Arbuscular Mycorrhizal Fungi Symbiosis Research Articles

Effects of arbuscular mycorrhizal fungi in the rhizosphere of two olive (Olea europaea) varieties Arbequina and Barnea under water deficit conditions.

One strategy to improve olive (Olea europaea ) tree drought tolerance is through the symbiosis of arbuscular mycorrhizal fungi (AMF), which helps alleviate water deficit through a combination of morphophysiological effects. Cuttings of olive varieties Arbequina (A) and Barnea (B) were grown with (+AMF) or without (-AMF) inoculum in the olive grove rhizosphere soil. One year after establishment, pots were exposed to four different water regimes: (1) control (100% of crop evapotranspiration); (2) short-period drought (20days); (3) long-period drought (25days); and (4) rewatering (R). To evaluate the influence of AMF on tolerance to water stress, stem water potential, stomatal conductance and the biomarkers for water deficit malondialdehyde, proline, soluble sugars, phenols, and flavonoids were evaluated at the end of the irrigation regimes. Stem water potential showed higher values in A(+) and B(+) in all water conditions, and the opposite was true for stomatal conductance. For proline and soluble sugars, the stem water potential trend is repeated with some exceptions. AMF inoculum spore communities from A(+ and -) and B(+ and -) were characterised at the morphospecies level in terms of richness and abundance. Certain morphospecies were identified as potential drought indicators. These results highlight that the benefits of symbiotic relationships between olive and native AMF can help to mitigate the effects of abiotic stress in soils affected by drought.

Arbuscular Mycorrhizal Fungi as Biostimulant and Biocontrol Agents: A Review

Arbuscular mycorrhizal fungi (AMF) are soil microorganisms living in symbiosis with most terrestrial plants. They are known to improve plant tolerance to numerous abiotic and biotic stresses through the systemic induction of resistance mechanisms. With the aim of developing more sustainable agriculture, reducing the use of chemical inputs is becoming a major concern. After providing an overview on AMF history, phylogeny, development cycle and symbiosis benefits, the current review aims to explore the potential of AMF as biostimulants and/or biocontrol agents. Nowadays, AMF inoculums are already increasingly used as biostimulants, improving mineral nutrient plant acquisition. However, their role as a promising tool in the biocontrol market, as an alternative to chemical phytosanitary products, is underexplored and underdiscussed. Thus, in the current review, we will address the mechanisms of mycorrhized plant resistance to biotic stresses induced by AMF, and highlight the various factors in favor of inoculum application, but also the challenges that remain to be overcome.

Sodium nitroprusside, a donor of nitric oxide, enhances arbuscular mycorrhizal fungi symbiosis with corn plant and mitigates Cd bioavailability in the rhizosphere

Arbuscular mycorrhizal fungi (AMF) have been demonstrated to influence the bioavailability of heavy metals (HM) in the rhizosphere and their absorption by plants. Nitric oxide (NO) has been shown to increase plant tolerance to environmental stresses and promote the plant-fungal symbiotic relationship. However, to date, no research has been conducted to investigate the impact of utilizing living organisms with specific molecules that are effective in promoting plant growth in conjunction with the chemical alterations of HM in the rhizosphere. Therefore, this study was conducted as a completely randomized factorial design using the rhizobox technique to investigate whether the use of Funneliformis mosseae fungi and sodium nitroprusside (SNP, 100 mM) as a donor of NO, alone or in combination, can improve corn plant growth and affect the Cd fractions in the rhizosphere of Cd-contaminated soil. The results show that the inoculation of AMF and the application of SNP, either alone or in combination, significantly increased plant growth. This was achieved by reducing the bioavailable form of Cd in the rhizosphere, which in turn led to a decrease in the concentration of Cd in corn plant tissues. The inoculation of AMF, either alone or in combination with SNP, resulted in a decrease in the concentration of Cd in its exchangeable (EXCH), carbonate-bound (CAR), and Fe–Mn oxides-bound (MnOX and FeOX) forms, and an increase in its organic matter-bound (ORG) and residual (RES) forms in the rhizosphere. The study found that the rhizosphere had lower concentration of bioavailable form of Cd (EXCH-Cd (43%), CAR-Cd (9%), MnOX-CD (18%), FeOX-Cd (33%) and ORG-Cd (30%)) and higher concentration of low-toxic form of Cd (RES-Cd (56%)). This indicates the role of root exudates in the redistribution of Cd fractions in soil. The study also revealed that AMF colonization, in combination with SNP, affected the biogeochemical fractions of Cd and reduced Cd mobility in the rhizosphere. This improvement in Cd mobility led to reduced Cd accumulation in the plant tissues, resulting in improved corn plant growth.

