不同施肥处理对丛枝菌根真菌生态分布的影响

研究了在东北海伦实验站长期定位培肥实验地不同施肥处理下丛枝菌根（Arbuscular Mycorrhizal,AM）真菌生长发育状况（包括侵染率、菌丝量和孢子数）,同时还分析了不同施肥处理下AM真菌群落生态分布和特征.结果表明施肥处理,尤其是磷肥（NP2K）处理显著降低AM真菌侵染玉米根系,而根外菌丝长度和孢子数并无显著变化,这和施肥处理下AM真菌的种群结构发生变化有关.随着土壤肥力的增高,土壤中AM真菌种的丰度和密度都有增加的趋势,而当肥力增高到一定程度后（磷肥和钾肥继续增加到NP2K和NPK2处理后）,土壤中AM真菌种的丰度和密度都有下降的趋势;从AM真菌属在不同肥力处理下出现的频度来看,Glomus属在7个处理中出现的频度最高,在每一个肥力处理中都有分布,Acaullospora属次之,Entrohospora属则只是出现在NK处理下;而Glomus属中出现频度最高的种是Glomus mosseae,其次是Glomus caledonium;再次是Glomus diaphanium,这说明施肥处理会影响到AM真菌种属的分布,进而影响到AM真菌的群落结构和生态分布.     

Host preferences of arbuscular mycorrhizal fungi colonizing annual herbaceous plant species in semiarid mediterranean prairies

In this study, we have analyzed and compared the diversities of the arbuscular mycorrhizal fungi (AMF) colonizing the roots of five annual herbaceous species (Hieracium vulgare, Stipa capensis, Anagallis arvensis, Carduus tenuiflorus, and Avena barbata) and a perennial herbaceous species (Brachypodium retusum). Our goal was to determine the differences in the communities of the AMF among these six plant species belonging to different families, using B. retusum as a reference. The AMF small-subunit rRNA genes (SSU) were subjected to nested PCR, cloning, sequencing, and phylogenetic analysis. Thirty-six AMF phylotypes, belonging to Glomus group A, Glomus group B, Diversispora, Paraglomus, and Ambispora, were identified. Five sequence groups identified in this study clustered to known glomalean species or isolates: group Glomus G27 to Glomus intraradices, group Glomus G19 to Glomus iranicum, group Glomus G10 to Glomus mosseae, group Glomus G1 to Glomus lamellosum/etunicatum/luteum, and group Ambispora 1 to Ambispora fennica. The six plant species studied hosted different AMF communities. A certain trend of AMF specificity was observed when grouping plant species by taxonomic families, highlighting the importance of protecting and even promoting the native annual vegetation in order to maintain the biodiversity and productivity of these extreme ecosystems.     

Are there benefits of simultaneous root colonization by different arbuscular mycorrhizal fungi?

Arbuscular mycorrhizal fungal (AMF) communities were established in pots using fungal isolates from a single field in Switzerland. It was tested whether multispecies mixtures provided more phosphorus and supported greater plant growth than single AMF species. Two host plants, medic (Medicago truncatula) and leek (Allium porrum), were inoculated with three AMF species (Glomus mosseae, G. claroideum and G. intraradices), either separately or in mixtures. The composition of the AMF communities in the roots was assessed using real-time PCR to determine the copy number of large ribosomal subunit genes. Fungal communities in the roots were usually dominated by one AMF species (G. mosseae). The composition of the communities depended on both plant identity and the time of harvest. Leek colonized by a mixture of G. claroideum and G. intraradices acquired more P than with either of the two AMF separately. Direct evidence is provided for functional complementarity among species within the AMF community colonizing a single root system. Competition among the species poses a major challenge in interpreting experiments with mixed inoculations, but this is greatly facilitated by use of real-time PCR.     

