization, and AMF species. Families Glomeraceae and Acaulosporaceae were considered dominant in the studied areas. Glomus sp.1 and Acaulospora mellea were the most frequent morphotypes. The relationship between glomalin and the levels of dissolved organic carbon, total carbon, and total nitrogen in the soil was found to be an interesting and easily interpretable parameter of the influence of AMF on the storage of organic matter in the soil, indicating the degree of equilibrium and/or recovery of revegetated environments. Rehabilitation, even in early stages, favored improvements in AMF status and provided increases in total glomalin-related soil protein production, which may have contributed to the enrichment of carbon and nitrogen in the soil. These characteristics are indicative of the success of the rehabilitation actions carried out in these areas after mining activity.

Effects of no-tillage and biologically-based organic fertilizer on soil arbuscular mycorrhizal fungal communities in winter wheat field

Communities of arbuscular mycorrhizal fungi (AMF) in soil are impacted by agricultural management, which in turn influences crop growth and yield. Yet the combined effects of tillage and fertilization practices upon AMF communities are still poorly understood. This study investigated the interactive effects of tillage (no-tillage and conventional tillage) and fertilization (no-fertilization and biologically based organic fertilization) factors on AMF community structure and yield of winter wheat field. The five-year field experiment was conducted in Longde County, Ningxia, China. Results indicated that no-tillage significantly increased the species richness, evenness, and diversity of soil AMF, whereas bio-organic fertilization was less influential. Under no-tillage, bio-organic fertilization marginally increased the richness and diversity of AMF species; however, under conventional tillage this effect was inversed. Glomus, Claroideoglomus, and Paraglomus AMF genera dominated under no-tillage combined with bio-organic fertilization. No-tillage increased the relative abundance of Glomus, while bio-organic fertilization increased that of Claroideoglomus. Redundancy analysis revealed that total nitrogen and available phosphorus were the most important soil variables related to the diversity and community composition of AMF. The yield of winter wheat was negatively correlated with AMF diversity and positively correlated with Glomus abundance. This study suggests that, compared to single conservation agricultural practices, combining no-tillage with bio-organic fertilization may further improve the benefits of soil AMF for winter wheat crops. However, under low nitrogen and phosphorus inputs, conventional tillage can accelerate the mineralization of organic matter and increase the availability of soil nutrients, thereby improving wheat yield.

Seasonal variation of arbuscular mycorrhizal fungi in ecotone forests of the northern region of Brazilian Amazonia

The ecotone forests in the northern region of Brazilian Amazonia are important areas representing transition zones between forest and non-forest ecosystems. These areas have soils nutrient-poor that poorly drain. Under these environmental conditions, Peltogyne gracilipes (Leguminoseae), an endemic tree species, can form natural monodominant forests. Here, we assessed the arbuscular mycorrhizal fungi (AMF) community in three forest types on the eastern side of Maracá Island and the relationship of these microorganisms with the monodominance of P. gracilipes. In this study, soil samples were collected in two seasons (dry and rainy). The samples were collected in 9 plots, in rich areas, poor areas and areas without P. gracilipes. Soil samples were evaluated for chemical and particle size analysis, spore density and morphology, and identification of AMF. AMF species were identified using two approaches: spores collected in the field and trap cultures. Eighteen and 13 AMF species were identified in the dry and rainy seasons, respectively, for spores extracted from the field. Six total species were detected exclusively in trap cultures in the dry season. AMF communities were co-dominated by members of the Gigasporaceae, Acaulosporaceae and Glomeraceae families. Redundancy analyses indicated that several soil attributes, such as pH, Fe, Mg, and sand content associated with the AMF species richness in both seasons. We conclude that the ecotone forests in the eastern region of Maracá Island are home to important richness and diversity of AMF species and that various soil factors influence the composition of the AMF community in this ecosystem.

Effect ofElymus nutans on the assemblage of arbuscular mycorrhizal fungal communities enhanced by soil available nitrogen in the restoration succession of revegetated grassland on theQinghai‐TibetanPlateau