AMF symbiosis drives the rhizosphere microbiome to synergistically improve herbage growth in saline–alkaline soils

AbstractPlant–microbe interactions are essential in shaping plant performance and overall ecosystem functioning. However, the regulatory mechanisms underlying plant–microbe interactions mediated by mycorrhizal symbiosis in saline–alkaline soils are still not fully understood. Here, we aimed to clarify the synergistic regulatory mechanism through which arbuscular mycorrhizal fungi (AMF) symbiosis drives the rhizosphere microbiome to improve perennial herbage growth in saline–alkaline soils and evaluate phytoremediation efficiency. This study revealed that Funneliformis mosseae inoculation (i) strongly promoted the growth of all three herbage species (with values ranging from 21.62% to 233.33%), Na+ accumulation in plants (with values ranging from 24.63% to 188.89%), and decreased soil electrical conductivity (with values ranging from 7.68% to 12.87%), potentially suggesting improved phytoremediation efficiency with AMF symbiosis; (ii) increased nutritional content and decreased C:P and N:P ratios (with values ranging from 27.20% to 92.87%) and improved K+/Na+ and P/Na+ ratios (with values ranging from 2.60% to 302.96%); (iii) increased the abundance of some beneficial bacterial taxa and strengthened the significant strong relationships among most of these bacteria and plant biomass, ion homeostasis as well as stoichiometric ratio constants, and AMF inoculation treatments also consisted the higher proportion of differential genera significantly correlated with these plant factors as well as plant nutrient contents, potentially reflecting that AMF mediated the enrichment process of beneficial bacterial taxa and may strength functional interaction between plant and bacterial taxa, which may be importance for the enhancement of saline–alkaline tolerance of plants; and (iv) enhanced stability of the rhizosphere bacterial community and complexity of interaction networks, and the related indictors also established significant correlations with plant/soil factors, suggesting that the improvement of stability and functional complexity driven by AMF may also be beneficial for enhancing phytoremediation efficiency. These findings indicate that AMF inoculation plays its own beneficial role by simultaneously activating the potential of beneficial rhizosphere bacterial taxa and that their synergistic interaction is more beneficial for enhancing plant growth in salt‐affected soils and enhancing phytoremediation efficiency. This study helps to elucidate the underlying mechanisms through which AMF‐mediated rhizosphere bacterial community improve plant growth and tolerance to saline–alkaline stresses, and provides evidence that effective ecological restoration of saline–alkaline degraded grasslands can be achieved via the use of mycorrhizal symbiosis herbage.

Genome-Wide Identification and Characterization of the PHT1 Gene Family and Its Response to Mycorrhizal Symbiosis in Salvia miltiorrhiza under Phosphate Stress.