Role of Extrinsic Arbuscular Mycorrhizal Fungi in Heavy Metal-Contaminated Wetlands with Various Soil Moisture Levels

This study presents an efficient heavy metal (HM) control method in HM-contaminated wetlands with varied soil moisture levels through the introduction of extrinsic arbuscular mycorrhizal fungi (AMF) into natural wetland soil containing indigenous AMF species. A pot culture experiment was designed to determine the effect of two soil water contents (5–8% and 25–30%), five extrinsic AMF inoculants (Glomus mosseae, G. clarum, G. claroideum, G. etunicatum, and G. intraradices), and HM contamination on root colonization, plant growth, and element uptake of common reed (Phragmites australis (Cav.) Trin. ex Steudel) plantlets in wetland soils. This study showed the prevalence of mycorrhizae in the roots of all P. australis plantlets, regardless of extrinsic AMF inoculations, varied soil moisture or HM levels. It seems that different extrinsic AMF inoculations effectively lowered HM concentrations in the aboveground tissues of P. australis at two soil moisture levels. However, metal species, metal concentrations, and soil moisture should also be very important factors influencing the elemental uptake performance of plants in wetland ecosystems. Besides, the soil moisture level significantly influenced plant growth (including height, and shoot and root dry weight (DW)), and extrinsic AMF inoculations differently affected shoot DW.     

西藏高原天然长芒草地丛枝菌根真菌接种效应

采用草地均匀打孔方法,就草地土壤未消毒条件下接种丛枝菌根（AM）真菌对长芒草(Stipa bungeana)的侵染效应以及对植物生长、吸磷效率、土壤微生物区系等的影响进行研究.结果表明,1)接种处理、不接种处理的菌根效应存在着明显的差异,多数接种处理根围土壤AM真菌孢子密度、菌根侵染率和侵染强度显著提高,但对丛枝丰度的影响相对较低.2)接种后AM真菌孢子密度对菌根侵染率具有极显著影响(r=0.7679**);随菌根侵染率的增加,植株总干物重和吸磷总量均呈极显著提高,r值分别为0.7556**、0.8018**.3)与植株地上部相比,接种AM真菌对提高根系干物重、根系吸磷量和含磷量的促进作用相对较大.4)多数接种处理根际土壤酸性磷酸酶、碱性磷酸酶活性均呈一定程度的提高,根际土壤细菌数量显著增加,真菌、放线菌的数量变化则不甚明显.5)各接种处理对寄主植物的综合侵染效应在总体上呈Glomus mosseae+G. intraradices+Scutellospora calospora＞G. mosseae+G. aggregatum＞Glomus sp.＞G. mosseae＞G. mosseae+ G. etunicatum+G. intraradices+S. erythropa＞G. geosporum的趋势.     

Cooccurring Gentiana verna and Gentiana acaulis and their neighboring plants in two Swiss upper montane meadows harbor distinct arbuscular mycorrhizal fungal communities

The community composition of arbuscular mycorrhizal fungi (AMF) was analyzed in roots of Gentiana verna, Gentiana acaulis, and accompanying plant species from two species-rich Swiss alpine meadows located in the same area. The aim of the study was to elucidate the impact of host preference or host specificity on the AMF community in the roots. The roots were analyzed by nested PCR, restriction fragment length polymorphism screening, and sequencing of ribosomal DNA small-subunit and internal transcribed spacer regions. The AMF sequences were analyzed phylogenetically and used to define monophyletic sequence types. The AMF community composition was strongly influenced by the host plant species, but compositions did not significantly differ between the two sites. Detailed analyses of the two cooccurring gentian species G. verna and G. acaulis, as well as of neighboring Trifolium spp., revealed that their AMF communities differed significantly. All three host plant taxa harbored AMF communities comprising multiple phylotypes from different fungal lineages. A frequent fungal phylotype from Glomus group B was almost exclusively found in Trifolium spp., suggesting some degree of host preference for this fungus in this habitat. In conclusion, the results indicate that within a relatively small area with similar soil and climatic conditions, the host plant species can have a major influence on the AMF communities within the roots. No evidence was found for a narrowing of the mycosymbiont spectrum in the two green gentians, in contrast to previous findings with their achlorophyllous relatives.     

A method for assessing arbuscular mycorrhizal fungi group distribution in tree roots by intergenic transcribed sequence variation

We identified five taxonomic groups of arbuscular mycorrhizal fungi (AMF) inside roots of young trees of six species of legumes and six species of non-legumes from a field site in southern Costa Rica using an AMF group-specific PCR assay of the intergenic transcribed sequence and 18S rRNA gene fragment. Assay specificity was verified by cloning and sequencing representatives from four of the five AMF groups. We found no difference in overall AMF diversity levels between legumes and non-legumes or between plant species. Some groups of AMF may associate more frequently with legumes than others, as Glomus Group A (Glomus mosseae/intradices group) representatives were detected more frequently in legumes than non-legumes relative to Glomus Group B (Glomus etunicatum/claroideum) representatives.     

