Mycorrhizal Plants Research Articles

Enhancing chickpea growth through arbuscular mycorrhizal fungus inoculation: facilitating nutrient uptake and shifting potential pathogenic fungal communities.

Arbuscular mycorrhizal fungi (AMF) are the most widespread plant symbionts associated with plant roots, and theyperform numerous functions that contribute to plants' health and physiology. However, there are many knowledge gaps in how the interactions between AMF and root mycobiomes influence the performance of the host plants. To this end, we inoculated a local chickpea cultivar grown in agricultural soil under semi-controlled conditions with Rhizophagus irregularis. In addition to examining mycorrhizal colonization, plant biomass, and mineral nutrition, we sequenced the ITS region of the rDNA to assess the chickpea mycobiome and identify key fungal taxa potentially responding to R. irregularis inoculation. Our results showed that inoculation had a positive effect on chickpea biomass and mineral nutrition, especially the total aboveground phosphorus, potassium and sodium contents. Fusarium, Sporomia, Alternaria, and unknown Pleosporales were the most abundant taxa in the roots, while Stachybotris, Penicillum, Fusarium, Ascobolus, an unknown Pleosporales and Acrophialophora were the most abundant in the rhizosphere. Among the ASVs that either were enriched or depleted in the rhizosphere and roots are potential plant pathogens from the genera Didymella, Fusarium, Neocosmospora, and Stagonosporopsis. This study highlights the relevance of AMF inoculation not only for enhancing chickpea growth and mineral nutrition in semi-arid conditions but also for influencing the composition of the plants' fungal community which contributes to improved plant performance and resilience against biotic and abiotic stress.

Arbuscular mycorrhizal fungi and plant growth-promoting rhizobacteria promoted changes in plant metabolism and the volatile profile of Piper callosum Ruiz & Pav

Piper callosum Ruiz & Pav. is known in the Amazon as a paregoric elixir and exists as a shrub native to the Neotropics. In traditional medicine, the tea from its leaves is used to treat pain in the digestive tract, rheumatism, and muscular aches. This study aimed to evaluate the influence of arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) inoculation on the secondary metabolism of P. callosum. The plants were inoculated after 30 days of cultivation and kept in a greenhouse. Plant development parameters were monitored at 30-, 60-, and 90-days after inoculation (DAI) and indicated that AMF and PGPR favored plant growth throughout all stages of development. The leaf volatiles extracted by simultaneous distillation and extraction were analyzed by gas chromatography coupled with mass spectrometry and showed that phenylpropanoids and monoterpene hydrocarbons were predominant in all essential oils, revealing distinct abundance patterns across the different sampling points. The major volatile compounds identified were safrole, methyl eugenol, and β-pinene, and a reduction trend in their content was observed for safrole and methyl eugenol, especially at 90 DAI in both treatments. Principal component analysis revealed that germacrene D-4-ol and limonene were among the most influential in both treatments. Finally, the total phenolic content and the enzymatic activity of phenylalanine ammonia-lyase revealed different effect patterns for inoculation and time of evaluation on each treatment. All the data presented indicate that symbiotic inoculation can optimize the production of essential oil, which can improve the quality and productivity of P. callosum plants.

Unveiling a Hidden Synergy: Empowering Biofertilizers for Enhanced Plant Growth With Silicon in Stressed Agriculture.

Food security is increasingly threatened by climate change and environmental pressures that hinder plant growth and development. Harnessing soil microorganisms, such as mycorrhizal fungi and plant growth-promoting bacteria, offers a promising approach to boost crop production. However, existing screening methods for these microorganisms often prove ineffective in real-world, stress-prone environments, limiting the efficacy of microbial biofertilizers. To address this challenge, this review proposes the integration of silicon-renowned for its stress-mitigating properties in plants-with biofertilizers. Silicon has been shown to work synergistically with plant growth-promoting microorganisms, enhancing plant resilience to environmental stress while improving colonization efficiency and plant-microbe interactions in stressful conditions. By combining silicon with biofertilizers to create silicon-enriched biofertilizers, this strategy has the potential to optimize microbial performance and fortify food security against global challenges. The review advocates for the co-application of silicon and microbial biofertilizers as a sustainable solution to boost plant resilience against environmental stressors, thereby contributing to agricultural sustainability.

Independent and differential effects of arbuscular mycorrhizal fungal composition and plant pathogens on plant traits and nitrogen uptake.

Arbuscular mycorrhizal fungi (AMF), as microbial mutualists, interact with various microbial taxa, including pathogens, and significantly shape the ecology and evolution of their host species. However, how AMF and pathogens jointly or independently affect plant traits and nitrogen uptake remains unclear. Here, we conducted a factorial experiment with three AMF treatments (AMF-free-control, Funneliformis mosseae, and a mixture of AMF species of F. mosseae and C. etunicatum), four plant-pathogen pairs, each under two pathogen treatments (one pathogen and a pathogen-free control). After 65 days of growth, we measured AMF colonization, pathogen infection, plant functional traits and ammonium and nitrate uptake. Our findings reveal that AMF and pathogens independently influence plant traits and nitrogen uptake, with no observed interactions between them. Specifically, colonization by F. mosseae or a mixed AMF species reduced nitrate uptake and plant height, without affecting root traits or ammonium uptake. In contrast, pathogen infection enhanced acquisitive root traits, such as increased specific root length and area but did not impact shoot traits or nitrogen uptake. These results broaden our understanding of the tripartite interactions among plants, AMF and pathogens, offering insights into how plant-microbial relationships influence plant health, growth and nitrogen cycling.