Phosphorus (P) is a vital nutrient element that is essential for plant growth and development, and arbuscular mycorrhizal fungi (AMF) can significantly enhance P absorption. The phosphate transporter protein 1 (PHT1) family mediates the uptake of P in plants. However, the PHT1 gene has not yet been characterized in Salvia miltiorrhiza. In this study, to gain insight into the functional divergence of PHT1 genes, nine SmPHT1 genes were identified in the S. miltiorrhiza genome database via bioinformatics tools. Phylogenetic analysis revealed that the PHT1 proteins of S. miltiorrhiza, Arabidopsis thaliana, and Oryza sativa could be divided into three groups. PHT1 in the same clade has a similar gene structure and motif, suggesting that the features of each clade are relatively conserved. Further tissue expression analysis revealed that SmPHT1 was expressed mainly in the roots and stems. In addition, phenotypic changes, P content, and PHT1 gene expression were analyzed in S. miltiorrhiza plants inoculated with AMF under different P conditions (0 mM, 0.1 mM, and 10 mM). P stress and AMF significantly affected the growth and P accumulation of S. miltiorrhiza. SmPHT1;6 was strongly expressed in the roots colonized by AMF, implying that SmPHT1;6 was a specific AMF-inducible PHT1. Taken together, these results provide new insights into the functional divergence and genetic redundancy of the PHT1 genes in response to P stress and AMF symbiosis in S. miltiorrhiza.

Arbuscular mycorrhiza and rhizosphere soil enzymatic activities as modulated by grazing intensity and plant species identity in a semi-arid grassland

Understanding the symbiosis of arbuscular mycorrhizal fungi (AMF) with plants in relation to soil nutrients and enzyme activities under different grazing intensities can be an important guide for the management and protection of semi-arid grasslands. The aim of the present study was to evaluate how the interaction of grazing intensity and plants shapes the composition of AMF communities and enzyme activities in a semi-arid grassland ecosystem in Iran. Sampling focused three dominant plant species (i.e., Salsola laricina, Artemisia siberia, and Stipa hohenackeriana) at sites with different grazing intensities. Soil chemical properties, enzyme activities, root colonization by AMF and AMF communities in the roots were evaluated. Potassium and nitrogen, as well as alkaline phosphatase and urease enzymatic activities were significantly increased at the heavily grazed site, whereas root colonization by AMF was reduced by the high grazing intensity. In addition, AM fungal root colonization is dependent on the host plant species and easier to measure as a sensitive indicator of sustainable grazing. Neither plant species nor grazing intensity affected AM fungal diversity in roots, which could be due to the overall low phylogenetic diversity of AMF in the grassland and the lack of significant differences in soil humidity, pH and organic carbon between the sites. However, plant species and soil properties were the two factors explaining variation in AMF community composition, while grazing had no significant effect. Therefore, AMF communities in root of the semi-arid grassland plants responded largely to plant type rather than to grazing intensity.

Aquaporin ZmTIP2;3 Promotes Drought Resistance of Maize through Symbiosis with Arbuscular Mycorrhizal Fungi.

Arbuscular mycorrhizal fungi symbiosis plays important roles in enhancing plant tolerance to biotic and abiotic stresses. Aquaporins have also been linked to improved drought tolerance in plants and the regulation of water transport. However, the mechanisms that underlie this association remain to be further explored. In this study, we found that arbuscular mycorrhiza fungi symbiosis could induce the gene expression of the aquaporin ZmTIP2;3 in maize roots. Moreover, compared with the wild-type plants, the maize zmtip2;3 mutant also showed a lower total biomass, colonization rate, relative water content, and POD and SOD activities after arbuscular mycorrhiza fungi symbiosis under drought stress. qRT-PCR assays revealed reduced expression levels of stress genes including LEA3, P5CS4, and NECD1 in the maize zmtip2;3 mutant. Taken together, these data suggest that ZmTIP2;3 plays an important role in promoting maize tolerance to drought stress during arbuscular mycorrhiza fungi symbiosis.

Investigating the simultaneous effect of chitosan and arbuscular mycorrhizal fungi on growth, phenolic compounds, PAL enzyme activity and lipid peroxidation in Salvia nemorosa L.

