Mycorrhizal Research Articles

Higher temperatures decreased the abundance of arbuscular mycorrhizal fungi and the complexity of their networks by reducing tree diversity

Higher temperatures decreased the abundance of arbuscular mycorrhizal fungi and the complexity of their networks by reducing tree diversity

Arbuscular mycorrhizal fungi enhance drought resistance and alter microbial communities in maize rhizosphere soil

Although the benefits of inoculation with arbuscular mycorrhizal fungi (AMF) for mitigating drought stress and enhancing plant growth of host are well‐studied, our understanding of their interactions with soil attributes and rhizosphere microbial communities remains limited. In the present study, we conducted a pot experiment to explore how AMF affects maize growth, antioxidant activity, soil properties, and the rhizosphere microbial communities under drought stress. The results showed that AMF inoculation during drought stress resulted in improved maize seedling growth, significantly increasing plant biomass (42.7%), chlorophyll content (13.4%), and antioxidant capacity. It also enhanced soil nutrient availability and microbial biomass. We observed significant shifts in the structure and composition of the rhizosphere microbial community with AMF inoculation under drought conditions when compared to those under well-watered conditions. Significantly, bacterial diversity and composition showed greater sensitivity to drought stress than fungal communities. This was attributed to plants preferentially reducing the supply of carbon sources to bacterial rather than to fungal communities under drought conditions. AMF inoculation also enhanced the complexity (e.g., degree) and stability of the rhizosphere microbial ecological network, suggesting closer ecological interactions within the soil microbial community. Furthermore, bacterial diversity and richness played a more important role in soil function than those of fungal communities under drought stress, particularly with AMF inoculation. Overall, our findings suggest that AMF inoculation alters soil microbial diversity and interactions, highlighting their key roles in enhancing plant stress tolerance and mitigating the negative effects of drought on agricultural ecosystems.

Metabolomics analysis reveals crucial effects of arbuscular mycorrhizal fungi on the metabolism of quality compounds in shoots and roots of Camellia sinensis L

Metabolomics analysis reveals crucial effects of arbuscular mycorrhizal fungi on the metabolism of quality compounds in shoots and roots of Camellia sinensis L

Plant-microbiome interactions for enhanced crop production under cadmium stress: A review.

Cadmium (Cd) is a toxic heavy metal that has detrimental effects on agriculture crops and human health. Both natural and anthropogenic processes release Cd into the environment, elevating its contents in soils. Under Cd stress, strong plant-microbiome interactions are important in improving crop production, but a systematic review is still missing. This review demonstrates the importance of microbiomes and their interactions with plants in mitigating Cd toxicity and promoting crop growth. Endogenous and exogenous microbiomes play a role to enhance plant's ability to respond to Cd stress. Specifically, the rhizosphere microbiome, which includes plant growth-promoting rhizobacteria and arbuscular mycorrhizal fungi, endosphere microbiome, and phyllosphere microbiome, are involved in Cd accumulation, immobilization, and translocation, and Cd-induced stress management. The mechanisms underlying these plant-microbiome interactions vary depending on the species and varieties of crops, composition and diversity of the microbiome, and level of Cd stress. Among the microbiome-mediated approaches, biosorption, bioprecipitation, and bioaccumulation are promising for Cd remediation in soil. Additionally, the endosphere microbiome, particularly Cd resistant endophytes, reduces Cd toxicity, increases the expression of Cd efflux genes, and enhances crop growth through regulating crops' antioxidant machinery and endogenous hormones. Furthermore, improved agricultural practices modulate the soil and plant microbiomes, thereby reducing Cd stress and increasing crop productivity.

Interactions of silicon and arbuscular mycorrhizal fungi on phosphorus uptake during rice vegetative growth

Interactions of silicon and arbuscular mycorrhizal fungi on phosphorus uptake during rice vegetative growth

NO3--N pulse supply caused by biodegradable plastics exacerbates Trifolium repens L. invasion.