Role of bio-stimulants on the advancement of vegetable production: A review

Abstract. Since climate of the globe is changing abruptly, causing tremendous challenges (biotic and abiotic stresses) on the production of vegetable crops, it seems to be difficult to ensure the food security for the rapidly growing population of the world if sustainable production systems are adopted. Though farmers are indiscriminately applying inorganic fertilizers and plant protection chemicals to replenish the fertility of their fields and protect their plants from pests, the issue of sustainable production seems to have been forgotten. Thus, the use of organic factors of production is a must in order to overcome the challenges so that production of healthy products can be maintained in an eco-friendly manner through the utilization of Bio-stimulators. Bio-stimulants have a crucial role in enhancing the growth, development and overall performance of different vegetable crops belonging to different families; Solanaceae, Alliaceae, Amaranthaceae, and Brassicaceae. The most commonly utilized bio-stimulants in the field of agriculture worldwide are humic substances (humic acid and fulvic acid), plant or animal-based protein hydrolysates, macro and micro-algal extracts (seaweed extracts), silicon, arbuscular mycorrhizal fungi and plant growth-promoting rhizobacteria. Bio-stimulants have important role in enhancing the growth characteristics, yielding potential, biochemical compositions (concentrations of ascorbic acid, and carotenoid content) in tomato plants and in other plants belonging to Solanaceae family like eggplant. Application of different types of bio-stimulants results in the improvement of growth, yields and chlorophyll and allicin contents in the Alliaceae species (onion and garlic). In the vegetable crops belonging to the family of Amaranthaceae (Spinach and Amaranthus), bio-stimulants have important impacts in the improvement of seed germination, increasing of plant height, photosynthetic pigments, yield and nutritional composition. Increased plant growth, photosynthetic rate and stomatal conductance, yield parameters, phenolic and flavonoid compounds and seed fatty acid concentration are also the results of bio-stimulant applications in the brassica species (cabbage, broccoli, rapeseed, mustard). Thus, the sustainable agriculture systems could be guaranteed by using bio-stimulants to boost the production of vegetable crops both quantitatively and qualitatively.

Transcriptomic responses of Solanum tuberosum cv. Pirol to arbuscular mycorrhiza and potato virus Y (PVY) infection

Arbuscular mycorrhizal fungi (AMF) serve as both plant symbionts and allies in resisting pathogens and environmental stresses. Mycorrhizal colonization of plant roots can influence the outcomes of plant-pathogen interactions by enhancing specific host defense mechanisms. The transcriptional responses induced by AMF in virus-infected plants remain largely unexplored. In the presented study, we employed a comprehensive transcriptomic approach and qPCR to investigate the molecular determinants underlying the interaction between AMF and potato virus Y (PVY) in Solanum tuberosum L. Our primary goal was to identify the symbiosis- and defense-related determinants activated in mycorrhizal potatoes facing PVY. Through a comparative analysis of mRNA transcriptomes in experimental treatments comprising healthy and PVY-infected potatoes colonized by two AMF species, Rhizophagus regularis or Funneliformis mosseae, we unveiled the overexpression of genes associated with mycorrhiza, including nutrient exchange, lipid transfer, and cell wall remodeling. Furthermore, we identified several differentially expressed genes upregulated in all mycorrhizal treatments that encoded pathogenesis-related proteins involved in plant immune responses, thus verifying the bioprotective role of AMF. We investigated the relationship between mycorrhiza levels and PVY levels in potato leaves and roots. We found accumulation of the virus in the leaves of mycorrhizal plants, but our studies additionally showed a reduced PVY content in potato roots colonized by AMF, which has not been previously demonstrated. Furthermore, we observed that a virus-dependent reduction in nutrient exchange could occur in mycorrhizal roots in the presence of PVY. These findings provide an insights into the interplay between virus and AMF.

Stable isotope analysis indicates partial mycoheterotrophy in arbuscular mycorrhizal woody seedlings in tropical forests

Abstract Chlorophyllous plants exhibiting partial mycoheterotrophy obtain carbon through mycorrhizal interactions in addition to photosynthesis. In arbuscular mycorrhizal (AM) plants, the Paris‐morphotype (i.e. hyphal coils) is considered essential for mycoheterotrophic carbon gains. Numerous tree species in tropical lowland forests form this morphotype, and under light‐ and nutrient‐limitation, additional carbon gain would be beneficial. However, if seedlings of woody species in the understory of tropical lowland forests exhibit partial mycoheterotrophy remains unexplored. Here we (a) examined the AM morphotype (Paris‐ or Arum‐type) in seedlings of 41 tropical woody species, and (b) to determine if any of the target Paris‐type species are partially mycoheterotrophic, we compared their multi‐element stable isotope natural abundance (13C, 2H, 18O, 15N) with neighbouring autotrophic non‐Paris‐type reference seedlings. About 50% of the investigated species (and 80% of the genera) exhibited the Paris‐type, expanding the number of tropical plant genera with Paris‐type AM. Enrichment in 13C, but not in 18O in target compared with neighbouring reference plants indicated partial mycoheterotrophy in seedlings of 6 of the 21 investigated Paris‐type AM species. Our results indicate for the first time that carbon gain through mycoheterotrophy occurs in seedlings of AM tropical tree species. In tropical forests, partial mycoheterotrophy during seedling establishment may confer so far unrecognised ecological advantages influencing seedling recruitment and ecosystem dynamics. Read the free Plain Language Summary for this article on the Journal blog.

