Enkianthus campanulatus (Ericaceae) is commonly associated with arbuscular mycorrhizal fungi

Enkianthus is the most basal extant genus in the phylogeny of ericaceous plants. Its members harbor arbuscular mycorrhiza (AM)-like hyphal structures in their roots but, as yet, no study has surveyed the AM fungal species component. Roots from six species of Enkianthus were collected from five distantly located sites in Japan. Intracellular hyphal coils were observed in the root cortical cells of all species. Fungal DNA sequences of the small subunit ribosomal RNA gene were obtained from 73 of 75 segments of Enkianthus campanulatus roots by PCR using either AML2 or NS31/AM1primer pairs. Results indicated that all E. campanulatus trees were extensively associated with Glomus spp. A phylogenetic analysis showed that 71 root segments harbored fungi belonging to Glomus group A. Among eight delineated clades, seven did not nest with any known AM fungal species. One clade was detected in all roots at all sites at relatively high frequencies, but the rest were detected sporadically at each site. The placement of sequences from distantly located sites into a single clade without known AM fungal species suggests the common association of E. campanulatus with particular AM fungal taxa.     

Defoliation effects on the community structure of arbuscular mycorrhizal fungi based on 18S rDNA sequences

The effects of defoliation on arbuscular mycorrhizal (AM) associations in the field were investigated in terms of the community structure of AM fungi colonizing roots of grassland plants; the carbohydrate balance of the host plants was also determined. We focused on two plant species dominating Japanese native grasslands: the grazing-intolerant species Miscanthus sinensis and the grazing-tolerant species Zoysia japonica. Community structures of AM fungi were determined from 18S rRNA gene sequences. The dominant fungal group in both plant species was the Glomus clade, which was classified into several phylogenetic groups based on genetic distances and topology. In Miscanthus roots, the Glomus-Ab, Glomus-Ac, and Glomus-Ad groups were detected almost equally. In Zoysia roots, the Glomus-Ab group was dominant. Defoliation effects on the community structure of AM fungi differed between the plant species. In Miscanthus roots, the percentage of root length colonized (%RLC) by the Glomus-Ac and Glomus-Ad groups was significantly reduced by defoliation treatment. On the other hand, AM fungal group composition in Zoysia roots was unaffected by defoliation except on the last sampling date. Decreased %RLC by Glomus-Ac and Glomus-Ad coincided with decreased non-structural carbohydrate (NSC) levels in host plants; also, significant positive correlations were found between the %RLC and some NSC levels. On the other hand, the %RLC by Glomus-Ab in both plant species was unaffected by the NSC level. These results suggest that AM fungal groups have different carbohydrate requirements from host plants.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00572-003-0286-x     

Arbuscular mycorrhizal fungal community structures differ between co-occurring tree species of dry Afromontane tropical forest, and their seedlings exhibit potential to trap isolates suited for reforestation

The diversity of arbuscular mycorrhizal (AM) fungi and their broad or narrow association with distinct plant species in natural environments are crucial information in the understanding of the ecological role of AM fungi on plant co-existence. This knowledge is also needed for appropriate mycorrhization of nursery-grown seedlings for forestation efforts. Here, we report results from comparative studies on three co-occurring indigenous tree species of the dry Afromontane forests of Ethiopia and their seedlings grown under controlled conditions in soil collected from the sites. AM fungal SSU rDNA fragment was amplified and sequenced from mycorrhizas of adult plants and seedlings of Olea europaea subsp. cuspidata and Prunus africana, and from Podocarpus falcatus seedlings. AM fungal identity, diversity and community structure were analyzed based on sequence types defined by the NS31-AM1 SSU rDNA fragment similarity in order to compare with data from other habitats. A total of 409 sequences, grouped in 32 sequence types, belonging to Glomeraceae, Diversisporaceae and Gigasporaceae were found. Some sequence types are close to the widespread Glomus intraradices, G. hoi, G. etunicatum, G. cf. etunicatum and Gigaspora margarita. However, the majority (59%) of sequence types are so far specific for the sites including 11 new types when compared with previous data from the same area. The AM fungal community associated with adult plants, including data previously obtained from adult Podocarpus falcatus seedlings, and seedlings of a host species differed significantly, where seedlings trapping a surprising large number of native fungi. AM fungal community structure also differed significantly between host species and sites, respectively. The results confirm previous results from the same area indicating distinct fungal communities associated with the diverse tree species and suggests the potential of these indigenous tree seedlings to trap a wide range of AM fungi appropriate for successful afforestation.     