山东省不同植被区内野生植物根围AM菌的生态分布

ＡＭ菌是土壤习居菌 ,生态适应性强 ,可发生在各种生态环境。寄主范围也十分广泛 ,除少量植物如莎草科、苋科、灯心草科、藜科、石竹科等 2 0余科植物不能或不易形成ＡＭ外 ,大多数植物包括苔藓、蕨类、裸子植物、被子植物都能被菌根菌侵染。当前人们十分重视对野生植物上ＡＭ菌的调查[3 ,4 ,1 0 ,1 1 ,1 4 ]。研究发现 ,野生植物上可能有比栽培作物更多的ＡＭ菌种类[1 ]。我国野生植物资源丰富 ,开发和利用野生寄主植物上的ＡＭ菌潜力巨大。由于ＡＭ菌对寄主植物的选择性及对环境条件的适应性不同 ,或进化过程中的历史原因 ,造成了自然生态…     

Diverse communities of arbuscular mycorrhizal fungi inhabit sites with very high altitude in Tibet Plateau

Diversity of arbuscular mycorrhizal fungi (AMF) is well studied in many ecosystems, but little is known about AMF in cold-dominated regions with very high altitude. Here, we examined AMF communities associated with two plant species in the Tibet Plateau. Roots and rhizosphere soils of Dracocephalum heterophyllum (pioneer species) and Astragalus polycladus (late-successional species) were sampled at five sites with altitude from 4500 to 4800 m a.s.l. A total of 21 AMF phylotypes were identified from roots and spores following cloning and sequencing of 18S rRNA gene, including eight new phylotypes and one new family-like clade. More AMF phylotypes colonized root samples of D. heterophyllum (5.4±0.49) than of A. polycladus (1.93±0.25). Vegetation coverage was the most important factor influencing AMF community composition in roots. Globally infrequent phylotype Glo-B2 in Glomus group B was the most dominant in roots, followed by globally frequent phylotype Glo-A2 related to Glomus fasciculatum/intraradices group. Our findings suggest that a diverse AMF flora is present in the Tibet Plateau, comprising both potentially habitat-selective and generalist fungi.     

Genetic structure of arbuscular mycorrhizal populations in fallow and cultivated soils

The impact of fallowing on the genetic structure of arbuscular mycorrhizal fungi (AMF) was studied by hierarchical sampling of spores from four plots in a fallow and a cultivated field. A nested multiplex PCR approach was used to assign the spores to genotypes. Variable introns of the two protein-coding genes GmFOX2 and GmTOR2 were used as co-dominant genetic markers together with the large subunit (LSU) rDNA. The gene diversity and genetic structure of Glomus mosseae, Glomus geosporum and Glomus caledonium were compared within and between the fields. Spores of G. caledonium and G. geosporum were more abundant in the cultivated field, whereas G. mosseae was more frequent in the fallow field. The number of genotypes was not different between the two fields. Analysis of gene diversity of G. caledonium in the fallow field indicated that a larger part of the heterogeneity could be attributed to variation between plots rather than subplots, suggesting that the lack of soil cultivation resulted in more heterogeneous population genetic structures. Analyses of haplotype networks of the fungi suggested a subdivision of G. mosseae haplotypes between the two fields, whereas no such division was seen in G. geosporum and G. caledonium. The results show that agricultural practices differently affect both the abundance and the population structure of different AMF species.     

The cultivation bias: different communities of arbuscular mycorrhizal fungi detected in roots from the field,from bait plants transplanted to the field,and from a greenhouse trap experiment

