Synergy Between Agroecological Practices and Arbuscular Mycorrhizal Fungi

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.

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

Arbuscular mycorrhizal fungus identity and diversity influence subtropical tree competition

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.

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.

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

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.

With the development of agriculture and industry, the increase in nitrogen (N) deposition has caused widespread concern among scientists. Although emission reduction policies have slowed N releases in Europe and North America, the threat to biodiversity cannot be ignored. Arbuscular mycorrhizal (AM) fungi play an important role in the establishment and maintenance of plant communities in forest ecosystems, and both their distribution and diversity have vital ecological functions. Therefore, we analyzed the effects of long-term N addition on AM fungi and understory herbaceous plants in a Korean pine plantation in northern China. The soil properties, community structure, and diversity of AM fungi and understory herbaceous plants were detected at different concentrations of NH4NO3 (0, 20, 40, 80 kg N ha−1 year−1) after 7 years. The results showed that long-term N deposition decreased soil pH, increased soil ammonium content, and caused significant fluctuations in P elements. N deposition improved the stability of soil aggregates by increasing the content of glomalin-related soil protein (GRSP) and changed the AM fungal community composition. The Glomus genus was more adaptable to the acidic soil treated with the highest N concentration. The species of AM fungi, understory herbaceous plants, and the biomass of fine roots were decreased under long-term N deposition. The fine root biomass was reduced by 78.6% in the highest N concentration treatment. In summary, we concluded that long-term N deposition could alter soil pH, the distribution of N, P elements, and the soil aggregate fractions, and reduce AM fungal and understory herb diversity. The importance of AM fungi in maintaining forest ecosystem diversity was verified under long-term N deposition.

Morphology and colonization preference of arbuscular mycorrhizal fungi in &lt;i&gt;Clethra barbinervis&lt;/i&gt;, &lt;i&gt;Cucumis sativus&lt;/i&gt;, and &lt;i&gt;Lycopersicon esculentum&lt;/i&gt;

The arbuscular mycorrhizal (AM) fungal resources present in wheat fields of the Canadian Prairie were explored using 454 pyrosequencing. Of the 33 dominant AM fungal operational taxonomic units (OTUs) found in the 76 wheat fields surveyed at anthesis in 2009, 14 clustered as Funneliformis - Rhizophagus, 16 as Claroideoglomus, and 3 as Diversisporales. An OTU of Funneliformis mosseae and one OTU of Diversisporales each accounted for approximately 16% of all AM fungal OTUs. The former was ubiquitous, and the latter was mainly restricted to the Black and Dark Brown Chernozems. AM fungal OTU community composition was better explained by the Chernozem great groups (P = 0.044) than by measured soil properties. Fifty-two percent of the AM fungal OTUs were unrelated to measured soil properties. Black Chernozems hosted the largest AM fungal OTU diversity and almost twice the number of AM fungal sequences seen in Dark Brown Chernozems, the great group ranking second for AM fungal sequence abundance. Brown Chernozems hosted the lowest AM fungal abundance and an AM fungal diversity as low as that seen in Gray soils. We concluded that Black Chernozems are most conducive to AM fungal proliferation. AM fungi are generally distributed according to Chernozem great groups in the Canadian Prairie, although some taxa are evenly distributed in all soil groups.

The Tansley review by Ryan & Graham (2018) provided a welcome critical perspective on the role of arbuscular mycorrhizal (AM) fungi in large‐scale industrial agriculture, with a focus on cereals (wheat, Triticum aestivum). They conclude that there is little evidence that farmers should consider the abundance or diversity of AM fungi when managing crops. We welcome many of the points made in the paper, as they give an opportunity for self‐reflection, considering that the importance of AM fungi in agroecosystems is often taken for granted. However, we suggest that it is too early to draw the overall conclusion that the management of AM fungi by farmers is currently not warranted. We offer the following points to contribute to the discussion. The first point pertains to the overall focus of Ryan & Graham (2018), which strongly determines the recommendations at which the authors arrive. This scope is limited to yield, at the expense of neglecting aspects of sustainability. We then argue that AM fungal communities do respond negatively to aspects of agricultural management, and list evidence for their positive effects to agronomically important traits, including yield in cereals. In our final argument, we advocate for transitioning to agroecosystems that are more AM compatible in order to increasingly take advantage of all the potential services these ancient symbionts, and other soil biota, can provide.

The aim of the study was to explore whether the encroachment of an East-African savannah ecosystem by the invasive shrub Dichrostachys cinerea L. Wight & Arn has resulted in changes in the Arbuscular Mycorrhizal Fungus (AMF) communities which are associated with roots of the extant herbaceous plant communities. We hypothesized that this could happen either through introducing new AMF taxa, or through inducing changes in the savannah soil environment or plant community composition. We selected five blocks in the savannah plains of the Nech Sar National Park, southern Ethiopia, and in each block, we established nine vegetation plots along a gradient of D. cinerea encroachment. We sampled roots from the encroaching shrub D. cinerea and from three dominant graminoids (Brachiaria deflexa, Chrysopogon plumulosus, Lintonia nutans) and two forbs (Commelina forskaolii, Ruellia prostrata), and used a metagenomics approach to identify the AMF taxa associated with their roots. D. cinerea exhibited higher AMF richness and diversity, and a significantly different AMF community composition, compared with the sampled herbaceous plants in the unencroached plots. Herbaceous plants in sparsely encroached plots harbored a higher AMF diversity as compared to the control plots, while those in densely encroached plots exhibited an intermediate AMF diversity. D. cinerea encroachment, host plant lifeform, soil characteristics and extant herbaceous plant species diversity all affected AMF community composition associated with the herbaceous plant roots. Woody encroachment might have affected AMF communities of the extant herbaceous vegetation in savannah ecosystems both directly, through introducing novel AMF taxa associated with the encroaching shrub species, and indirectly, through encroachment effects on the environment. Restoration of encroached savannahs should therefore take into account the legacy effects of the invader on the microbial communities.

Arbuscular mycorrhizal fungi changes by afforestation in sand dunes

The hidden Serengeti—Mycorrhizal fungi respond to environmental gradients

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.