Preferential Colonization of Solanum tuberosum L. Roots by the Fungus Glomus intraradices in Arable Soil of a Potato Farming Area

The symbiosis between plant roots and arbuscular mycorrhizal (AM) fungi has been shown to affect both the diversity and productivity of agricultural communities. In this study, we characterized the AM fungal communities of Solanum tuberosum L. (potato) roots and of the bulk soil in two nearby areas of northern Italy, in order to verify if land use practices had selected any particular AM fungus with specificity to potato plants. The AM fungal large-subunit (LSU) rRNA genes were subjected to nested PCR, cloning, sequencing, and phylogenetic analyses. One hundred eighty-three LSU rRNA sequences were analyzed, and eight monophyletic ribotypes, belonging to Glomus groups A and B, were identified. AM fungal communities differed between bulk soil and potato roots, as one AM fungal ribotype, corresponding to Glomus intraradices, was much more frequent in potato roots than in soils (accounting for more than 90% of sequences from potato samples and less than 10% of sequences from soil samples). A semiquantitative heminested PCR with specific primers was used to confirm and quantify the AM fungal abundance observed by cloning. Overall results concerning the biodiversity of AM fungal communities in roots and in bulk soils from the two studied areas suggested that potato roots were preferentially colonized by one AM fungal species, G. intraradices.     

Complexity of Semiarid Gypsophilous Shrub Communities Mediates the AMF Biodiversity at the Plant Species Level

The community composition of arbuscular mycorrhizal fungi (AMF) was analyzed in roots of Gypsophila struthium growing in gypsum soils under semiarid conditions. In order to investigate the effect of plant community degradation on the AMF biodiversity at the single species level, on the basis of the plant community complexity level, we selected four areas affected by degradation and shrub species spatial heterogeneity. The AM fungal community colonizing G. struthium was investigated from the morphological and molecular points of view. All plants were well colonized and showed a high level of infective AM propagules. Roots were analyzed by polymerase chain reaction, restriction fragment length polymorphism screening, and sequence analyses of the ribosomal DNA small subunit region. Four AM fungal types were identified and clustered into the AM fungal family: Glomeraceae, Glomus being the only taxon present. One fungal type was present in all the selected areas. Two fungal types are distinct from any previously published sequences and could be specific to gypsum soils. The chemical–physical properties of the soil were not correlated with the AMF diversity in roots. Our data show vegetation cover complexity-dependent differences in the AM fungal community composition.     

Arbuscular mycorrhizal fungi associated with common pteridophytes in Dujiangyan,southwest China

The colonization and diversity of arbuscular mycorrhizal (AM) fungi associated with common pteridophytes were investigated in Dujiangyan, southwest China. Of the 34 species of ferns from 16 families collected, 31 were colonized by AM fungi. The mean percentage root length colonized was 15%, ranging from 0 to 47%. Nineteen species formed Paris-type and 10 intermediate-type AM. In two ferns, only rare intercellular non-septate hyphae or vesicles were observed in the roots and AM type could not be determined. Of the 40 AM fungal taxa belonging to five genera isolated from rooting-zone soils, 32 belonged to Glomus, five to Acaulospora, one to Archaeospora, one to Entrophospora, and one to Gigaspora. Acaulospora and Glomus were the dominant genera and Glomus versiforme was the most common species. The average AM spore density was 213 per 100 g air-dried soil and the average species richness was 3.7 AM species per soil sample. There was no correlation between spore density and percentage root length colonized by AM fungi.     

Interactive effects of temperature and arbuscular mycorrhizal fungi on growth,P uptake and root respiration of<Emphasis Type="Italic"> Capsicum annuum</Emphasis> L.

Capsicum annuum (pepper) plants were inoculated with the arbuscular mycorrhizal (AM) fungi Glomus intraradices Smith and Schenck, an undescribed Glomus sp. (AZ 112) or a mixture of these isolates. Control plants were non-mycorrhizal. Plants were grown for 8 weeks at moderate (20.7–25.4°C) or high (32.1–38°C) temperatures. Colonization of pepper roots by G. intraradices or the Glomus isolate mixture was lower at high than at moderate temperatures, but colonization by Glomus AZ112 was somewhat increased at high temperatures. Pepper shoot and root dry weights and leaf P levels were affected by an interaction between temperature and AM fungal treatments. At moderate temperatures, shoot dry weights of plants colonized by the Glomus isolate mixture or non-AM plants were highest, while root dry weights were highest for non-AM plants. At high temperatures, plants colonized by Glomus AZ112 or the non-AM plants had the lowest shoot and root dry weights. AM plants had generally higher leaf P levels at moderate temperatures and lower P levels at high temperatures than non-AM plants. AM plants also had generally higher specific soil respiration than non-AM plants regardless of temperature treatment. At moderate temperatures, P uptake by all AM plants was enhanced relative to non-AM plants but there was no corresponding enhancement of growth, possibly because less carbon was invested in root growth or root respiratory costs increased. At high temperatures, pepper growth with the G. intraradices isolate and the Glomus isolate mixture was enhanced relative to non-AM controls, despite reduced levels of AM colonization and, therefore, apparently less fungal P transfer to the plant.     

