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

SummaryThe mycorrhizal symbiosis formed between plant roots and the arbuscular mycorrhizal (AM) fungi or Glomales is of great interest to ecologists because of its potential influence on ecosystem processes, its role in determining plant diversity in natural communities and the ability of the fungi to induce a wide variety of growth responses in coexisting plant species. Little attention, however, has been paid to the ecological role of diversity of AM fungi. Difficulties in identification, the inability to grow the fungi in pure culture, problems of taxonomic classification, and a lack of basic information on the life histories of AM fungi hinder studies of the ecological significance of diversity of AM fungi. Nucleic acid based techniques have the potential to fill this gap in our knowledge by offering better means of identification and the opportunity to study links between the genetic diversity of AM fungi and functional and morphological diversity. The application of genus‐specific molecular markers has shown that different genera of AM fungi coexist in plant roots and that this is a common occurrence. Molecular techniques have also shown that natural AM fungal populations exhibit unexpectedly high genetic diversity, despite the assumption that diversity in these seemingly asexual fungi should be low. The high diversity occurs in multicopy ribosomal genes and their internal transcribed spacers, which are normally well conserved and homogeneous within an individual organism. The results show that sequence heterogeneity of the ribosomal genes can occur even in single spores of AM fungi, and we discuss how genetic diversity may be promoted and maintained. Contrasting results, indicating that genetic diversity among replicate spores from pot‐cultured material is low (even though they contain within spore sequence heterogeneity), suggest that there are mechanisms which promote high genetic diversity of AM fungi in natural ecosystems.We propose that AM fungi could be heterokaryotic as a result of the exchange of nuclei following hyphal fusion with other individuals but that other mechanisms, such as gene turnover and molecular drive, might also explain the generation of high genetic diversity without any exchange of genetic material among individuals. The high diversity in ribosomal gene sequences in AM fungi might cause problems in their use as molecular markers in field studies. A better understanding of the levels of genetic diversity of ribosomal genes within spores, among spores of the same morphology, and among spores of differing morphology is essential to the development of sound molecular markers for field studies and to the development of a phylogenetic classification.We conclude that an understanding of the mechanisms which promote and maintain genetic diversity in the AM fungi is crucial, not only to further advances in ecological and evolutionary studies but also to studies of the molecular basis of the regulation of the symbiosis. Moreover, we predict that while observational investigations on AM fungal ecology and diversity using molecular techniques are of high value they will not give an understanding of the role of AM fungi in natural ecosystems and that further studies should also aim to fill the gaps in current knowledge of links between genetic diversity and distribution of AM fungi in natural ecosystems, and their functional diversity.