The community composition of arbuscular mycorrhizal fungi (AMF) was investigated in roots of four different plant species (Inula salicina, Medicago sativa, Origanum vulgare, and Bromus erectus) sampled in (1) a plant species-rich calcareous grassland, (2) a bait plant bioassay conducted directly in that grassland, and (3) a greenhouse trap experiment using soil and a transplanted whole plant from that grassland as inoculum. Roots were analyzed by AMF-specific nested polymerase chain reaction, restriction fragment length polymorphism screening, and sequence analyses of rDNA small subunit and internal transcribed spacer regions. The AMF sequences were analyzed phylogenetically and used to define monophyletic phylotypes. Overall, 16 phylotypes from several lineages of AMF were detected. The community composition was strongly influenced by the experimental approach, with additional influence of cultivation duration, substrate, and host plant species in some experiments. Some fungal phylotypes, e.g., GLOM-A3 (Glomus mosseae) and several members of Glomus group B, appeared predominantly in the greenhouse experiment or in bait plants. Thus, these phylotypes can be considered r strategists, rapidly colonizing uncolonized ruderal habitats in early successional stages of the fungal community. In the greenhouse experiment, for instance, G. mosseae was abundant after 3 months, but could not be detected anymore after 10 months. In contrast, other phylotypes as GLOM-A17 (G. badium) and GLOM-A16 were detected almost exclusively in roots sampled from plants naturally growing in the grassland or from bait plants exposed in the field, indicating that they preferentially occur in late successional stages of fungal communities and thus represent the K strategy. The only phylotype found with high frequency in all three experimental approaches was GLOM A-1 (G. intraradices), which is known to be a generalist. These results indicate that, in greenhouse trap experiments, it is difficult to establish a root-colonizing AMF community reflecting the diversity of these fungi in the field roots because fungal succession in such artificial systems may bias the results. However, the field bait plant approach might be a convenient way to study the influence of different environmental factors on AMF community composition directly under the field conditions. For a better understanding of the dynamics of AMF communities, it will be necessary to classify AMF phylotypes and species according to their life history strategies.     

Copper sorption and accumulation by the extraradical mycelium of different Glomus spp. (arbuscular mycorrhizal fungi) isolated from the same polluted soil

The form and localisation of Cu accumulation in the extraradical mycelium (ERM) of three arbuscular mycorrhizal fungi (AMF), isolated from the same polluted soil contaminated with the Cu and Arsenate, was studied. There were differences in the capacity of the ERM of the three AMF to sorb and accumulate Cu. Glomus caledonium BEG133 had a significantly lower Cu-sorption capacity than Glomus mosseae BEG132 and Glomus claroideum BEG134 isolated from the polluted soil as well as an isolate of G. mosseae BEG25 from a non-polluted soil. This was directly related to the cation exchange capacity (CEC) of the ERM of these fungi. Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) linked to an energy dispersive X-ray spectrometer (EDAX) gave more detailed information, showing that the ERM of AMF from the polluted soil was able to accumulate Cu in the mucilaginous outer hyphal wall zone, cell wall and inside the hyphal cytoplasm. The EDAX spectra showed that the accumulated Cu was mainly associated with Fe in the mucilaginous outer hyphal wall zone and in the cell wall. Cu was associated with traces of arsenate inside the cytoplasm of the ERM of Glomus mosseae BEG132 but this was not visible inside the ERM of Glomus caledonium BEG133 or Glomus claroideum BEG134. This work suggests that the ERM of AMF is able to sorb and accumulate Cu, but different tolerance mechanisms exist between the three AMF isolated from the same polluted soil providing further evidence for functional diversity within populations of AMF in soils.     

西双版纳四种壳斗科植物丛枝菌根状况的初步研究

研究了西双版纳热带次生林中杯丝锥(Castanopsis calathiformis)、红锥(C.hys-trix)、印度锥(C.indica)和截果柯(Lithocarpus truncatus)4种壳斗科植物的丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)的侵染状况,并从这些植物的根际土壤中分离鉴定了隶属于球囊霉属(Glomus)、巨孢囊霉属(Gigaspora)、盾巨孢囊霉属(Scutellospora)和无梗囊霉属(Acaulospora)的10种丛枝菌根真菌。这4种壳斗科植物根际AMF的孢子密度为14~22个.100g-1土壤,种的丰富度在4~7,平均频度为60.00%,相对多度为4.41%~22.06%,丛枝菌根真菌的定居水平达46.26%~51.40%。     

Diversity and infectivity of arbuscular mycorrhizal fungi in agricultural soils of the Sichuan Province of mainland China