Subcellular Nutrient Element Localization and Enrichment in Ecto- and Arbuscular Mycorrhizas of Field-Grown Beech and Ash Trees Indicate Functional Differences

Mycorrhizas are the chief organ for plant mineral nutrient acquisition. In temperate, mixed forests, ash roots (Fraxinus excelsior) are colonized by arbuscular mycorrhizal fungi (AM) and beech roots (Fagus sylvatica) by ectomycorrhizal fungi (EcM). Knowledge on the functions of different mycorrhizal species that coexist in the same environment is scarce. The concentrations of nutrient elements in plant and fungal cells can inform on nutrient accessibility and interspecific differences of mycorrhizal life forms. Here, we hypothesized that mycorrhizal fungal species exhibit interspecific differences in mineral nutrient concentrations and that the differences correlate with the mineral nutrient concentrations of their associated root cells. Abundant mycorrhizal fungal species of mature beech and ash trees in a long-term undisturbed forest ecosystem were the EcM Lactarius subdulcis, Clavulina cristata and Cenococcum geophilum and the AM Glomus sp. Mineral nutrient subcellular localization and quantities of the mycorrhizas were analysed after non-aqueous sample preparation by electron dispersive X-ray transmission electron microscopy. Cenococcum geophilum contained the highest sulphur, Clavulina cristata the highest calcium levels, and Glomus, in which cations and P were generally high, exhibited the highest potassium levels. Lactarius subdulcis-associated root cells contained the highest phosphorus levels. The root cell concentrations of K, Mg and P were unrelated to those of the associated fungal structures, whereas S and Ca showed significant correlations between fungal and plant concentrations of those elements. Our results support profound interspecific differences for mineral nutrient acquisition among mycorrhizas formed by different fungal taxa. The lack of correlation between some plant and fungal nutrient element concentrations may reflect different retention of mineral nutrients in the fungal part of the symbiosis. High mineral concentrations, especially of potassium, in Glomus sp. suggest that the well-known influence of tree species on chemical soil properties may be related to their mycorrhizal associates.     

Arbuscular mycorrhizal and dark septate endophytic fungi at 5,500 m on a glacier forefront in the Qinghai-Tibet Plateau, China

Arbuscular mycorrhizal (AM) and dark septate endophytic (DSE) fungi are rarely studied at extremely high elevations. Here, AM and DSE colonization in two dominant plant species (Melandrium apetalum and Poa litwinowiana) were microscopically observed on the forefront of Zhadang Glacier (5,500 m above sea level) in the Qinghai-Tibet Plateau, China. The AM fungal taxa were also identified by molecular methods. Both AM and DSE fungi synchronously colonized these two plant species, but AM dominated in M. apetalum and DSE dominated in P. litwinowiana. A total of five AM fungal spore morphotypes (Acaulospora capsicula, Diversispora sp., Glomus constrictum, G. eburneum and Glomus sp.) were found in the rhizosphere soils. Molecular identification revealed two AM fungal phylotypes: one Claroideoglomus phylotype from roots and one Diversispora phylotype from spores. These results extend the elevation at which both AM and DSE are known to occur.     