The exacerbation of plant invasion by microplastics attracted widespread attention. Pulse resource hypothesis is popular theory to elucidate plant invasion. Our previous work demonstrated biodegradable microplastics (BMPs) could increase the arbuscular mycorrhizal fungi (AMF) colonization rate. Reportedly, AMF can enhance rhizobia colonization. Therefore, we infer the coexistence of BMPs with legumes may lead to an increased colonization of rhizobia with negative feedback regulation of N fixation. This could result in NO3--N pulse supply, thereby exacerbating plant invasion. Subsequently, a 60-day pot experiment was conducted using Trifolium repens L. as invasive plant and Oxalis corniculata L. as native plant, with 1% or 5% wt BMPs. AMF colonization, BMPs degradation, NO3--N content and pulse supply, rhizobia colonization, relative competitive intensity, replacement diagrams and NO3--N utilization were determined. The mechanism was clarified through heat map and structural equation model. The results reveal the greater the NO3--N consumption by BMPs, the more AMF promoted rhizobia colonization in T. repens, thereby the larger the pulse amplitude of NO3--N supply, then, the higher the NO3--N utilization rate of T. repens. It exacerbates T. repens invasion. This study clarifies effects of BMPs on rhizobia's N fixation, and enriches the evidence on mechanism of BMPs exacerbating plant invasion.

Synergistic effect of arbuscular mycorrhizal fungi, biochar and seaweed extract for improving the copper tolerance in hemp

Synergistic effect of arbuscular mycorrhizal fungi, biochar and seaweed extract for improving the copper tolerance in hemp

Enhancement of alfalfa growth resistance by arbuscular mycorrhiza and earthworm in molybdenum-contaminated soils: From the perspective of soil nutrient turnover.

Molybdenum (Mo) acts as a crucial nutrient for plant development, yet excessive soil exposure can cause detrimental effects. Molybdenosis symptoms remain subtle in many plants, largely due to the safeguarding functions of soil organisms, the fundamental biological mechanisms lack clarity. In this study, we explored the potential mechanisms for amending Mo-exposed soils with soil microbe-arbuscular mycorrhizal fungi (AMF) and soil fauna, specifically earthworms, to enhance model plant-alfalfa growth resistance through soil nutrient turnover perspectives. Our findings illustrated that excessive Mo exposure disrupted soil nutrient turnover, manifesting as exacerbated microbial C and N metabolic limitations. Consequently, this interference intensified nutrient competition between alfalfa and soil microbes, thereby impeding alfalfa nutrient uptake and growth resistance. The synergistic application of AMF and earthworms alleviated microbial C (8.55% ∼ 28.23%) and N (11.14% ∼ 37.55%) metabolic limitations by modulating soil enzyme activities, particularly P-acquiring enzyme. This co-approach facilitated enhanced C and N accumulation in alfalfa, thus improving its growth resistance (24.15% ∼ 123.74%) under Mo exposure. Furthermore, in contrast to singular treatments, the combination of AMF and earthworms bolstered mutual Mo tolerance, amplifying biological benefits for alfalfa growth. Earthworms promoted AMF colonization and the secretion of glomalin-related soil proteins (GRSP), while AMF alleviated Mo accumulation and oxidative stress in earthworms. Additionally, the AMF-induced regulation of gut metabolism reduced earthworm mortality and minimized weight loss. Our study underscores the necessity of maintaining soil biodiversity when utilizing Mo fertilizers to mitigate the potential risks of Mo over-exposure affecting soil nutrient turnover and plant growth.