调查了福建省厦门市7种常见药用植物根围丛枝菌根真菌分布情况、侵染率及其多样性。结果表明:7种药用植物均能与AM真菌形成良好的共生关系,且不同药用植物形成菌根的能力差异明显,盐肤木根围的孢子密度最高,29.0 个/g土,喜树的侵染率最高,100%。含笑根围的孢子密度最低,4.7 个/g土,鱼腥草的总侵染率最低,4.5%。共分离鉴定AM真菌4属63种,其中球囊霉属(<em>Glomus</em>)39种、无梗囊霉属(<em>Acaulospora</em>)18种、巨孢囊霉属(<em>Gigaspora</em>)4种、盾巨孢囊霉属(<em>Scutellospora</em>)2种,其中<em>Glomus</em>、<em>Acaulospora</em>为优势属,黑球囊霉<em>G. melanosporum</em>为优势种。盐肤木根围AM真菌种类最丰富,Shannon-Weiner指数<em>H</em>达到1.29。侵染率与各土壤因子均无显著相关;孢子密度与pH值极显著负相关;种的丰度与pH值显著负相关、与电导率极显著负相关、与孢子密度极显著正相关;Shannon-Weiner指数<em>H</em>与有机质极显著负相关;均匀度与有机质、孢子密度极显著负相关。厦门地区AM真菌资源十分丰富,多样性程度高,宿主植物不同,土壤因子对其侵染率、孢子密度、种的丰度、Shannon-Weiner指数、均匀度的影响也不同。为实现AM真菌生物技术应用于中药材规范化种植提供宝贵种质资源和理论依据。;The distribution, colonization rate and diversity of arbuscular mycorrhizal (AM) fungi in the rhizosphere of seven medicinal plants species in Xiamen, Fujian province were studied. The spores of AM fungi were isolated by modified method of wet sieving and decanting technique and identifled based on spore morphology and subcellular characters. The results showed a strong symbiotic relationship between seven medicinal plants and AM fungi. The highest spore density (29.0 cfu per g soil) was found in <em>Rhus chinensis</em> while the lowest (4.7 cfu per g soil) was in <em>Michelia figo</em>. Spores of <em>Gigaspora</em> occurred rarely and only in <em>Houttuynia cordata</em> Thunb., and <em>Scutellospora</em> only in <em>Rosa laevigata </em>Michx. <em>Glomus</em> <em>melanosporum</em> was most frequently associated with the 7 medicinal plants species. The highest mycorrhizal colonization (100%) was recorded in <em>Camptotheca acuminata</em> Decne while the lowest (4.5%) was in <em>Houttuynia cordata </em>Thunb. The results indicated that sixty three species of four genera of AM fungi were isolated, of which thirty-nine belonged to <em>Glomus</em>, eighteen to <em>Acaulospora</em>, two to <em>Scutellospora</em> and four to <em>Gigaspora</em>. Meanwhile, <em>Glomus </em>and <em>Acaulospora </em>were the dominant genera of the seven medicinal plants and <em>G. melanosporum</em>, <em>A. excavata</em>,<em> G. ambisporum</em>,<em> G. clarum</em>, and <em>G. geosporum</em> were the prevalent AM fungi. The highest species richness (26), Shannon-Wiener index (<em>H</em>) (2.29), and evenness (0.83) were found in <em>Rhus chinensis</em>, <em>Rosa laevigata </em>Michx., and <em>Mirabilis jalapa</em> Linn., in contrast to the lowest one in <em>Houttuynia cordata </em>Thunb.(9), <em>Houttuynia cordata </em>Thunb.(1.06) and <em>Rhus chinensis.</em>(0.39). The frequency (<em>F</em>) and importance value (<em>I</em>) of <em>Glomus</em> and <em>Acaulospora</em> in all the plants were higher than 50 percent. As the soil characteristic may play an important role in the ecological distribution of AM fungi, available P, available K, available N, organic matter, pH and electrical conductivity of the soil samples were investigated. In the present study, the colonization had no significant correlation with the soil factors. Spore density had a highly significantly negative correlation with pH values (<em>P</em>＜0.01). Species richness correlated significantly negatively with pH (<em>P</em>＜0.05), and had a highly significantly negative correlation with electrical conductivity, while highly positive correlation with spore density (<em>P</em>＜0.01). Shannon-Wiener index (<em>H</em>) had a highly significantly negative correlation with organic matter (<em>P</em>＜0.01). Evenness had a highly significantly negative correlations with soil organic matter and spore density (<em>P</em>＜0.01). These results indicated a high diversity of AM fungi in Xiamen. The effects of soil factors on colonization rate, spore density, species richness, Shannon-Wiener index (<em>H</em>) and evenness all varied with host plants. The colonization rate, spore density and species richness had negative correlations with pH values, available P, available N and electrical conductivity. The colonization rate and Shannon-Wiener index (<em>H</em>) had positive correlation with available K and evenness had positive correlation with available K, organic matter, pH and electrical conductivity. AM fungi may be a potent biological resource which can stimulate the growth of medicinal plants. This study provids a valuable germplasm and theoretical basis for AM fungal biotechnology to apply to medicinal standardization on planting.