Morphological and Molecular Evidence of Arbuscular Mycorrhizal Fungal Associations in Costa Rican Epiphytic Bromeliads1

Arbuscular mycorrhizal fungi influence the growth, morphology, and fitness of a variety of plant species, but little is known of the arbuscular mycorrhizal (AM) fungal associations of plant species in forest canopies. Plant species' associations with AM fungi are most often elucidated by examining the roots for fungal structures; however, morphological data may provide a limited resolution on a plant's mycorrhizal status. We combined a traditional staining technique with a molecular marker (the 18S ribosomal gene) to determine whether or not a variety of epiphytic bromeliads form arbuscular mycorrhizal fungal associations. Using these methods we show that the epiphytic bromeliad Vriesea werkleana forms arbuscular mycorrhizal fungal associations with members of the genus Glomus. AM fungal sequences of this plant species formed three distinct clades nested within a larger Glomus clade; two of the clades did not group with any previously sequenced lineage of Glomus. Novel clades may represent novel species. Although Vriesea werkleana is associated with multiple AM fungal species, each individual plant is colonized by a single lineage. The combination of morphological and molecular methods provides a practical approach to the characterization of the mycorrhizal status of epiphytic bromeliads, and perhaps other tropical epiphytes.     

Distribution of dominant arbuscular mycorrhizal fungi among five plant species in undisturbed vegetation of a coastal grassland

Most plant species in mixed grassland vegetation are colonized by arbuscular mycorrhizal (AM) fungi. Previous studies have reported differences in host preferences among AM fungi, although the fungi are known to lack host specificity. In the present study, the distribution of phylogenetic groups of AM fungi belonging to a clade of Glomus species was studied in five plant species from a coastal grassland in Denmark. The occurrence of the fungi was determined by PCR analyses of fungal large subunit ribosomal DNA sequences amplified from root fragments using a specific primer set. The results showed that the dominant Glomus species were able to colonize all the studied plant species, supporting the view that the AM fungi represent a large underground interconnecting mycelial network.     

The Effect of Sulfur on the Composition of Arbuscular Mycorrhizal Fungal Communities During the Pod-Setting Stage of Different Soybean Cultivars

This study sought to investigate the effect of sulfur levels on changes in the fungal community composition of arbuscular mycorrhizae (AM) at the pod-setting stage and the relationship between the amount of applied sulfur and AM fungal diversity in different soybean cultivars. The objective of the research was to determine the optimal sulfur application level for different soybean cultivars and to improve soybean yield and quality from the perspective of AM fungal diversity. Three soybean cultivars, Heinong 44, Heinong 48, and Heinong 37, were selected as study materials. In addition to 0.033?g each of N, P₂O₅ and K₂O per kg of soil, 0, 0.02, 0.04, or 0.06?g of elemental sulfur was applied to each kg of soil for the four treatment groups, S1, S2, S3, and S4, respectively. The AM fungal community structure was analyzed in the soil and root of different soybean cultivars using the PCR-DGGE technology. The results indicated a significant effect of sulfur on the AM fungal community structure in the roots and rhizospheric soil of different soybean cultivars. The three soybean cultivars in group S2 exhibited the highest diversity in AM fungus. Significant changes in the dominant fungal species were observed in the DGGE fingerprints of each sample, and Glomus, Funneliformis, Rhizophagus, and Claroideoglomus fungi were the dominant species of AM fungus in the roots and soil of soybean. The application of an appropriate amount of sulfur improved the diversity of AM fungi in roots and rhizospheric soil of different soybean cultivars.     

Communities of arbuscular mycorrhizal fungi in Stipa krylovii (Poaceae) in the Mongolian steppe

We examined arbuscular mycorrhizal (AM) fungi colonizing the roots of Stipa krylovii, a grass species dominating the grasslands of the steppe zone in Hustai and Uvurkhangai in Mongolia. The AM fungal communities of the collected S. krylovii roots were examined by molecular analysis based on the partial sequences of a small subunit of ribosomal RNA gene as well as AM fungal colonization rates. Almost all AM fungi detected were in Glomus-group A, and were divided into 10 phylotypes. Among them, one phylotype forming a clade with G. intraradices and G. irregulare was the most dominant. Furthermore, it was also found that most of the phylotypes include AM fungi previously detected in high altitude regions in the Eurasian Continent. Significant correlations were found among soil total N, total plant biomass and AM fungal colonization ratio, which suggested that higher plant biomass may be required for the proliferation of AM fungi in the environment. Meanwhile, redundancy analysis on AM fungal distribution and environmental variables suggested that the effect of plant biomass and most soil chemical properties on the AM fungal communities were not significant.     