AbstractThe succession of arbuscular mycorrhizal fungi (AMF) communities during ecosystem development has received widespread attention, but the ecological mechanism that drives the succession of AMF communities during the restoration process in alpine meadow ecosystems remains unclear. Here, we treated ‘Black Beach’ (severely degraded alpine meadow) as the baseline for restoration (0 year), and selected the revegetated grassland ofElymus nutanswith different planting times (3, 7, 10, and 14 years) to analyze the species composition of the AMF community in mixed roots (at the whole‐plant‐community scale) and inE. nutansroots (at the single‐plant‐species scale). A total of 46 AMF phylotypes (mixed roots: 44;E. nutansroots: 46) were identified in both root systems, predominantly belonging to Glomeraceae. AMF species richness showed a single‐peak curve change across the restoration time and reached its peak at 3 years in both root systems. In mixed roots, the soil available nitrogen not only directly changed the AMF species composition but also indirectly changed the AMF species composition through plant richness. In theE. nutansroots, only the soil available nitrogen drove changes in AMF species composition through changes in plant richness. Our results indicate thatE. nutans, a key species in the restoration process of revegetated grassland, can enhance its regulation to assemble the AMF community through soil available nitrogen at the two research scales, suggesting that the scientific management of soil nitrogen availability during restoration succession could strengthen the mutual symbiosis of ‘plant‐AMF,’ thereby retarding the occurrence of secondary degradation of revegetated grassland.

Wildfire does not affect spore abundance, species richness, and inoculum potential of arbuscular mycorrhizal fungi (Glomeromycota) in ferruginous Canga ecosystems

Canga ecosystems develop over superficial iron crusts with shallow and nutrient-poor soils. Under these conditions, arbuscular mycorrhizal fungi (AMF) play an important role in helping plants to overcome abiotic and biotic stresses. Canga can suffer periodic burning and yet it is unknown what the impacts of fire are to AMF communities. We aimed to compare AMF in Canga areas affected by burning (BC) with those with no previous history of burning (NC). We compared AMF species composition, spore numbers, species richness, and mycorrhizal inoculum potential. The total number of spores, AMF species richness and mycorrhizal colonization measured in the infectivity bioassay were not significantly different between areas. A total of 23 species in 10 genera were recovered, with most species belonging to Gigasporaceae and Acaulosporaceae. BC and NC shared 52 % of AMF species. Gigaspora albida, Gigaspora gigantea, and Dentiscutata heterogama sporulated exclusively in trap cultures. We concluded that AMF spore communities were not affected by burning in Canga soils as measured by spore abundance, species richness and infectivity. Our data contribute to the inventory of soil biodiversity associated with Canga, a high biodiverse and threatened Brazilian ecosystem.

Fungal root colonization and arbuscular mycorrhizal fungi diversity in soils of grasslands with different mowing intensities

Grasslands are among the most dynamic and threatened plant communities, largely due to their dependence on management that has changed in recent decades. The intensity of human-induced disturbances (primarily removal of plant biomass by various methods) has decreased, leading to changes in plant species composition and declines in plant diversity in these communities. So far, no studies have shown how mowing affects fungal communities in both roots and soils and their relation with plant community parameters and soil chemical properties in different grassland types. We thus compared the impact of mowing intensity (low, moderate, high) on root colonization by common root-inhabiting fungi, namely arbuscular mycorrhizal fungi (AMF), dark septate endophytes (DSE), and Olpidium spp., as well as on AMF spore number, species richness and composition in soils for three seasons (spring, summer, autumn), in grasslands differing in soil moisture (wet, moderately wet, and dry). Mowing intensity had no effect on the fungal root colonization. The number of AMF spores and species, and AMF species composition did not differ between types of management as well. However, most of the fungal parameters in roots and soils varied across the types of grassland and/or seasons. Our results suggest that AMF, DSE, and Olpidium spp. colonization of plants as well as AMF diversity in soils in the studied grasslands are resilient to the mowing disturbance. This may be due to the low impact of the management on plant species richness and soil chemical properties, as well as the adaptation of these fungal communities to recurrent human-induced disturbances in semi-natural habitats.

Arbuscular mycorrhizal fungal community responses to drought and nitrogen fertilization in switchgrass stands

Anthropogenic global change is increasing the severity and frequency of abiotic stresses such as drought that are likely to affect soil communities. Arbuscular mycorrhizal fungi (AMF) play important roles in many soil processes, so it is important to understand how drought affects AMF biodiversity. This is especially relevant in agricultural systems where crops rely on AMF associations for water and nutrient uptake, and where management decisions such as crop selection and fertilizer application may influence how the AMF community responds to drought. In this study, we examined the effects of reduced precipitation and nitrogen fertilization on AMF richness, community composition, and root and soil colonization in monocultures of two cultivars of switchgrass (Panicum virgatum) grown for bioenergy feedstock. We conducted a two-year field experiment using rain-out shelters to manipulate precipitation in mature stands of switchgrass growing in a long-term nitrogen fertilization (0 or 56 kg N ha−1) experiment at the W.K. Kellogg Biological Station Long-Term Ecological Research site in Michigan, USA. We expected that AMF richness and colonization would decrease due to drought, as predicted by the stress exclusion hypothesis. Contrary to our expectations, we found that drought stress increased AMF species richness in fertilized plots by 15%; there was no effect of drought on AMF richness in unfertilized plots. Drought also significantly altered AMF community composition, primarily due to increases in Rhizophagus taxa abundance, and reduced AMF root colonization in switchgrass by 6%. We also found variation in AMF richness and colonization across switchgrass cultivars as well as sampling dates. The changes in AMF richness and composition that we observed in this study may have implications for perennial bioenergy feedstock selection and management as changes in AMF communities may feedback to affect host plants.