Considering the importance of Salvia nemorosa L. in the pharmaceutical and food industries, and also beneficial approaches of arbuscular mycorrhizal fungi (AMF) symbiosis and the use of bioelicitors such as chitosan to improve secondary metabolites, the aim of this study was to evaluate the performance of chitosan on the symbiosis of AMF and the effect of both on the biochemical and phytochemical performance of this plant and finally introduced the best treatment. Two factors were considered for the factorial experiment: AMF with four levels (non-inoculated plants, Funneliformis mosseae, Rhizophagus intraradices and the combination of both), and chitosan with six levels (0, 50, 100, 200, 400 mg L−1 and 1% acetic acid). Four months after treatments, the aerial part and root length, the levels of lipid peroxidation, H2O2, phenylalanine ammonia lyase (PAL) activity, total phenol and flavonoid contents and the main secondary metabolites (rosmarinic acid and quercetin) in the leaves and roots were determined. The flowering stage was observed in R. intraradices treatments and the highest percentage of colonization (78.87%) was observed in the treatment of F. mosseae × 400 mg L−1 chitosan. Furthermore, simultaneous application of chitosan and AMF were more effective than their separate application to induce phenolic compounds accumulation, PAL activity and reduce oxidative compounds. The cluster and principal component analysis based on the measured variables indicated that the treatments could be classified into three clusters. It seems that different treatments in different tissues have different effects. However, in an overview, it can be concluded that 400 mg L−1 chitosan and F. mosseae × R. intraradices showed better results in single and simultaneous applications. The results of this research can be considered in the optimization of this medicinal plant under normal conditions and experiments related to abiotic stresses in the future.

Transcriptome Analysis Reveals the Impact of Arbuscular Mycorrhizal Symbiosis on Toona ciliata var. pubescens Seedlings

Toona ciliata var. pubescens, known as “Chinese mahogany”, has high commercial value and is classified as a level II priority protected wild plant in China. However, due to overexploitation and its poor natural regeneration capacity, natural T. ciliata var. pubescens forests show varying degrees of decline in habitat adaptability. Arbuscular mycorrhizal fungi (AMF) symbiosis presents a potential strategy to enhance its regeneration. In this study, T. ciliata var. pubescens seedlings were inoculated with Septoglomus viscosum, followed by RNA-Seq analysis to compare gene expression differences between AMF-inoculated (AMI) and non-mycorrhizal (NM) treatments three months post-inoculation. A total of 16,163 differentially expressed genes (DEGs) were upregulated by AMF colonization, constituting 96.46% of the total DEGs. Specifically, 14,420 DEGs were exclusively expressed in the AMI treatment, while 35 DEGs were completely silenced. Most of the upregulated DEGs were located on the cell membrane, nucleus, and cytoskeleton and functioned in protein binding, S-adenosylmethionine-dependent methyltransferase activity, and lipid binding during cellular/macromolecule/protein localization, intracellular/protein transport, the cell cycle, and signal transduction. Additionally, lots of key genes related to oxidative stress responses, nutrient transport, and small GTPase-mediated signal transduction were found to be upregulated. These results suggest that AMF inoculation may enhance root cell growth by activating genes involved in nutrient uptake, stress responses, signal transduction, and substance transportation. This study elucidates the molecular mechanisms underlying the growth promotion of T. ciliata var. pubescens through AMF symbiosis, laying a foundation for the future application of AMF in its natural forest regeneration.

Defoliation modifies the response of arbuscular mycorrhizal fungi to drought in temperate grassland

Arbuscular mycorrhizal (AM) fungi predominate in grasslands, where they play a key role in enhancing plant water uptake and plant tolerance to drought. However, how plant defoliation, which is common to grazed and cut grasslands, modifies plant and AM fungi responses to drought remains unknown. Here, we examined how defoliation intensity modified plant and AM fungi responses to drought.This was done using an in situ factorial field experiment at Colt Park meadows, northern England, whereby mixed grassland communities were subjected to different intensities of defoliation in combination with simulated summer drought. We measured a range of plant, AM fungal, and soil microbial and chemical responses to defoliation and drought, both individually and in combination, and extracted neutral lipid fatty acid (NLFA) as an indicator of AM fungi energy storage status.High intensity defoliation significantly reduced root colonization by AM fungi, and the negative impact of drought on AM fungi extraradical hyphal length was amplified under high intensity defoliation. Drought had no effect on total shoot biomass but reduced specific root length and increased soil NLFA concentrations, indicating an increase in AM fungi energy reserves. However, defoliation dampened this response, implying that defoliation suppresses AM fungi energy reserves under drought.Our findings suggest that plant communities can maintain above-ground productivity under drought with the assistance of AM fungi symbiosis, but that defoliation suppresses positive plant-fungi interactions under drought. Taken together, our findings provide new insights into how drought and defoliation, a key feature of grassland management, combine to negatively impact the plant-AM fungi associations in grassland.