Arbuscular mycorrhizal fungi (AMF) have the potential to increase crop productivity and play a key role in the functioning and sustainability of most agroecosystems. However, limited information is available on the divervisity of AMF associated with upland rice varieties in Southwest Nigeria. Field survey was conducted to investigate colonization and diversity of AMF in 13 upland rice varieties commonly grown in Southwest Nigeria. Root and soil samples were collected from rice fields in 2012. The results showed natural root colonization of all the rice varieties by AMF with highest root colonization in ITA 157and Ofada. The spore densities retrieved from the different rhizospheres were relatively high, varying from 13 spores in UORW 111 to 174 spores in Ofada with a mean of 67.6 spores per 20 g dry soil. Glomus was observed to be the most abundant AMF genus. Funneliformis mosseae was the most frequently occurring AMF species (96.2%) with relative density (RD) of 32.2%, followed by Glomus intraradices, Claroideoglomus etunicatum, and Glomus clareium. This study showed that AMF naturally colonized the roots of these rice varieties and diversity of different AMF genera in rice rhizosphere. This study will help draw attention to natural colonization of AMF in rice producing areas of Nigeria that can influence future possibility of using inocula of the dominant AMF species in upland rice cultivation.

ABSTRACTThe vertical diversity and distribution of arbuscular mycorrhizal (AM) fungi were investigated in the Mu Us Desert, northwest China. Soils were sampled to 50 cm in depth in the rhizospheres of Hedysarum laeve, Artemisia ordosica, and Psammochloa villosa and 44 AM fungal species belonging to 10 genera were isolated. Several of these species have peculiar morphological features, which are distinct from other habitats. AM fungal diversity and distribution differed significantly among the three host plants and the five soil layers. Spore density, species richness, and the Shannon-Wiener index of AM fungi were 0.55–4.3 spores g−1 soil, 7–36 and 1.78–2.89, respectively. Spore density and species richness had a significant positive correlation with soil total phosphorus content (0.0377–0.1129 mg g−1), and a negative correlation with soil pH (7.19–7.64). Nonmetric multidimensional scaling, PerMANOVA, and structural equation model analysis demonstrated that host plant species and soil depth significantly and directly influenced the structure of AM fungal communities. We concluded that diversity and distribution of AM fungi might be influenced by plant species, soil depth patterns, and soil nutrient availability in desert ecosystems. This research into AM fungal communities may lead to the development of AM fungi treatment for the mitigation of soil erosion and desertification using mycorrhizal plants, such as H. laeve, A. ordosica, and P. villosa.

Arbuscular Mycorrhizal Fungi (AMF) are ubiquitous soil microorganisms playing a vital role in the functioning of agricultural ecosystems. Although AMF are generally considered to have a low host specificity, it has been suggested that modern plant breeding has selected crop genotypes that are more selectively associated with AMF, possibly resulting in modern high yielding varieties (HYV) having a lower AMF diversity than traditional crop varieties. Whether this is true for paddy rice varieties under field conditions is not known so far. Here, we aimed at comparing differences of AMF communities among modern HYV and traditional rice varieties. We collected root and soil samples of five Bangladeshi rice varieties (two traditional and three modern HYV) from 40 different rice fields and quantified AMF richness, diversity and community composition through high throughput amplicon sequencing of the small subunit (SSU) of the ribosomal RNA cistron. Overall, 75 AMF OTUs, distributed over six AMF families with Glomeraceae as predominant family were found. After accounting for differences in soil conditions, we found that AMF diversity significantly differed among the five varieties and was higher in the traditional than modern varieties. The composition and structure of the AMF communities were distinct between the traditional and modern varieties. An indicator species analysis detected 9 OTUs significantly associated with traditional rice varieties, whereas no indicator OTUs were found for the modern HYV. We conclude that modern breeding coupled with high fertilizer application rates provide a plausible explanation for the reduced AMF diversity and the different AMF community composition between Bangladeshi modern HYV and traditional varieties.

Studies were carried out on spatio-temporal variations of arbuscular mycorrhizal (AM) fungi associated with Carica papaya L. growing in two different geographic localities in Goa, India – Western Ghats and coastal area, differing in soil characteristics and plantation status. The study recorded considerable variation in root colonization, spore density and distribution of AM fungi in the selected sites. The mean total root colonization was at a maximum in the month of July, while spore density was highest in April. The study recorded a total 33 species of AM fungi. Western Ghats recorded a relatively higher diversity of AM fungi compared to coastal area. Species richness of AM fungi was at a maximum in April and coincided with maximum mean spore density. Edaphic as well as climatic factors influenced the AM fungal parameters. The study recorded the existence of seasonality in AM fungi.