Commercial bioinoculants improve colonization but do not alter the arbuscular mycorrhizal fungal community of greenhouse-grown grapevine roots

BackgroundArbuscular mycorrhizal fungi (AMF) are beneficial root symbionts contributing to improved plant growth and development and resistance to abiotic and biotic stresses. Commercial bioinoculants containing AMF are widely considered as an alternative to agrochemicals in vineyards. However, their effects on grapevine plants grown in soil containing native communities of AMF are still poorly understood. In a greenhouse experiment, we evaluated the influence of five different bioinoculants on the composition of native AMF communities of young Cabernet Sauvignon vines grown in a non-sterile soil. Root colonization, leaf nitrogen concentration, plant biomass and root morphology were assessed, and AMF communities of inoculated and non-inoculated grapevine roots were profiled using high-throughput sequencing.ResultsContrary to our predictions, no differences in the microbiome of plants exposed to native AMF communities versus commercial AMF bioinoculants + native AMF communities were detected in roots. However, inoculation induced positive changes in root traits as well as increased AMF colonization, plant biomass, and leaf nitrogen. Most of these desirable functional traits were positively correlated with the relative abundance of operational taxonomic units identified as Glomus, Rhizophagus and Claroideoglomus genera.ConclusionThese results suggest synergistic interactions between commercial AMF bioinoculants and native AMF communities of roots to promote grapevine growth. Long-term studies with further genomics, metabolomics and physiological research are needed to provide a deeper understanding of the symbiotic interaction among grapevine roots, bioinoculants and natural AMF communities and their role to promote plant adaptation to current environmental concerns.

Arbuscular and fine root-endophytic mycorrhizal fungi forage differently for nutrients in a seminatural temperate grassland

Abstract The acquisition of P and N from soil and their exchange for fixed C are key functions of mycorrhizal fungi in their symbiotic relationship with host plants. Additional contribution to plant nutrition is possible when hyphae proliferate into soil space not directly accessible to plant roots or when they locate nutrient-rich patches more effectively than plant roots. We performed a field-based experiment in a seminatural grassland. Community composition, diversity, and root colonisation intensity of mycorrhizal fungi was compared across different types of substrate patches (enriched or not with inorganic N, P or both), between two exposure times, and with unmanipulated soil and patches enriched with plant biomass. Beside evaluating the response of the communities of arbuscular mycorrhizal fungi (G-AMF) and fine root endophytes (M-FRE), we estimated foraging speed and precision of multiple taxa within these two groups. We compared the relative abundance of both groups using molecular barcoding. While G-AMF responded in community composition and diversity to inorganic and organic N enrichment, M-FRE did not discriminate among diferentially nutrient-enriched patches. Individual taxa varied in foraging response, but G-AMF were slower and possibly more discriminatory than M-FRE in occupying patches differing in N and/or P-enrichment. Particularly two virtual taxa of the Rhizophagus irregularis morphospecies of the G-AMF grew preferentially into the N-enriched patches. We thus conclude that there exist important differences in the strategies of soil exploration for nutrients within both fungal groups.

An assessment of plant growth and physiological responses in annual crops grown in P deficient soils inoculated with indigenous arbuscular mycorrhizal fungi.

The influence of arbuscular mycorrhizal fungi (AMF) inoculation on the growth and physiology of Phaseolus vulgaris L. and Zea mays L. in the Brazilian tropical seasonal dry forest is not well known. We examined the effects of indigenous AMF species inoculation on these two annual crops at phosphorus-deficient soils under glasshouse conditions. The AMF species used as inoculum were collected from the root zone of Mimosa tenuiflora, a native plant of the Caatinga ecoregion. The inoculum was propagated in plastic pots with Trifolium sp. as the host plant. We investigated the effect of four treatments: (1) Control- non-inoculated; (2) Acaulospora inoculum- inoculation with A. tuberculata; (3) Gigaspora inoculum- inoculation with G. gigantea; and (4) Mixed inoculum- inoculation with both Acaulospora and Gigaspora species. We found that inoculation with the indigenous AMF community enhanced plant dry biomass, plant P concentration, root colonization, and physiological responses for both model plants. This study highlighted the importance of exploring the P molecule as an integral element in plant development and presents the AMF inoculation as an efficient alternative to overcome low-P conditions, leading to improved nutrient acquisition in low-fertility soils, better growth conditions through enhanced physiological responses, and ultimately increased plant dry biomass.