Root-mycorrhizae species and variety pairing matters: A study case with arbuscular mycorrhizal fungi communities and Vitis vinifera varieties in the southern Brazil

Vitis vinifera varieties can change the arbuscular mycorrhizal fungi (AMF) community structure in their rhizosphere. Our aim here was to present a quantitative analysis of the AMF species associated with V. vinifera varieties from Cabernet, Merlot, and Sauvignon groups in a subtropical Cambisol, Southern Brazil. Eight V. vinifera varieties were selected for the field experiment from September 2019 to June 2021. For each studied variety, we established five rectangular plots (60.0 × 14.0 m) using a randomized block design with seven blocks. We found seven main groups considering the dissimilarities of AMF spores: i) Entrophospora claroidea in the root zone of C. Eidos and C. Volos (both varieties from the Cabernet group); ii) Funneliformis mosseae in the root zone of Fleurtai; iii) Racocetra coralloidea in the root zone of Merlot Khantus; iv) Scutellospora calospora in the root zone of M. Khorus; v) Quatunica erytrophus in the root zone of Sauvignon Kretos; vi) Glomus coremioides in the root zone of S. Rytos; and vii) Acaulospora tuberculata in the root zone of Soreli. The results of our study highlighted the importance of considering V. vinifera varieties as potential hosts for specific AMF species by creating an AMF-host pairing specificity to improve root colonisation and plant yield in their own advantage. Thus, field experiments considering V. vinifera varieties into agrosystems for vine production contribute to our understanding of the AMF symbiosis in subtropical soils.

Effectiveness of inoculation types and dosages of arbuscular mycorrhizal fungi (AMF) on the growth of perintis chili variety (Capsisum annum L.) on entisol soil

This research aims to optimize the growth of a variety chili plants, so called perintis, as Aceh’s superior local chili variety, most of which are cultivated on entisol soil types. Entisol soil has low nutrient content and bound P elements which are difficult for plant roots to absorb. In this case, the symbiosis of arbuscular mycorrhizal fungi (AMF) with the roots of chili plants is attempted. This research used a 3x3 factorial randomized block design with factors including the type and dose of mycorrhiza. The results showed that the use of arbuscular mycorrhizal fungi (FMA) type Gigaspora sp at a dose of 10 g−1 plant showed a significant interaction on chili plant height 35 DAP, while mixed mycorrhizal types between Glomus mosseae and Gigaspora sp at a dose of 10 g−1 show significant interaction on chili plant height 50 HST. The mycorrhizal type Glomus mosseae was the best in terms of colonizing the roots of perintis variants of chili plants.

Effects of Funneliformis mosseae on Growth and Photosynthetic Characteristics of Camellia oleifera under Different Nitrogen Forms