Knowledge about the presence and diversity of arbuscular mycorrhizal fungi (AMF) in a specific area is an essential first step for utilizing these fungi in any application. The community composition of AMF in intensively managed agricultural soil in the Sichuan Province of southwest China currently is unknown. In one set of samples, AMF were trapped in pot cultures from 40 fields growing legumes in the Panxi region, southeast Sichuan. In a second set of samples, the MPN method with four-fold dilutions and maize as host was used to estimate infective propagules in soil from another 50 agricultural sites throughout the province. Soil types were heterogeneous and were classified as purple, yellow, paddy and red. Crops at each site were either maize, wheat or sweet orange. From this set of soil, AMF spores were also extracted and identified. Including all ninety soils, thirty glomeromycotan species in Glomus (20 species), Acaulospora (four species), Scutellospora (three species), Ambispora (one species), Archaeospora (one species) and Paraglomus (one species) were identified. Yellow, red and purple soils yielded similar numbers of AMF species, while AMF species diversity was clearly lower in paddy soil. In trap culture soils, the most frequent species were Glomus aggregatum or Glomus intraradices, Glomus claroideum and Glomus etunicatum. The species Acaulospora capsicula, Acaulospora delicata, G. aggregatum (or intraradices), G. claroideum, Glomus epigaeum, G. etunicatum, Glomus luteum, Glomus monosporum, Glomus mosseae and Glomus proliferum were successfully cultured as single-species pot cultures in Plantago lanceolata. The three most frequent species in field soils were G. mosseae, Glomus caledonium and Glomus constrictum. MPN values varied between 17 and 3334 propagules 100 g soil⁻¹ among the fifty field sites sampled. Regression analysis, including host&soil, log(P) and pH as explanatory variables explained 59% of the variation in log(MPN). The highest MPN estimates were found in purple soil cropped with maize and citrus, 324 and 278 propagules 100 g soil⁻¹, respectively. The lowest MPN value, 54 propagules 100 g soil⁻¹, was measured in wheat in purple and yellow soil. Despite intensive agricultural management that can include often repeated tillage, our examination of 90 agricultural sites revealed that soils of the Sichuan region have moderate to high numbers of infective AMF propagules as well as a high AMF species diversity. This opens possibilities for further studies and utilization of AMF in agriculture and horticulture in the Sichuan province, People’s Republic of China.     

Biodiversity of arbuscular mycorrhizal fungi in roots and soils of two salt marshes

The occurrence of arbuscular mycorrhizal fungi (AMF) was assessed by both morphological and molecular criteria in two salt marshes: (i) a NaCl site of the island Terschelling, Atlantic Coast, the Netherlands and (ii) a K₂CO₃ marsh at Schreyahn, Northern Germany. The overall biodiversity of AMF, based on sequence analysis, was comparably low in roots at both sites. However, the morphological spore analyses from soil samples of both sites exhibited a higher AMF biodiversity. Glomus geosporum was the only fungus of the Glomerales that was detected both as spores in soil samples and in roots of the AMF-colonized salt plants Aster tripolium and Puccinellia sp. at both saline sites and on all sampling dates (one exception). In roots, sequences of Glomus intraradices prevailed, but this fungus could not be identified unambiguously from DNA of soil spores. Likewise, Glomus sp. uncultured, only deposited as sequence in the database, was widely detected by DNA sequencing in root samples. All attempts to obtain the corresponding sequences from spores isolated from soil samples failed consistently. A small sized Archaeospora sp. was detected, either/or by morphological and molecular analyses, in roots or soil spores, in dead AMF spores or orobatid mites. The study noted inconsistencies between morphological characterization and identification by DNA sequencing of the 5.8S rDNA-ITS2 region or part of the 18S rDNA gene. The distribution of AMF unlikely followed the salt gradient at both sites, in contrast to the zone formation of plant species. Zygotes of the alga Vaucheria erythrospora (Xanthophyceae) were retrieved and should not be misidentified with AMF spores.     

Molecular analysis of arbuscular mycorrhizal fungi colonising a semi-natural grassland along a fertilisation gradient

The community of arbuscular mycorrhizal fungi (AMF) colonizing the roots of Festuca pratensis and Achillea millefolium was characterized in a Swedish pasture at different times, along a gradient of fertilization. The small subunit ribosomal RNA gene was subjected to PCR and denaturing gradient gel electrophoresis (DGGE), sequencing and phylogenetic analysis. The sequences found in this study clustered in 10 discrete sequence groups, seven belonging to Glomus, two to Scutellospora and one to Diversispora. A negative correlation was observed between soil mineral nitrogen and the number of AMF sequence groups in the roots. The frequency of occurrence of AMF in roots decreased dramatically between June and September. No plant-host specificity could be detected.     

Impact of arbuscular mycorrhizal fungal inoculants on subsequent arbuscular mycorrhizal fungi colonization in pot-cultured field pea (Pisum sativum L.)