Efficient degradation of neomycin by Bacillus velezensis and Cupriavidus basilensis isolated from mangrove soil and pharmaceutical wastewater

Neomycin, an aminoglycoside antibiotic, is widely utilized for veterinary medicine in disease prevention. Biodegradation is a key pathway for the removal of neomycin from the environment. To date, only the white-rot fungus Trametes versicolor and the ericoid mycorrhizal fungus Rhizoscyphus ericae have been documented to efficiently degrade neomycin. However, no bacterial species with neomycin-degrading capabilities have been reported, underscoring a significant gap in microbial research related to neomycin remediation. In this study, Cupriavidus basilensis and Bacillus velezensis were isolated from pharmaceutical wastewater and neomycin-free mangrove soil through enrichment culture and gradual acclimatization, respectively. These isolates demonstrated neomycin degradation rates of 46.4 and 37.6% in 96 h with 100 mg·L−1 neomycin as the sole carbon source. Cupriavidus basilensis achieved a degradation rate of 50.83% with ammonium sulfate supplementation, while Bacillus velezensis exhibited a superior degradation efficiency of 58.44% with soluble starch. Our findings offer valuable insights into the microbial degradation of neomycin. Two neomycin-degrading bacteria were isolated for the first time. Both species degraded neomycin as the sole carbon source or under co-metabolic conditions within 4 days. Microorganisms from neomycin-free environments adapted to neomycin stress and outperformed those from contaminated sources. This challenges the assumption that antibiotic-degrading microorganisms mainly originate from polluted environments. The findings expand the diversity of known neomycin-degrading microorganisms and demonstrate their potential for removing refractory neomycin from pharmaceutical wastewater.

The potential of arbuscular mycorrhizal fungi to improve soil organic carbon agricultural ecosystems: A meta‐analytical approach

Abstract Increasing soil organic carbon (SOC) in agroecosystems is a key objective for enhancing agricultural sustainability and mitigating climate change. Arbuscular mycorrhizal fungi (AMF) can increase yield and provide several other ecosystem services. Still, studies conducted in agricultural soils have shown that their effects on SOC can be either positive, neutral or negative. In this study, we conducted a quantitative review of the literature to evaluate the role of AMF in influencing SOC across various crop species and conditions. Through a systematic search of publications, we compiled a dataset comprising 62 trials from 19 studies including field and pot experiments that directly manipulated the mycorrhizal status of plants. We conducted a meta‐analysis to quantitatively evaluate the role of AMF on SOC across several crop species and conditions. We found an overall positive effect of AMF on SOC, with an average increase of 21.5%. However, this positive effect was statistically significant only in pot experiments whereas in field experiments, the effect was mainly modulated by texture and organic matter content. The effect of AMF on SOC did not vary with crop species' functional type, AMF inoculation sources (single or mixed AMF species) or other soil variables considered. Our results highlight the significant potential for AMF‐mediated mechanisms to promote SOC accumulation in agricultural soils, although this effect is context‐dependent. However, future research with different approaches and scales is needed to evaluate the impact of AMF on SOC dynamics in agricultural systems and elucidate the mechanisms behind their contribution to SOC accrual. Read the free Plain Language Summary for this article on the Journal blog.

Mycorrhizal fungus Rhizophagus irregularis mitigates symptoms of Verticillium wilt and enhances growth of olive trees (Olea europaea L.)

Mycorrhizal fungus Rhizophagus irregularis mitigates symptoms of Verticillium wilt and enhances growth of olive trees (Olea europaea L.)