Colonization Characteristics and Diversity of Arbuscular Mycorrhizal Fungi in the Rhizosphere of <i>Iris lactea</i> in Songnen Saline-alkaline Grassland

To understand arbuscular mycorrhizal (AM) fungi resources and develop AM fungal species in ornamental plants with saline-alkaline tolerances, Iris lactea, which grows in the Songnen saline-alkaline grassland with a high ornamental value, was selected as the experimental material, and the colonization characteristics of its roots and the AM fungal diversity in its rhizosphere were explored. The results of the observations and calculations of mycorrhizae from ten different samples showed that AM fungi colonized the roots of I. lactea and formed Arum-type mycorrhizal structures. There was a significant correlation between soil spore density and pH value, while the colonization rate showed a fluctuating trend with increasing pH values. The observed colonization intensities were of Levels II (1%–10%) or III (11%–50%), and the vesicle abundances were of grades A₂ or A₃ among different sites. AM fungi produced a large number of mycelia and vesicles in the roots of I. lactea after colonization. Thirty-seven species belonging to 15 genera of AM fungi were isolated from the rhizosphere of I. lactea and identified by morphological identification. Funneliformis and Glomus were the dominant genera, accounting for 21.79% and 20.85% of the total number, respectively. F. mosseae and Rhizophagus intraradices were isolated in all samples with importance values of 58.62 and 51.19, respectively. These results are expected to provide a theoretical basis for the analysis of the salt tolerance mechanism of I. lactea and for the discovery, exploration and further screening of AM fungal resources with salinity tolerances in saline-alkaline soils.     

Arbuscular mycorrhizal fungi associated with the Meliaceae on Hainan island, China

Species richness, spore density, frequency of occurrence, and relative abundance of AM fungi were determined in rhizosphere soil samples from nine tropical rainforest sites on Hainan island, south China, and the arbuscular mycorrhizal (AM) status of members of the Meliaceae was examined. All 28 plant taxa investigated (25 species including two varieties of 1 species and three varieties of another) were colonized by AM fungi. The mean proportion of root length colonized was 56% (range 10–95%). Vesicles were observed in 27 and hyphal coils in 26 of the 28 plant taxa. Mycorrhizas were of the Paris-type or intermediate-type, with no Arum-type mycorrhizas observed. Species richness of AM fungi varied from 3 to 15 and spore density from 46 to 1,499 per 100 g rhizosphere soil. Of 33 AM fungal taxa in five genera isolated and identified, 18 belonged to Glomus, 9 to Acaulospora, 1 to Entrophospora, 2 to Gigaspora, and 3 to Scutellospora. Acaulospora and Glomus were the dominant genera identified. Glomus claroideum was the taxon most commonly isolated, with a frequency of occurrence of 56.5% and relative abundance of 10.4%. A positive correlation was found between percentage of root length colonization and species richness. However, there was no correlation between spore density and percentage of root length colonized by AM fungi.     

Arbuscular mycorrhizal and septate endophyte fungal associations in lycophytes and ferns of south India

We studied extent and type of arbuscular mycorrhizal (AM) and septate endophytic (SE) fungal associations in five lycophytes and 50 ferns collected from Eastern and Western Ghats regions. Of the 54 species and one variety (belonging to 31 genera) examined; 54 taxa had AM association and AM fungal structures were absent in Marsilea quadrifolia. This is the first report of AM and SE fungal status for 26 species each. Of the 55 taxa examined, AM morphology has been evaluated for the first time in 51 species. The hydrophytic fern Salvinia molesta was mycorrhizal and non-mycorrhizal at different sites. All the epiphytic and saxicolous species examined were mycorrhizal. The percentage of AM colonization ranged from 22.23 (Christella parasitica) to 82.20 (Adiantum lunulatum) in ferns and 53.46 (Selaginella bryopteris) to 84.34 (Selaginella sp.) in lycophytes. Epiphytic life-forms had the maximum average AM colonization levels, whereas aquatic life-forms had the minimum colonization levels. The percentage root length colonized by septate fungi ranged between 0.59 in Ophioglossum reticulatum and 16.36 in Pteris pellucida. The root length with AM and SE fungal structures as well as their total colonization significantly varied among the taxa examined. Most of the lycophytes and ferns had intermediate-type of AM morphology with a few exhibiting Paris-type. AM fungal spore numbers ranged from 1.0 (Angiopteris evecta, Pteridium aquilinum) to (Nephrolepis exaltata) 9.3 spores per 25 g soil and varied significantly among taxa. AM fungal spore morphotypes belonging to Claroideoglomus, Funneliformis, Glomus and Rhizophagus were recorded.     