PDF HTML阅读 XML下载 导出引用 引用提醒 蒙古沙冬青及其伴生植物AM真菌物种多样性 DOI: 10.5846/stxb201609051806 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31170488，31270460） Species diversity of arbuscular mycorrhizal fungi in the rhizospheres of Ammopiptanthus mongolicus-associated plants Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:于2015年7月在内蒙古乌海、磴口2个样地选取蒙古沙冬青（Ammopiptanthus mongolicus）及其伴生植物为研究对象，分别采集0-20 cm和20-40 cm土层根围土样，利用高通量测序方法分析了不同植物AM真菌群落结构和物种多样性，发掘新物种，为补充和完善AM真菌分类体系提供依据。试验共分离鉴定3纲5目6科9属89个AM真菌OTU，属包括Glomus，Funneliformis，Diversispora，Claroideoglomus，Rhizophagus，Septoglomus，Scutellospora，Ambispora和Paraglomus。与形态学研究结果相比，高通量鉴定结果在属水平上更丰富。同一土层不同样地，蒙古沙冬青AM真菌丰度和多样性指数高于伴生植物；同一土层不同植物，AM真菌丰度和多样性指数表现为磴口高于乌海；同一植物不同样地，AM真菌ACE指数和Chao1指数20-40 cm土层高于0-20 cm土层，Simpson指数和Shannon指数0-20 cm土层高于20-40 cm土层。RDA分析表明，AM真菌ACE指数和Chao1指数与土壤碱解N显著正相关，与酸性磷酸酶显著负相关；Simpson指数和Shannon指数与碱性磷酸酶显著正相关，与pH显著负相关。结果表明，蒙古沙冬青AM真菌物种多样性高于伴生植物，同一样地，寄主植物与土壤深度共同作用对AM真菌群落组成有显著影响。 Abstract:Ammopiptanthus mongolicus is an endangered broadleaf leguminous plant found in the desert ecosystem of northwest China, and it is also an excellent sand fixation plant. Zygophyllum xanthoxylum, Tetraena mongolica, Nitraria Tangutorum and Artemisia desterorum are plants that associated with A. mongolicus. These plants undergo competition inhibition and cooperative evolution, and are ideal for improving desert areas and preventing desertification. Arbuscular mycorrhizal (AM) fungi can form symbioses with most terrestrial plant roots, and play an important role in improving plant growth and maintaining ecosystem stability. In order to discover new species and complement and improve the classification system of AM fungi, we used high-throughput sequencing to study species composition and the ecological distribution of AM fungi in the rhizosphere of Ammopiptanthus mongolicus and associated plants. Eighty-nine operational taxonomic units of AM fungi belonging to 5 classes, 3 orders, 6 families, and 9 genera including Glomus, Funneliformis, Diversispora, Claroideoglomus, Rhizophagus, Septoglomus, Scutellospora, Ambispora, and Paraglomus were identified. With regard to quantification at the genus level, high throughput sequencing was more sensitive than morphological evaluation. Ammopiptanthus mongolicus had a greater richness and diversity index than other associated plants. The ACE and Chao1 indices of AM fungi were higher in the 20-40 cm soil layer than in the 0-20 cm layer. However, the Simpson and Shannon indices were higher in the 0-20 cm layer. AM fungal abundance and diversity index were higher in Dengkou site than in Wuhai site. Redundancy analysis showed that the ACE and Chao1 indices of AM fungi were significantly positively correlated with soil-available N, but negatively correlated with acid phosphatase. Simpson and Shannon indices were significantly positively correlated with alkaline phosphatase, and significantly negatively correlated with pH. Together, these data show that the species diversity of AM fungi was higher in Ammopiptanthus mongolicus than in its associated plants. Furthermore, they reveal that interactions of host plant and soil depth had a significant effect on the community composition of AM fungi. 参考文献 相似文献 引证文献