Nitrogen fertilizer increases agricultural yields but increases economic costs and causes a series of environmental problems. Arbuscular mycorrhizal fungi (AMF) have the potential to be used as biological fertilizer. However, the influence of nitrogen form on plant growth responsiveness to AMF inoculation is poorly understood. In this study, we investigated the effects of Funneliformis mosseae on growth, root morphology and photosynthetic characteristics of Camellia oleifera under different nitrogen forms during three harvest periods and clarified the most suitable nitrogen form for C. oleifera–AMF symbiosis. The results showed that urea, ammonium and nitrate nitrogen promoted plant growth and photosynthetic capacity, among which urea treatment had the highest value in all three harvests. No significant difference in plant growth parameters was observed between ammonium and nitrate nitrogen treatments in the first two harvests, while the plant height was significantly lower under ammonium nitrogen treatment than nitrate nitrogen treatment in the third harvest. Inoculation with F. mosseae in the presence of indigenous AMF could promote AMF colonization and plant growth at all three harvest times. Inoculation with F. mosseae significantly increased gas exchange parameters, the maximum photochemical efficiency (Fv/Fm) and the actual photochemical efficiency (ΦPSII). Inoculation with AMF increased the photochemical quenching coefficient (qP) better under urea treatment and improved the non-photochemical quenching coefficient (qN) better under ammonium nitrogen treatment. Principal component analysis showed that urea is the most beneficial nitrogen fertilizer for C. oleifera–AMF symbiosis. The results of this study provide a theoretical basis for the combination use of AMF and nitrogen fertilizer in agroforestry.

The role of arbuscular mycorrhizal symbiosis in plant abiotic stress.

Arbuscular mycorrhizal fungi (AMF) can penetrate plant root cortical cells, establish a symbiosis with most land plant species, and form branched structures (known as arbuscules) for nutrient exchange. Plants have evolved a complete plant-AMF symbiosis system to sustain their growth and development under various types of abiotic stress. Here, we highlight recent studies of AM symbiosis and the regulation of symbiosis process. The roles of mycorrhizal symbiosis and host plant interactions in enhancing drought resistance, increasing mineral nutrient uptake, regulating hormone synthesis, improving salt resistance, and alleviating heavy metal stress were also discussed. Overall, studies of AM symbiosis and a variety of abiotic stresses will aid applications of AMF in sustainable agriculture and can improve plant production and environmental safety.

The influence of a soil amendment on the abundance and interaction of arbuscular mycorrhizal fungi with arable soils and host winter wheat.

Arbuscular mycorrhizal (AM) fungi have been shown to be associated with an estimated 70 % of vascular terrestrial plants. Such relationships have been shown to be sensitive to soil disturbance, for example, tillage in the preparation of a seed bed. From the application of arable soil management, AM fungal populations have been shown to be negatively impacted in abundance and diversity, reducing plant growth and development. The present study aims to utilise two sources (multipurpose compost and a commercial inocula) of mycorrhizal fungi for the amendment of arable soils supporting Zulu winter wheat under controlled conditions and quantify plant growth responses. A total of nine fields across three participating farms were sampled, each farm practicing either conventional, reduced, or zero tillage soil management exclusively. Soil textures were assessed for each sampled soil. Via the employment of AM fungal symbiosis quantification methods, AM fungi were compared between soil amendments and their effects on crop growth and development. The present study was able to quantify a mean 6 cm increase to crop height (P<0.001), 10 cm reduction to root length corresponding with a 2.45-fold increase in AM fungal arbuscular structures (P<0.001), a 1.15-fold increase in soil glomalin concentration corresponding to a 1.26-fold increase in soil carbon, and a 1.32-fold increase in the relative abundance of molecular identified AM fungal sequences for compost amended soils compared to control samples. Mycorrhizal inocula, however, saw no change to crop height or root length, AM fungal arbuscules were reduced by 1.43-fold, soil glomalin was additionally reduced by 1.55-fold corresponding to a reduction in soil carbon by 1.31-fold, and a reduction to relative AM fungal species abundance by 1.26-fold. The present study can conclude the addition of compost as an arable soil amendment is more beneficial for the restoration of AM fungi beneficial to wheat production and soil carbon compared to the addition of a commercial mycorrhizal inocula.