The co-occurrence of ectomycorrhizal,arbuscular mycorrhizal,and dark septate fungi in seedlings of four members of the Pinaceae

Although roots of species in the Pinaceae are usually colonized by ectomycorrhizal (EM) fungi, there are increasing reports of the presence of arbuscular mycorrhizal (AM) and dark septate endophytic (DSE) fungi in these species. The objective of this study was to determine the colonization patterns in seedlings of three Pinus (pine) species (Pinus banksiana, Pinus strobus, Pinus contorta) and Picea glauca x Picea engelmannii (hybrid spruce) grown in soil collected from a disturbed forest site. Seedlings of all three pine species and hybrid spruce became colonized by EM, AM, and DSE fungi. The dominant EM morphotype belonged to the E-strain category; limited colonization by a Tuber sp. was found on roots of Pinus strobus and an unknown morphotype (cf. Suillus–Rhizopogon group) with thick, cottony white mycelium was present on short roots of all species. The three fungal categories tended to occupy different niches in a single root system. No correlation was found between the percent root colonized by EM and percent colonization by either AM or DSE, although there was a positive correlation between percent root length colonized by AM and DSE. Hyphae and vesicles were the only AM intracellular structures found in roots of all species; arbuscules were not observed in any roots.     

Effect of environmental gradient in coastal vegetation on communities of arbuscular mycorrhizal fungi associated with Ixeris repens (Asteraceae)

The community structure of arbuscular mycorrhizal (AM) fungi associated with Ixeris repens was studied in coastal vegetation near the Tottori sand dunes in Japan. I. repens produces roots from a subterranean stem growing near the soil surface which provides an opportunity to examine the effects of an environmental gradient related to distance from the sea on AM fungal communities at a regular soil depth. Based on partial sequences of the nuclear large subunit ribosomal RNA gene, AM fungi in root samples were divided into 17 phylotypes. Among these, five AM fungal phylotypes in Glomus and Diversispora were dominant near the seaward forefront of the vegetation. Redundancy analysis of the AM fungal community showed significant relationships between the distribution of phylotypes and environmental variables such as distance from the sea, water-soluble sodium in soil, and some coexisting plant species. These results suggest that environmental gradients in the coastal vegetation can be determinants of the AM fungal community.     

Communities of arbuscular mycorrhizal fungi in grassland: Seasonal variability and effects of environment and host plants

The seasonal dynamics of a community of endomycorrhizal fungal morphotypes in the roots of three grassland species (Achillea millefolium, Poa angustifolia, Plantago lanceolata) was evaluated, together with the effects of experimental treatment (mowing and phosphorus application) and the host plant properties. Strong seasonal variability was found in the fungal community, where clear seasonal patterns can be distinguished for several fungal morphotypes. The sampling date explained 20 to 30% of the total compositional variability for all three host species. ThePlantago roots host the highest number of arbuscular mycorrhizal (AM) fungal populations. There are two co-dominant fungal morphotypes inAchillea roots (assigned to the generaScutellospora andGlomus) and only one strongly dominant morphotype (assigned toGlomus), in thePoa roots. All three host species have a comparable pattern of richness of AM morphotypes with a single peak in the summer, possibly aligned with the flowering time of the host.     

Characterization of Arbuscular Mycorrhizal Fungus Communities of Aquilaria crassna and Tectona grandis Roots and Soils in Thailand Plantations

Aquilaria crassna Pierre ex Lec. and Tectona grandis Linn.f. are sources of resin-suffused agarwood and teak timber, respectively. This study investigated arbuscular mycorrhizal (AM) fungus community structure in roots and rhizosphere soils of A. crassna and T. grandis from plantations in Thailand to understand whether AM fungal communities present in roots and rhizosphere soils vary with host plant species and study sites. Terminal restriction fragment length polymorphism complemented with clone libraries revealed that AM fungal community composition in A. crassna and T. grandis were similar. A total of 38 distinct terminal restriction fragments (TRFs) were found, 31 of which were shared between A. crassna and T. grandis. AM fungal communities in T. grandis samples from different sites were similar, as were those in A. crassna. The estimated average minimum numbers of AM fungal taxa per sample in roots and soils of T. grandis were at least 1.89 vs. 2.55, respectively, and those of A. crassna were 2.85 vs. 2.33 respectively. The TRFs were attributed to Claroideoglomeraceae, Diversisporaceae, Gigasporaceae and Glomeraceae. The Glomeraceae were found to be common in all study sites. Specific AM taxa in roots and soils of T. grandis and A. crassna were not affected by host plant species and sample source (root vs. soil) but affected by collecting site. Future inoculum production and utilization efforts can be directed toward the identified symbiotic associates of these valuable tree species to enhance reforestation efforts.