The optimal growth and development of many vegetable crops hinge significantly upon their reliance on Arbuscular Mycorrhizal Fungi (AMF). Understanding the AMF status of vegetable crops can assist researchers in selecting suitable strains for future experiments. Therefore, a field work was carried out to determine the species diversity and composition of AMF with fifty vegetable crops from seventeen different districts of Haryana. AMF spores were isolated and identified to evaluate AMF density, diversity, and host preference in terms of AMF species richness, abundance and frequency of occurrence. Soil conditions, land use type and its physico–chemical properties played a crucial role in regulating the uneven distribution and composition of AMF. Mycotrophic structures such as linear infection (Arum–type) to coils (Paris–type) arbuscules and vesicles were seen. Interestingly, no correlation was found between spore number and root colonization. Maximum AMF spore density, spore richness and abundance were witnessed in Zea mays and Trigonella foenum–graecum. Five plants exhibited 100% AMF colonized roots, 15 plants showed above 75% and 12 plants above 50% colonization. Soil pH 6.10 to 7.40 supported the maximal abundance and frequency of occurrence of Glomus and Acaulospora with 53 species and 18 species followed by Acaulospora (18), Sclerocystis (10), Gigaspora (5), Entrophospora (4) and Sclerocystis (4). G. mosseae was the most preferred species among vegetable crops. Members of non–mycorrhizal families lack root colonization except for Brassica campestris, B. oleracea var. botrytis and B. Rapa where 2–11% root colonization was detected. Noticing the abundant AMF diversity of vegetable crops , this investigation expands the scope of detection, selection and inoculation of vegetable crops with suitable AMF species for improving their quality and quantity.

Elevated nitrogen (N) deposition may stimulate a plant’s dependency on arbuscular mycorrhizal (AM) fungi in phosphorus (P)-deficient subtropical forests. However, the ecological assembly processes and the responses of AM fungal diversity and community structure to N deposition in both the roots and rhizosphere are still unclear. We collected root and soil samples from a Cunninghamia lanceolata plantation forest after four years of N addition and examined the community structure and assembly of AM fungi. Elevated N deposition decreased the AM fungal community diversity in both rhizosphere soil and roots. Glomeraceae was the dominant family of the AM fungal community in both soil and roots across all N addition treatments, followed by Gigasporaceae and Ambisporaceae. However, N addition induced differential variation in the community composition of AM fungi between soil and roots. For soil AM fungi, N addition decreased the Glomeraceae abundance and increased the Gigasporaceae and Ambisporaceae abundance. In contrast, the root AM fungal community was dominated by Glomeraceae under N addition treatments. Furthermore, N addition increased the deterministic community assembly that acted as an environmental filter for soil AM fungi. In contrast, N addition decreased the importance of determinism, implying that the selection of plants on root AM fungi decreased with increasing N addition. Altogether, our findings suggest that the community structure of AM fungi responds differently to N deposition in the soil and roots in subtropical forests and highlight the important role of soil AM fungi in helping host plants respond to N deposition.

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

Arbuscular mycorrhizal (AM) fungi are important plant symbionts that provide plants with nutrients and water as well as support plant defences against pests and disease. Consequently, they present a promising alternative to using environmentally damaging and costly fertilisers and pesticides in agricultural systems. However, our limited understanding of how agricultural practices impact AM fungal diversity and functions is a key impediment to using them effectively in agriculture. We assessed how organic and conventional agricultural management systems shaped AM fungal communities. We also investigated how AM fungal communities derived from these agricultural management systems affected crop biomass and development. Six soil samples from five organically and five conventionally managed agricultural sites were used to cultivate Sorghum bicolor. Plant growth, plant nutrient concentrations and AM fungal colonisation rates were analysed alongside DNA metabarcoding of community composition. We observed that soil from conventional agricultural fields resulted in a pronounced reduction in sorghum biomass (−53.6%) and a significant delay in flowering compared to plants grown without AM fungi. Sorghum biomass was also reduced with soil from the organic system, but to a lesser extent (−30%) and without a delay in flowering. Organic systems were associated with a large proportion of AM fungal taxa (50.5% of VTs) not found in conventional systems, including Diversispora (r2 = 0.09, p &lt; 0.001), Archaeospora (r2 = 0.07, p &lt; 0.001) and Glomus (r2 = 0.25, p &lt; 0.001) spp., but also shared a large proportion of taxa with conventional systems (42.3% of VTs). Conventional systems had relatively few unique taxa (7.2% of VTs). Our results suggest that conventional agricultural practices selected against AM fungi that were, in this context, more beneficial for host plants. In contrast, organic management practices mitigate this negative effect, likely due to the presence of specific key AM fungal taxa. However, this mitigation is only partial, as less beneficial AM fungal taxa still persist, probably due to abiotic factors associated with agricultural management and the sensitivity of AM fungi to these factors. This persistence explains why the effect is not entirely eradicated. Read the free Plain Language Summary for this article on the Journal blog.

