Arbuscular mycorrhizal fungi assemblages in Chernozem great groups revealed by massively parallel pyrosequencing

The molecular diversity of arbuscular mycorrhizal (AM) fungi remains largely unexplored in sedge-dominated ecosystems, much less their responses to global climate change and grazing. To determine the molecular diversity of AM fungi and how they are affected by climate change and grazing, we examined AM fungal communities inside roots in a sedge meadow ecosystem (4875 m a.s.l.) undergoing 4 yr. of fully factorial manipulations of experimental warming, snow addition and grazing on the Tibetan Plateau. A total of 21 AM fungal virtual taxa (VTs) were identified, including one new genus-like clade and one new VT unrecorded in the MaarjAM database. However, we did not observe significant effects of climate change and/or grazing on AM fungal abundance, diversity and community composition. These results indicate that diverse AM fungal taxa inhabit in the sedge-dominated meadows on the Tibetan Plateau, but the AM fungal communities were not sensitive to short-term climate change and grazing.

The diversity and abundance of arbuscular mycorrhizal fungi (AMF) was assessed in the Kumaon Himalayan foothills. Four typical ecosystems were selected in the Sat-Tal area located in the Nainital, district in Uttarakhand, India, representing vegetation change due to human settlement and selective logging of native oak. Besides a natural oak forest, a mixed pine-oak forest, a pure pine stand and an arable field were sampled. The latter was cropped with black gram (Vigna mungo L. Hepper) and maize (Zea mays L.) during the rainy season from June to September and rotated with wheat (Triticum aestivum L.) during winter for the last 10 years. Only cow dung compost used for fertilization. The highest AMF spore abundance throughout the year was recorded in soil samples from the pine-oak mixed forest, followed by the pine and oak forests and the agricultural field. At all sites, the lowest spore abundance was recorded at the end of the winter season in March, and the highest in October after the rainy season. Whereas in October, Glomus claroideum, Acaulospora scrobiculata and A. spinosa were found at all sites, in March it was only G. intraradices which occurred everywhere. The highest AMF spore morphotype richness was recorded in samples from the oak forest. In AMF-trap cultures set up with field soil inocula, the dominant species recovered were G. intraradices, G. etunicatum and A. scrobiculata. As compared to the field samples, trap culturing of one year enhanced spore abundance but entailed a loss of AMF richness. The study revealed differences in AMF Research Article British Microbiology Research Journal, 2(2): 82-96, 2012 83 community composition and structure among sites characterized by different land use systems.

We investigated arbuscular mycorrhizal (AM) fungal communities in secondary forests and/or Chamaecyparis obtusa plantations at eight study sites in Japan's temperate region. In the secondary forests, AM plants of the families Lauraceae, Sapindaceae, Rutaceae, Araliaceae, Rosaceae, Magnoliaceae, Cornaceae, Piperaceae, and Anacardiaceae were found. The AM fungal communities were evaluated based on compositions of the AM fungal operational taxonomic units (OTUs), which were clustered at a 97% similarity threshold of the sequences of a partial small subunit of a nuclear ribosomal RNA gene obtained from the plant roots. The compositions of AM fungal OTUs were significantly correlated with the plant family compositions and were significantly differentiated among the study sites and between the study forests. Interestingly, only 19 OTUs remained after selecting for those that had more than 1.0% of the total reads, and these 19 OTUs accounted for 86.3% of the total rarefied reads that were classified into 121 OTUs. Furthermore, three dominant OTUs constituted 48.0% of the total reads, and the most dominant OTU was found at all study sites, except at one. These results indicate that AM fungal communities are primarily constituted by limited AM fungal taxa in the forest ecosystems with diverse plant taxa in Japan's temperate region. The results of basic local algorithm search tool (BLAST) searches against MaarjAM, a database of AM fungal sequences, also revealed that the AM fungi which were the three dominant OTUs are distributed in forest ecosystems on a worldwide scale.

Changes in arbuscular mycorrhizal fungal attributes along a chronosequence of black locust (Robinia pseudoacacia) plantations can be attributed to the plantation-induced variation in soil properties