The use of commercial inoculants containing non-resident arbuscular mycorrhizal fungi (AMF) is an emerging technology in field crop production in Canada. The objective of this study was to assess the impact of AMF inoculants containing either a single species (Glomus irregulare) or mixed species (G. irregulare, Glomus mosseae, and Glomus clarum) on AMF root colonization and consequent plant growth parameters of field pea grown using pot cultures. Field pea was grown in both sterilized and non-sterile (i.e., natural) field-collected soil containing resident AMF and received three inoculation treatments: uninoculated control, G. irregulare only, and a mixture of AMF species of G. irregulare, G. mosseae, and G. clarum. After 42 days, the AMF community assembled in field pea roots was assessed by cloning and sequencing analysis on the LSU-ITS-SSU rDNA gene, together with a microscopic assessment of colonization, biomass production, nutrient uptake, and N₂ fixation. The identity of AMF inoculants had a significant effect on field pea performance. The mixed species AMF inoculant performed better than the single species G. irregulare alone by promoting mycorrhizal colonization, field pea biomass, N and P uptake, and N₂ fixation and did not result in a significant compositional change of the AMF community that subsequently assembled in field pea roots. In contrast, the single species G. irregulare inoculant did not significantly enhance field pea biomass, N and P uptake, and N₂ fixation, although a significant compositional change of the subsequent AMF community was observed. No significant interactions affecting these measurements were detected between the resident AMF and the introduced AMF inoculants. The observation that the mixed species AMF inoculant promoted plant growth parameters without necessarily affecting the subsequent AMF community may have important implications regarding the use of non-resident AMF inoculants in agricultural production.     

云南西双版纳野生与栽培绞股蓝根内丛枝菌根真菌的分子多样性

采用巢式-PCR、DNA克隆测序技术,对西双版纳地区野生与栽培绞股蓝根内丛枝菌根真菌(AMF)进行群落结构多样性研究.试验共获得551个含有丛枝菌根真菌18S rDNA 片段的克隆子,经限制性片段长度多态性分析,得到100个RFLP类型,将其划分为20个序列类型,分属于7个科.将20个序列类型的相关序列与GeneBank数据库进行比对,有5个可以鉴定到种,分别为Glomus viscosum、Claroideoglomus etunicatum、Racocetra tropicana、Acaulospora spinosa、Acaulospora mellea.与 MaarjAM数据库中序列进行比对,12个可鉴定为虚拟分类分子种,其中7个未在孢子形态学鉴定方法中获得.西双版纳地区野生与栽培绞股蓝根内丛枝菌根真菌群落组成差异极显著.野生绞股蓝根内Glo₂、Amb₁、Para₁为优势类群,而栽培绞股蓝根内Glo₃、Glo₈、Glo₁₀、Div₁为优势类群.Claroideoglomeraceae和Ambisporaceae仅在野生样本中出现,而Diversisporaceae仅在栽培样品中出现.     

Communities of arbuscular mycorrhizal fungi in arable soils are not necessarily low in diversity

Communities of arbuscular mycorrhizal fungi (AMF) in five agricultural field sites of different management intensities were studied. Variable regions of the ribosomal RNA genes were used to detect and identify AMF directly within colonized roots. Roots from a continuous maize monoculture showed low AMF diversity, in agreement with previous reports on molecular diversity of AMF in agricultural soils. In contrast, a substantially higher diversity of AMF was found throughout the long term 'DOK' field experiment, where organic and conventional agricultural practices have been compared side by side since 1978. In this experiment, a 7-year crop rotation is performed under lower levels of inorganic fertilizer input and chemical pest control. These results are in good agreement with analyses of the spore community previously conducted in these field sites. In a third site, an organically managed leek field with soil of very high phosphate content reflecting the highly intensive conventional field history and intensive tillage, we detected a low-diversity community comparable to the maize monoculture. In addition to fungi from Glomus group A, which have previously been reported to dominate arable soils, we regularly found members of the genera Scutellospora, Paraglomus and Acaulospora. The genus Acaulospora was shown to occur more frequently early in the growing season, suggesting that the life history strategy of AMF may influence the active community at a given time. These data show that the diversity of AMF is not always low in arable soils. Furthermore, low-input agriculture involving crop rotation may provide better conditions to preserve AMF diversity, by preventing the selection for the few AMF taxa tolerating high nutrient levels.