Activity, diversity and function of arbuscular mycorrhizae vary with changes in agricultural management intensity

Recent studies have shown that continuous cropping in soybean causes substantial changes to the microbial community in rhizosphere soil. In this study, we investigated the effects of continuous cropping for various time periods on the diversity of rhizosphere soil arbuscular mycorrhizal (AM) fungi in various soybean cultivars at the branching stage. The soybean cultivars Heinong 37 (an intermediate cultivar), Heinong 44 (a high-fat cultivar) and Heinong 48 (a high-protein cultivar) were seeded in a field and continuously cropped for two or three years. We analyzed the diversity of rhizosphere soil AM fungi of these soybean plants at the branching stage using morphological and denaturing gradient gel electrophoresis (DGGE) techniques. The clustering analysis of unweighted pair-group method with arithmetic averages (UPGMA) was then used to investigate the AM fungal community shifts. The results showed that increasing the number of years of continuous cropping can improve the colonization rate of AM fungi in different soybean cultivars at the branching stage. The dominant AM fungi in the experimental fields were Funneliformismosseae and Glomus spp. The number of years of continuous cropping and the soybean cultivar both had obvious effects on the diversity of AM fungi, which was consistent with the results of colonization rate analysis. This study establishes a basis for screening dominant AM fungi of soybean. In addition, the results of this study may be useful for the development of AM fungal inoculants.

James Hutton Institute, Dundee DD2 5DA, UKBelowground organisms, such as arbuscular mycorrhizal(AM) fungi, have long been credited with altering plant fit-ness. More recently, research on belowground organismshas revealed that AM fungi also influence a wide variety ofaboveground organisms via plants (reviewed in Van Dam H Bennett 2010). Schausberger et al. (2012) demon-strate that the presence of an AM fungus in the roots of ahost plant alters volatile emissions and host plant attractive-ness to parasitoids in the presence of herbivores. Thisextends previous studies that have focused on direct inter-actions of AM with plants (e.g. mycorrhizal fungal–plant–herbivore interactions; reviewed in Gehring & Bennett2009), but have not conclusively demonstrated how below-ground organisms, and AM fungi in particular, influencethird trophic level organisms such as parasitoids (Gange,Brown & Aplin 2003; Guerrieri et al. 2004; Hempel et al.2009; Leitner et al. 2010; Hoffmann, Vierheilig & Schaus-berger 2011a,b; Wooley & Paine 2011) via the release ofplant volatiles that attract parasitoids that attack herbivoreson host plants. Until recently, these studies failed to conclu-sively document the effects of AM fungi on both volatilerelease and attraction of parasitoids. For example, Wooley& Paine (2011) and Gange, Brown & Aplin (2003) haveshown variation in parasitoid attraction to plants hostingdifferent strains and species of Glomus as compared to non-mycorrhizal plants. Hoffmann, Vierheilig & Schausberger(2011a) also showed greater preference by parasitoids foreggs oviposited on plants associated with a single AMfungus. In addition, a single AM fungus in the roots of ahost plant has been shown to positively influence parasitoidlife-history characteristics (Hempel et al. 2009; Hoffmann,Vierheilig & Schausberger 2011b). However, none of thesestudies measured volatile profiles for host plants, so parasit-oid attraction could not be directly attributed to volatiles.A study on AM fungal influenced volatile release revealeddifferences but did not test whether changes in volatilesinfluenced parasitoids (Leitner et al. 2010). One study com-bined both parasitoid attractiveness and measurement ofvolatiles, but they primarily tested effects of attraction toplants in the absence of herbivory and never made compari-sons between mycorrhizal and non-mycorrhizal plantsexperiencing herbivory (Guerrieri et al. 2004). Unlike theseprevious experiments, Schausberger et al. measured bothchanges in volatile chemistry as well as parasitoid attractionin a fully factorial design.The results presented by Shausberger et al. open up multi-plefutureopportunitiesinabove–belowgroundresearch.Thefirst of these opportunities involves identifying the mecha-nisms by which AM fungi alter parasitoid attraction. Forexample,whatarethe biochemicalortranscriptionalchangesthat occur following AM fungal colonization that result inaltered volatile profiles? Are the mechanisms suggested forAM fungal alteration of direct chemical defences the samemechanisms that alter volatile profiles? Colonization by AMfungi has been shown to turn on the salicylic acid pathwaytemporarily,aprocessthatmayprimethejasmonicacidpath-way for herbivore attack (reviewed in Pozo & Azcon-Aguilar2007).Theinductionofvolatilesislinkedtothejasmonicacidpathway (reviewed in Heil 2008), and therefore, plants maybeprimedforafasterorgreaterreleaseofvolatileswhencolo-nizedbyAMfungi.However, there may be other mechanisms by which AMfungi influence volatile release. For example, given that AMfungi increase plant biomass and fitness in the PhaseolusvulgarissystemstudiedbyShausbergeret al.(aswellasmanyothersystems),itcouldsimplybethattheincreasedresourcesprovided by the mutualism allow plants to allocate moreresourcestoplantdefensivecharacteristics(e.g.directconstit-utiveandinduceddefencesaswellasindirectdefencesviavol-atile attraction; Bennett, Alers-Garcia & Bever 2006) or thatchanges in plant size or structure in association with AMfungi benefit or hinder parasitoid searching capabilities(Gange,Brown&Aplin2003).What characteristics of the volatile blends produced in thepresence of AM fungi are attractive for parasitoids? Shaus-bergeret al.showedtherewerefewerchemicalspresentinthevolatileblendsofAMfungalplantsbeforeherbivory(relativeto plants not hosting AM fungi), but this difference disap-peared after herbivory. However, different volatile chemicalswere released from plants experiencing herbivory and colo-nizedornotbyAMfungi(seealsoLeitneret al.2010).Shaus-berger et al. did not address whether increased attraction toplants hosting AM fungi is associated with a particular vola-