The Effect of Pruning and Growing Media Composition on Arbuscular Mycorrhizal Propagation

The symbiosis of arbuscular mycorrhizal fungi with plants is the oldest symbiosis in the world. The obligate nature of mycorrhizal fungi in symbiotic relationships is believed to underlie its enduring presence to this day. The application of arbuscular mycorrhizal fungi (AMF) based fertilizers has become increasingly common. Spores are the most important organs that determine the quality of AMF-based fertilizers, along with AMF colonization in the roots. The production of AMF spores is greatly influenced by plant physiology, including photosynthesis processes affected by canopy abundance, as well as the type of planting medium, which determines plant root growth and AMF habitat. This study was conducted to investigate the effect of pruning and planting medium composition on AMF infection and spore production in AMF propagation using sorghum as the host plant. The pruning levels tested were at one, two, and three months after germination, and thereafter, each plant was maintained for 136 days after planting (DAP). The tested planting medium composition was the ratio between zeolite and compost in five different compositions: (v/v) 1) 100:0, 2) 90:10, 3) 70:30, and 4) 50:50. The chemical characteristic of compost used was contained 15.5% C, 1.49% N, 2.54% P2O5, 1.49% K2O, pH 6.6, and some microelements such as Cr, Fe, Zn, and Mn at 5.2 ppm, 5961 ppm, 294 ppm, and 199 ppm, respectively. The Sukabumi‘s zeolite used had a size of 2-3 mm. Propagation of AM fungal spores was carried out using polybags containing 10 kg of medium according to the treatment. Plant maintenance was carried out by alternating between watering with water and Johnson nutrient solution. Watering was performed until the plants were 120 days old, and subsequently, no watering was done until 136 days after planting. The observed parameters were the development of AMF spore numbers until a 4.5-month incubation period. The results showed that pruning time can affect spore production if the plant has reached a certain vegetative age, which is three months for sorghum. Additionally, adding 10% compost to zeolite medium can enhance spore formation, even though sorghum growth may not be at its maximum in this medium composition.

Arbuscular mycorrhizal fungi can reduce severity of fusariosis (Fusarium oxysporum) in cowpea plants (Vigna unguiculata (L.) Walp.)

Mycorrhizal symbiosis with arbuscular mycorrhizal fungi (AMF) provides plants with high nutrient absorption and non-nutritional benefits such as resistance to diseases. Fusariosis (Fusarium oxysporum) affects cowpea (Vigna unguiculata (L.) Walp.) production, which is a common culture in household farms in the northeast region of Brazil. The aim of this study was to evaluate the potential of native AMF from Maranhão Cerrado to provide resistance/non-nutritional benefits to cowpea plants infected with F. oxysporum f.sp. tracheiphilum. The bioassay was conducted using cowpea plants to assess their responses to different AMF species and F. oxysporum under controlled greenhouse conditions. Vegetative development of cowpeas (fresh and dry shoot and root mass, leaf number, and plant height) benefited from AMF symbiosis, especially with Claroideoglomus etunicatum and Acaulospora morrowiae. All AMF species reduced the severity score of the disease, confirming the potential use of mycorrhizal fungi species to reduce F. oxysporum damage in cowpea cultures.

Exploring the Roles of Arbuscular Mycorrhizal Fungi in Plant–Iron Homeostasis

Arbuscular mycorrhizal fungi (AMF) form a vital symbiotic relationship with plants. Through their extensive hyphal networks, AMF extend the absorptive capacity of plant roots, thereby allowing plants to reach otherwise inaccessible micronutrient sources. Iron, a critical micronutrient involved in photosynthesis and other metabolic processes, often becomes inaccessible owing to its tendency to form insoluble complexes in soil. AMF symbiosis significantly ameliorates this challenge by enhancing iron uptake and homeostasis in plants, altering root architecture, and producing root exudates that improve iron solubility. Moreover, the interaction with diverse soil bacteria, particularly plant growth-promoting rhizobacteria, can potentiate the benefits of AMF symbiosis. Siderophores are low-molecular-weight chelators with iron-binding capacities produced by various microorganisms and plant roots. They play pivotal roles in regulating intracellular iron and have been identified in different mycorrhizal associations, including AMF. While molecular mechanisms behind AMF-mediated iron uptake have been partially explored, the intricate networks involving AMF, plants, siderophores, and other soil microbiota are largely unknown. This review focuses on the multifaceted roles of AMF in plant–iron homeostasis, interactions with soil bacteria, and the potential of siderophores in these processes, emphasizing the possibilities for harnessing these relationships for sustainable agriculture and enhancing plant productivity.