The hidden Serengeti—Mycorrhizal fungi respond to environmental gradients

Elucidating the diversity of native arbuscular mycorrhizal (AM) fungi is essential for the sustainable management of semi-arid land ecosystems. This is because they significantly improve plant nutrient uptake and decrease the stress caused by biotic and abiotic factors. In this study, we examined the AM fungal communities and the key drivers influencing their diversity and occurrence in the smallholder farming systems of Eastern Kenya. Soils samples were collected from 34 diverse agricultural fields and AM fungal spores were extracted using wet-sieving and decantation techniques. The spores were quantified, and AM fungal communities were identified based on their morphological characteristics. Statistical data analyses, including relative abundance, the Shannon-Wiener index, analysis of variance (ANOVA), and principal component analysis (PCA), were performed using R software 4.4.0. The results revealed that two AM fungal families dominated the agricultural fields, namely Gigasporaceae (61.0%) and Acaulosporaceae (39.0%). These fungal families comprised a total of five genera, with the following relative abundances: Acaulospora (39.0%), Gigaspora (35.05%), Scutellospora (23.92%), Dentiscutata (1.32%), and Rococetra (0.72%). The AM fungal morpho-species were ranked from 1 to 26 across the five genera. Acaulospora denticulata ranked the highest, with a proportion of 25.19%. The Shannon-Wiener diversity index revealed a higher diversity of AM fungi in agricultural fields with greater spore richness. The PCA showed that the composition of AM fungal communities was strongly related to soil physiochemical characteristics. Dryland farming systems also played a role in AM fungal composition. Overall, the distribution of AM fungal communities across the agricultural fields was lower, implying the need to adopt sustainable dryland farming systems to enhance native AM fungal communities and support the development of context-specific biofertilizers.

Qatar is largely characterized by a hyper-arid climate and low soil fertility which create a stressful soil environment for arbuscular mycorrhizal (AM) fungi. In a study of AM fungal communities and their relationship with soil chemical characteristics, we used a high-throughput sequencing technique to explore AM fungal diversity and community composition in different habitats across Qatar. We identified a total of 79 AM fungal taxa, over 77% of which were species from the Glomeraceae family. The lowest AM fungal diversity was observed in saltmarsh and in one rawdha site, while the highest richness, effective number of species, and diversity were observed in rawdha and sabkha communities. NMDS and multiple regression analyses showed that AM fungi were negatively correlated with soil pH and TC, but positively correlated with K and NO3-. AM fungi also were positively correlated with Cd, with the latter suggesting that very low levels of heavy metals may not always be harmful to AM fungi. These findings provide baseline information on AM fungal assemblages and the chemical drivers of diversity across communities in Qatar. This work partly compensates for the current lack of broad-scale studies in the Arabian Peninsula by providing understanding of overall patterns of AM fungi and their drivers in the region.

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.

Understanding the response of arbuscular mycorrhizal (AM) fungi to warming and nitrogen (N) fertilization is critical to assess the impact of anthropogenic disturbance on ecosystem functioning under global climate change scenarios. In this study, AM fungal communities were examined in a full factorial design with warming and N addition in a semiarid steppe in northern China. Warming significantly increased AM fungal spore density, regardless of N addition, whilst N addition significantly decreased AM fungal extraradical hyphal density, regardless of warming. A total of 79 operational taxonomic units (OTUs) of AM fungi were recovered by 454 pyrosequencing of SSU rDNA. Warming, but not N addition, had a significant positive effect on AM fungal OTU richness, while warming and N addition significantly increased AM fungal Shannon diversity index. N addition, but not warming, significantly altered the AM fungal community composition. Furthermore, the changes in AM fungal community composition were associated with shifts in plant community composition indirectly caused by N addition. These findings highlight the different effects of warming and N addition on AM fungal communities and contribute to understanding AM fungal community responses to global environmental change scenarios in semiarid steppe ecosystems.

Influence of plant communities and soil properties during natural vegetation restoration on arbuscular mycorrhizal fungal communities in a karst region

Arbuscular mycorrhizal (AM) fungi play important roles in carbon (C), nitrogen (N) and phosphorus (P) cycling of terrestrial ecosystems. The impact of increasing N deposition on AM fungi will inevitably affect ecosystem processes. However, generalizable patterns of how N deposition affects AM fungi remains poorly understood. Here we conducted a global-scale meta-analysis from 94 publications and 101 sites to investigate the responses of AM fungi to N addition, including abundance in both intra-radical (host roots) and extra-radical portion (soil), richness and diversity. We also explored the mechanisms of N addition affecting AM fungi by the trait-based guilds method. Results showed that N addition significantly decreased AM fungal overall abundance (-8.0%). However, the response of abundance in intra-radical portion was not consistent with that in extra-radical portion: root colonization decreased (-11.6%) significantly, whereas extra-radical hyphae length density did not change significantly. Different AM fungal guilds showed different responses to N addition: both the abundance (spore density) and relative abundance of the rhizophilic guild decreased significantly under N addition (-29.8% and -12.0%, respectively), while the abundance and relative abundance of the edaphophilic guild had insignificant response to N addition. Such inconsistent responses of rhizophilic and edaphophilic guilds were mainly moderated by the change of soil pH and the response of root biomass, respectively. Moreover, N addition had an insignificant negative effect on AM fungal richness and diversity, which was strongly related with the relative availability of soil P (i.e. soil available N/P ratio). Collectively, this meta-analysis highlights that considering trait-based AM fungal guilds, soil P availability and host plant C allocation can greatly improve our understanding of the nuanced dynamics of AM fungal communities under increasing N deposition.