Seasonal changes in the mycorrhizal symbiosis of Rhododendron tomentosum Harmaja in the Ukrainian Polissia

This study focuses on the mycorrhizal associations of Rhododendron tomentosum Harmaja with ericoid mycorrhizal fungi, typical for species in the Ericaceae family. The development of these symbiotic relationships varies seasonally and by habitat. Mycorrhizal colonization was studied across different phenological stages in natural populations of R. tomentosum in the Bilokorovytsky forestry, Zhytomyr region (Ukraine). Samples were taken at four stages of the growing season, analyzed morphologically, and quantitatively assessed. The results revealed that colonization peaks at the beginning and end of the vegetation period while declining during flowering and seed maturation. Additionally, we observed both ericoid mycorrhizae and dark septate endophytes (DSE) coexisting within the roots, suggesting that the symbiotic relationship is complex and influenced by multiple factors. These findings contribute to a deeper understanding of mycorrhizal dynamics in R. tomentosum and highlight the need for further research on seasonal and environmental influences on these associations.

Interaction between arbuscular mycorrhizal fungi and dark septate endophytes in the root systems of Populus euphratica and Haloxylon ammodendron under different drought conditions in Xinjiang, China

Background and AimsArbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) are known to enhance the tolerance of host plants to biotic and abiotic stresses, but the mechanism of their interaction under natural conditions has not been extensively studied.MethodsWe analyzed the endophytic fungal diversity and colonization characteristics in the typical desert plants Populus euphratica and Haloxylon ammodendron and the relationship between them and environmental factors.ResultsExcept for DSE in the roots of H. ammodendron, the colonization rates of AMF and DSE were significantly positively correlated with drought severity. The abundance of AMF and DSE under medium and mild drought conditions was greater than that under severe drought conditions. The root colonization rate and abundance of AMF were lower than those of DSE under the same drought conditions. The species diversity and abundance of AMF and DSE in P. euphratica were greater than those in H. ammodendron. AMF were more susceptible to soil factors such as soil water content, soil nitrogen and phosphorus content, and urease, whereas DSE were more affected by pH.ConclusionDrought stress has different effects on AMF and DSE in the roots of P. euphratica and H. ammodendron. DSE have a greater advantage in extremely arid environments. This study demonstrates the interaction between AMF and DSE with the host plants P. euphratica and H. ammodendron as well as their effects on the adaptation of host plants to the desert environment, which can provide a basis for strengthening desert vegetation management.

AM fungus plant colonization rather than an Epichloë endophyte attracts fall armyworm feeding.

Most cold-season grasses can be colonized by belowground arbuscular mycorrhizal (AM) fungi and foliar grass endophytes (Epichloë) simultaneously while also be attacked by insect herbivores. The colonization of AM fungi or the presence of grass endophytes is associated with increased resistance by the host plant. However, studies on how these two symbionts affect host plants and mitigate insect pest attack are currently lacking. In a glasshouse study we investigated the effects of an AM fungus (Acaulospora delicata), a foliar grass endophyte (Epichloë), and the insect pest Spodoptera frugiperda (fall armyworm, FAW) on plant growth, defense enzyme activity, and hormone concentrations of the important pasture grass Lolium perenne. Additionally, we assessed the selective behavior of FAW larvae in response to these interactions using olfactometer tests. Our results showed that the AM fungus and its co-colonization with Epichloë endophytes increased aboveground biomass, while Epichloë endophytes alone had no significant impact on ryegrass aboveground biomass. In contrast, FAW reduced aboveground biomass. The Epichloë endophytes and FAW significantly decreased the mycorrhizal colonization rate by 21.67% and 30.16%, respectively. Interestingly, compared to non-mycorrhizal plants, AM fungus colonized plants were more attractive to FAW larvae feeding, and the defense enzyme activity was not discernibly affected by any experimental treatments. The interactions of the AM fungus and Epichloë endophyte increased the jasmonic acid concentrations by 24.29% and decreased trasylol activity by 11.75% in the host plants under FAW attack. Neither the AM fungus nor Epichloë endophyte influenced the relative growth rate (RGR) of FAW. Overall, the AM fungus had a greater positive effect on plant growth than the Epichloë endophyte, regardless of FAW larvae infestation.