The effects of long-term warming on arbuscular mycorrhizal fungal communities depend on habitat type on the Qinghai-Tibet Plateau

Arbuscular mycorrhizal fungi (AMF) are widespread root-associated microorganisms that participate in many ecosystem processes. However, the response of AMF communities to global warming still remains poorly understood, especially in high-altitude regions. This study investigated the responses of AMF communities to 17-year experimental warming with open top chambers in two habitat types (i.e., shrubland and meadow) of the alpine meadow ecosystem of the Qinghai–Tibet Plateau. For this, 454-pyrosequencing was used and the main ecological processes that structure AMF communities were inferred based on distributions of species abundance and phylogenetic patterns. A total of 110 different AMF phylotypes (shrubland habitat: 102; meadow habitat: 91) were identified in both habitats, predominantly belonging to Glomeraceae. Eighty AMF phylotypes were found in both habitats, and phylotypes affiliated with Acaulosporaceae and Archaeosporaceae were only found in the shrubland habitat. Warming did not affect AMF diversity or community composition in the shrubland habitat; however, in the meadow habitat, warming caused a decline of AMF species richness by 45.6%. Moreover, the taxon composition of AMF communities was changed via the negative influence of root biomass in the meadow habitat. Mandelbrot, based on the niche process, was the best-fitting model for all fungal data sets in both habitats, indicating that fungal community dynamics under warming treatments matched niche-based processes in both habitats. Moreover, the phylogenetic structure of AMF communities was always phylogenetically clustered regardless of warming in the shrubland habitat. However, the phylogenetic structure changed from phylogenetic clustering of the control treatment to random of warming treatment in the meadow habitat. This suggests that in the shrubland habitat, warming does not change the central ecological process that structures AMF communities, but rather, leads to the transformation of the central process from environmental filtration to the neutralization of habitat filtration and competition exclusion in the meadow habitat. In summary, these results indicate that the effect of long-term warming on the assemblage of AMF communities depends on the habitat type. This illustrates that maintaining a high habitat type complexity is conducive for the response of alpine meadow ecosystems to climate warming.

Intraspecific plant interaction affects arbuscular mycorrhizal fungal species richness

It is well established that mycorrhizal symbiosis can affect plant-plant interactions. On the other hand, how intraspecific plant interactions influence communities of arbuscular mycorrhizal fungi (AMF) is still very poorly understood. We applied 454 pyrosequencing to determine the responses of AMF communities to intraspecific shoot and root interactions using Medicago sativa L. as host plant. We found that intraspecific plant interaction caused significant variation in the structure of the AMF community assessed from roots but not from soil. Intraspecific root system interaction resulted in significantly elevated AMF species richness, greater total mycorrhizal and arbuscular colonization, and a larger root:shoot ratio compared to plants experiencing intraspecific shoot interaction or no interaction. Intraspecific shoot interaction resulted in significantly depressed AMF species richness. Our results support two hypotheses. The first is that increased AMF species richness in plants experiencing intraspecific root interaction originates from competitive release provided by high root density. The second is that shoot interaction leads to reduced allocation to root systems, increasing the stringency with which host plants selectively reward the most cooperative fungi. Because intraspecific interactions among host plants can influence the structure of their AMF community, interactions among species in complex plant communities may influence AMF community structure in addition to a plant diversity effect.

The impact of beech and riparian forest herbaceous plant species with contrasting traits on arbuscular mycorrhizal fungi abundance and diversity

The impact of forest herbaceous plant species identity on arbuscular mycorrhizal fungi (AMF) communities in relation to vegetation and soil chemical properties has rarely been studied in temperate forests. We thus compared abundance and diversity of AMF in two deciduous forests, in the plots with herbaceous plant species of contrasting traits (morphology, phenology, reproduction, and ecology), including Allium ursinum and Dentaria enneaphyllos in a beech forest, as well as Aegopodium podagraria and Ficaria verna in a riparian forest. Plots with a mix of herbaceous plant species and bare soil were also studied. We found low values of AMF root colonisation degrees in both forests. In total, the spores of only 13 AMF species were detected; 12 species occurred in the riparian forest, whereas 6 were found in the beech forest. AMF species composition differed between forest types. Higher AMF root colonisation degrees and soil concentrations of PLFA 16:1ω5 AMF structural lipid marker were found in the riparian forest. There were no differences between the plots in AMF abundance and species richness in both forest soils. With regard to environmental variables, the number of arbuscular mycorrhizal (AM) tree species, plant cover, moisture, the concentrations of C, Ca, K, Mg, and N had, in general, a positive effect on AMF abundance in soils. We showed that despite AMF ubiquity, these fungi can be present at low densities in some habitats, such as beech and riparian forests. Higher AMF abundance and diversity in the riparian forest were probably related to larger numbers of AM tree and herbaceous plant species in this forest. Although the herbaceous plant species had contrasting traits, they had little effect on AMF abundance and diversity.