Plant and arbuscular mycorrhizal (AM) fungal diversity are both positively linked to ecosystem productivity across diverse ecosystems. However, given their high sensitivity to climate extremes such as extreme drought, the persistence and adaptability of these diversity-productivity relationships under rapid climate changes remain poorly understood. To address this, we established a grassland experiment at two proximate sites with distinct natural plant and AM fungal communities, imposing two contrasting extreme drought regimes (intense and chronic), each exceeding a 20-year recurrence interval based on site-specific precipitation records. We show that AM fungal diversity consistently outperforms plant diversity in predicting plant aboveground/net primary productivity (ANPP/NPP), as well as compositional shifts in plant species productivity, despite pronounced drought sensitivity in both communities. Notably, enhanced drought resistance in plant productivity was primarily associated with the stability of AM fungal richness rather than plant richness, highlighting their mutual dependence under extreme drought. Structural equation modelling confirmed that AM fungal richness buffered drought effects on ANPP, NPP and plant richness, with stronger effects on ANPP and NPP than those of plant richness and soil properties. These results suggest that AM fungal diversity may play a greater role than plant diversity in buffering plant communities against climate extremes. While causality remains to be fully resolved, these findings shed light on the adaptive significance of this ancient symbiont in sustaining ecosystem functioning under rapid climate change.

Effects of nicosulfuron on the abundance and diversity of arbuscular mycorrhizal fungi used as indicators of pesticide soil microbial toxicity

Background: Arbuscular mycorrhizal fungi (AMF) generate a symbiotic relationship with most terrestrial plants, influencing the dynamics and functioning of ecosystems. There are few studies on the diversity of these fungi associated with forest species and in different types of ecosystems. The objective of this study was to characterize the diversity and structure of AMF communities associated with Cordia alliodora and Swietenia macrophylla in two forestry ecosystems with different types of management in Costa Rica. For this purpose, rhizosphere and soil samples were collected from 10 trees at random, spores and sporocarps were isolated and characterized, AMF abundance, richness and diversity were determined, and a physicochemical analysis of the soil was carried out. Results: Fifty-seven AMF morphospecies belonging to five orders, 10 families and 15 genera were identified, with a predominance of Diversisporales and Glomerales; we report 15 new geographic records of AMF increasing the richness to 76 species and by 24% the Glomeromycota’s richness in Costa Rica. There were no significant differences in total spore abundance between the two forest species, however, there were significant differences in the modes of formation and species composition. Conclusions: The alpha diversity analysis showed that rare species largely explain the differences between the sites, and the AMF community structure was influenced by edaphic factors such as pH and available phosphorus content. These types of studies highlight the importance of considering the identity and diversity of AMF associated with forest species of commercial interest and ecological importance in different types of ecosystems.

Nutrient loss from ecosystems is among the top environmental threats to ecosystems worldwide, leading to reduced plant productivity in nutrient-poor ecosystems and eutrophication of surface water near nutrient-rich ecosystems. Hence, it is of pivotal importance to understand which factors influence nutrient loss. Here it is demonstrated that arbuscular mycorrhizal (AM) fungi, widespread soil fungi that form mutualistic relationships with the majority of land plants, reduce nutrient loss from grassland microcosms during rain-induced leaching events. Grassland microcosms with AM fungi lost 60% less phosphorus and 7.5% less ammonium compared to control microcosms without AM fungi. Similar results were obtained for microcosms planted with each of three different grass species. In contrast, nitrate leaching was not affected by AM fungi but depended on the amount of nutrients supplied to the microcosms. Moreover, fertilization of the microcosms reduced the abundance of AM fungi and their ability to reduce phosphorus leaching losses. Extrapolation of these results suggests that the disruption of the mycorrhizal symbiosis is one of the reasons for enhanced phosphorus loss from fertilized ecosystems. The microcosms contained a sandy soil, a soil type vulnerable to leaching losses. The reduction of phosphorus leaching by AM fungi may, therefore, represent an upper limit. Advantages and limitations of the experimental setup for assessing the impact of AM fungi on nutrient cycling are discussed. The results indicate that AM fungi contribute to ecosystem sustainability by promoting a closed phosphorus cycle and reducing phosphorus leaching losses.