Ecological filters shape arbuscular mycorrhizal fungal communities in the rhizosphere of secondary vegetation species in a temperate forest.

The community assembly of arbuscular mycorrhizal fungi (AMF) in the rhizosphere results from the recruitment and selection of different AMF species with different functional traits. The aim of this study was to analyze the relationship between biotic and abiotic factors and the AMF community assembly in the rhizosphere of four secondary vegetation (SV) plant species in a temperate forest. We selected four sites at two altitudes, and we marked five individuals per plant species at each site. Soil rhizosphere samples were collected from each SV plant species, during the rainy and dry seasons. Soil samples from the rhizosphere of each plant species were analyzed for AMF spores, organic matter (OM), pH, soil moisture, and available phosphorus, and nitrogen. Three ecological filters influenced the AMF community assembly: host plant identity, abiotic factors, and AMF species co-occurrence. This assembly consisted of 61 AMF species, with different β-diversity values among plant species across seasons and altitudes. Canonical correspondence analysis revealed that AMF community composition is linked to OM and available P and N, with only a few AMF species co-occurring, while most do not. Our study highlights how ecological filters shape AMF structure, which is essential for understanding how soil and environmental factors affect AMF in SV plant species across seasons and altitudes.

The assembly of plant communities in relation to overlap in mycorrhizal and pathogenic root fungi

Abstract Plant species commonly associate with symbiotic arbuscular mycorrhizal (AM) and pathogenic root fungi, with many plants overlapping in their fungal community compositions. Overlap in AM fungi could promote coexistence by favouring competitively inferior or rare plants, or through the establishment of common mycorrhizal networks. Coexistence could also, however, be impeded if shared AM fungi disproportionately benefit competitively superior or abundant plant species. Overlap in pathogenic root fungi among closely growing plant species should increase the likelihood that an uninfected plant becomes infected, leading to reduced coexistence. Using vegetation plot data from an old‐field plant community along with high‐throughput sequence data on AM and pathogenic root fungal associations, we conducted three specific evaluations. First, we used null models to determine whether estimated overlap in AM or pathogenic root fungi among coexisting plant species was higher or lower than expected by chance. Second, we assessed whether estimated overlap in AM and pathogenic fungi differed between positively co‐occurring and negatively co‐occurring plant species. Third, we examined whether variation in plot‐level plant species richness was explained by the degree of estimated overlap in AM and pathogenic root fungi among those species. We found no evidence that estimated overlap in AM or pathogenic root fungal communities was higher or lower than expected under our null model. Additionally, positively and negatively co‐occurring pairs of plant species did not differ in their estimated overlap in either group of fungi. However, plant species richness was significantly higher in plots where plants were estimated to overlap more in AM fungi and significantly lower in plots where plant species were estimated to overlap more in pathogenic root fungi. Our results suggest that overlap in root fungal associations among plant species appears to be predictive of plant species richness, and therefore the assembly of plant communities. Read the free Plain Language Summary for this article on the Journal blog.

Insights and applications of Arbuscular mycorrhizal fungi

In natural ecosystems, rhizospheric soils are teeming with diverse biological organisms that enhance plant growth, nutrient absorption, stress tolerance and disease prevention. Among these organisms, arbuscular mycorrhizal (AM) fungi are particularly significant due to their symbiotic relationships with plants. Their application extends beyond natural ecosystems into agricultural and horticultural practices, where they contribute to improved soil health and plant productivity. This review discusses the benefits of incorporating AM fungi into modern agricultural systems to improve nutrient uptake, soil structure and plant resilience. It emphasizes the need for strategies to restore and maximize AM fungi's efficacy, ensuring sustainability and productivity in agriculture, industry and natural ecosystems.