To understand the effects of agricultural management activities on soil arbuscular mycorrhizal (AM) fungi diversity, the high-throughput sequencing based on Illumina MiSeq platform, and the fatty acids fingerprints were used to examine the effects of maize straw returning on soil arbuscular mycorrhizal fungi. The relationships between AM fungal community composition, AM fungal biomass and soil factors after maize straw returning were examined for four continuous years. A total of 2430 operational taxonomic units (OTUs) of AM fungi were classified into 10 genera and 143 species, respectively, which belonged to 1 phylum, 3 classes, 4 orders, 8 families. There was no significant difference in AM fungal community richness (Chaoles index and ACE index) and diversity (Shannon, Simpson diversity indices) in different treatments. Paraglomus and Glomus were dominant genera among all AM fungal communities. With the increase of the maize straw returned amounts, the abundance of Glomus reduced. Under the treatments of 3000 and 9000 kg·hm-2 straw returned, the abundance of Glomus and Acaulospora had significant differences with the control (0 kg·hm-2). Compared with the control, there were significant differences between Archaeospora, Paraglomus and Glomus in the treatment of 3000 kg·hm-2 straw returned. Results from non-metric multi-dimensional scale (NMDS) analysis showed that under 9000 and 12000 kg·hm-2 straw returning treatments, the difference between the β diversity of soil AM fungi and the spatial distance of controls was farther apart than the other treatments. The effect of straw returning on the β diversity of AM fungi was significant. The multivariate analysis results revealed the relationship of the spatial variation between the soil physicochemical properties and AM fungi richness and diversity could be explained at 82.8% cumulative variables. The total nitrogen and available nitrogen were the most important factors driving soil microbial communities biomass marked by PLFAs and AM fungal biomass (NLFAs). The continuous maize straw returning to the field changed the genera composition of AM fungi. With the increases of straw returning amounts, the specific species of AM fungi decreased and the similarity between AM fungi community composition decreased. Straw returning increased soil AM fungi biomass and its contribution to soil total microbial biomass.