Rhizosphere interface microbiome reassembly by arbuscular mycorrhizal fungi weakens cadmium migration dynamics.

The prevalence of cadmium (Cd)-polluted agricultural soils is increasing globally, and arbuscular mycorrhizal fungi (AMF) can reduce the absorption of heavy metals by plants and improve mineral nutrition. However, the immobilization of the rhizosphere on cadmium is often overlooked. In this study, Glomus mosseae and Medicago sativa were established as symbiotes, and Cd migration and environmental properties in the rhizosphere were analyzed. AMF reduced Cd migration, and Cd2+ changed to an organic-bound state. AMF symbiosis treatment and Cd exposure resulted in microbial community variation, exhibiting a distinct deterministic process (|βNTI| > 2), which ultimately resulted in a core microbiome function of heavy metal resistance and nutrient cycling. AMF increased available N and P, extracellular enzyme activity(LaC, LiP, and CAT), organic matter content (TOC, EOC, and GRSP), and Eh of the rhizosphere soil, significantly correlating with decreased Cd migration (p < 0.05). Furthermore, AMF significantly affected root metabolism by upregulating 739 metabolites, with flavonoids being the main factor causing microbiome variation. The structural equation modeland variance partial analysisrevealed that the superposition of the root metabolites, microbial, and soil exhibited the maximum explanation rate for Cd migration reduction (42.4%), and the microbial model had the highest single explanation rate (15.5%). Thus, the AMF in the rhizosphere microenvironment can regulate metabolite-soil-microbial interactions, reducing Cd migration. In summary, the study provides a new scientific explanation for how AMF improves plant Cd tolerance and offers a sustainable solution that could benefit both the environment and human health.

Revealing the effects and mechanisms of arbuscular mycorrhizal fungi on manganese uptake and detoxification in Rhus chinensis

Arbuscular mycorrhizal fungi (AMF) can alleviate heavy metal phytotoxicity and promote plant growth, while the underlying mechanisms of AMF symbiosis with host plants under manganese (Mn) stress remain elusive. A pot experiment was carried out to investigate the plant growth, micro-structure, Mn accumulation, subcellular distribution, chemical forms, and physiological and biochemical response of Rhus chinensis inoculated with Funneliformis mosseae (FM) under different Mn treatments.The results showed that compared with plants without FM, FM-associated plants exhibited higher growth status, photosynthetic pigments, and photosynthesis under Mn stress. FM-associated plants were able to maintain greater integrity in mesophyll structure, higher thickness of leaf, upper epidermis, and lower epidermis under Mn treatment, and promote leaf growth. Mn accumulation in leaves (258.67–2230.50 mg kg−1), stems (132.67–1160.00 mg kg−1), and roots (360.92–2446.04 mg kg−1) of the seedlings inoculated with FM was higher than non-inoculated ones. FM-associated plants exhibited higher osmotic regulating substances and antioxidant enzymes’ activities under Mn exposure, suggesting lower Mn toxicity in FM inoculated seedlings, despite the augment in Mn accumulation. After FM inoculation, Mn concentration (151.04–1211.32 mg kg−1) and percentage (64.41–78.55%) enhanced in the cell wall, whilst the transport of Mn to aerial plant organs decreased. Furthermore, FM symbiosis favored the conversion of Mn from high toxic forms (2.17–15.68% in FEthanol, 11.37–24.52% in Fdeionized water) to inactive forms (28.30–38.15% in FNaCl, 18.07–28.59% in FHAc, 4.41–17.99% in FHCl) with low phytotoxicity. Our study offers a theoretical basis for remediation of the FM- R. chinensis symbiotic system in Mn-contaminated environments.