Arbuscular mycorrhizal status of Erythrina brucei in different land use types in Ethiopia

Erythrina brucei is a leguminous tree commonly used in agro-forestry practices in southern and southwestern Ethiopia. It has desirable agro-forestry attributes that make it a good candidate for agro-forestry systems. However, there is a scarcity of information regarding species diversity and spore density of arbuscular mycorrhizal fungi (AMF) associated with E. brucei growing in different land use types. Therefore, this study was initiated to determine species diversity and richness in trap cultures of AMF associated with E. brucei growing in different geographic locations in various land use types of Ethiopia. Soil samples were collected from various E. brucei growing areas with different land use patterns. Trap culture was established using a portion of each soil sample by planting E. brucei as the host plant. AMF spore extraction was carried out in field and trap culture soils, and AMF species identification was done using spore morphology. Erythrina brucei root colonization with AMF structures was studied using trap culture, and AMF spore density in both field and trap culture soil samples was determined. A total of 11 AMF genera and 33 AMF species were recovered. The highest number of genera was recovered from forest land use type at Rebu Gebeya, followed by Adiskdam, live fence land use type. Glomus and Acaulospora were the dominant AMF genera covering 73% of the samples and contained 10 and 9 AMF species, respectively. All the soil samples contained indigenous AMF spore populations regardless of their origin and land use types. The highest mean AMF spore density in a field soil sample was recorded at a farmland in Bodite (280 spores 100 g−1 of dry soil), while the lowest was from Hossana (172 spores 100 g−1of dry soil). However, the highest mean AMF spore density in trap culture was detected from a farm land at Humbo (715 spores 100 g−1 of dry soil) and the lowest from Dhakallo (217 spores 100 g−1 of dry soil). Direct extraction of AMF from field soil samples showed lesser AMF spore density compared with trap culture in the same soil sample. All E. brucei root segments were colonized with the AMF structures, and the colonization status ranged from 34.4% to 49.1%. Both geographic location and land use type significantly affected AMF species richness (p < 0.05). Undisturbed land use types were characterized by high species richness. The soil pH and available phosphorus were negatively correlated to AMF spore density (p < 0.05), but AMF root colonization did not show any significant correlation. Moreover, significant correlations were also not observed between spore number and root colonization, and available phosphorus and root length colonization. We conclude that diverse and dominant AMF genera inhabited the rhizosphere of E. brucei, which can be used for the enhancement of host plant growth. To explore AMF species diversity and richness across geographic location and land use types in detail enhanced area coverage and the combination of both direct field soil and trap culture techniques are recommended.

Biocrusts inside and outside of Mimosa luisana resource islands as reservoirs of arbuscular mycorrhizal fungi in a Mexican semiarid ecosystem

Background: Arbuscular mycorrhizal fungi (AMF) and biocrusts (BC), occur inside and outside Mimosa luisana resource islands (M. luisana-RI) at the Tehuacán-Cuicatlán Valley, Puebla-Oaxaca, Mexico.&#x0D; Objectives: To determine: 1) Whether there are AMF within biocrusts, 2) The abundance and richness of AMF, and 3) The potential of AMF propagation in BC and soil below BC inside (BC-RI, soil-BC-RI) and outside (BC-ORI, soil-BC-ORI) M. luisana-RI, and open areas (OA), in the rainy (September 2011) and dry (May 2012) seasons.&#x0D; Methods: AMF were extracted of biocrusts and soil samples collected inside and outside M. luisana-RI and OA, in both seasons. Spore abundance and species richness, as well as potential propagation of AMF were determined in laboratory and greenhouse.&#x0D; Results and Conclusions: Biocrusts inside and outside M. luisana-RI form reservoirs of AMF spores and species richness (12 spp.), and act as “shields” protecting AMF compared with OA (5 spp.). Seasonal changes in the AMF composition within the biocrusts and the soil suggest that the availability of water drives AMF assemblages. The AM fungal spores in BC-RI and BC-ORI have a high potential of propagation; however, the BC-ORI by buffering the loss of AMF in soil-BC-ORI, they form mycorrhizal inocula within the soil.