Synergistic effects of AMF and PGPR on improving saline-alkaline tolerance of Leymus chinensis by strengthening the link between rhizosphere metabolites and microbiomes

Arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) can synergistically enhance their promotional effects on plants. The positive effects are closely related to their modulation on rhizosphere microbiomes. Leymus chinensis is widely used in restoration of saline-alkaline grasslands. However, the information is unavailable on mechanisms of inoculating AMF and PGPR in enhancing saline-alkaline tolerance of L. chinensis. We conducted a pot experiment to examine effects of separate and combined inoculation of AMF and PGPR, with a focus on the pathways of AMF and PGPR effects by regulating complex interactions in plant rhizosphere. The combined inoculation significantly increased plant biomass (by 40.18–193.18 %) and Na+ accumulation, and decreased soil EC and pH to a greater extent than the separate inoculation did, and it was also superior in terms of multiple nutrient accumulation, root ion homeostasis ratios and soil enzyme activities. The combined inoculation significantly enriched beneficial bacterial and symbiotic mycorrhizal taxa, and increased complexity and stability of rhizosphere microbiome. Coexistence of AMF and PGPR activated beneficial secondary metabolic pathways and higher expression of beneficial metabolites, which regulates plant growth and stress response. The inoculation of AMF and PGPR synergically promoted interactions among keystone microbial species from different cluster modules and rhizosphere soil metabolites, and strengthened the roles of core microorganisms and core metabolites, and their interrelations and their relations with host plant. These results implies that the synergistic positive effects of AMF and PGPR on saline-alkaline tolerance of L. chinensis is realized by strengthening the links between rhizosphere metabolites and microbiomes.

Rhizophagus intraradices mediated mitigation of arsenic toxicity in wheat involves differential distribution of arsenic in subcellular fractions and modulated expression of Phts and ABCCs

Biomagnification of arsenic in food chain through wheat consumption poses a serious threat to human health. Therefore, it is necessary to elucidate mechanism of arsenic tolerance and detoxification in wheat. The study aimed to unravel the strategies adopted by arbuscular mycorrhizal fungi to alleviate arsenic toxicity in wheat. To accomplish this, independent and interactive effects of arsenic and Rhizophagus intraradices were assessed. Colonization by R. intraradices resulted in lower expression of high-affinity phosphate transporters (Phts) in comparison with non-mycorrhizal (NM) plants, thereby lowering arsenic concentrations in mycorrhizal (M) plants. Additionally, the subcellular fractionation analysis indicated differential distribution of arsenic. In NM plants, arsenic accumulated primarily in cell wall and organelle fractions. Conversely, in M plants arsenic was more concentrated in the cell wall and vacuolar fractions. This was related to higher levels of hydroxyl and aldehyde groups in cell wall fraction of root along with increased expression of C-type ATP-binding cassette transporters in root and leaves. These factors enabled effective sequestration of arsenic in the cell wall and vacuoles of M plants, thereby reducing its toxicity. Furthermore, the proportion of inorganic arsenic was lower in M plant, as it transformed it into less toxic organic forms.

Unveiling the hidden world: How arbuscular mycorrhizal fungi and its regulated core fungi modify the composition and metabolism of soybean rhizosphere microbiome

BackgroundThe symbiosis between arbuscular mycorrhizal fungi (AMF) and plants often stimulates plant growth, increases agricultural yield, reduces costs, thereby providing significant economic benefits. AMF can also benefit plants through affecting the rhizosphere microbial community, but the underlying mechanisms remain unclear. Using Rhizophagus intraradices as a model AMF species, we assessed how AMF influences the bacterial composition and functional diversity through 16 S rRNA gene sequencing and non-targeted metabolomics analysis in the rhizosphere of aluminum-sensitive soybean that were inoculated with pathogenic fungus Nigrospora oryzae and phosphorus-solubilizing fungus Talaromyces verruculosus in an acidic soil.ResultsThe inoculation of R. intraradices, N. oryzae and T. verruculosus didn’t have a significant influence on the levels of soil C, N, and P, or various plant characteristics such as seed weight, crude fat and protein content. However, their inoculation affected the structure, function and nutrient dynamics of the resident bacterial community. The co-inoculation of T. verruculosus and R. intraradices increased the relative abundance of Pseudomonas psychrotolerans, which was capable of N-fixing and was related to cry-for-help theory (plants signal for beneficial microbes when under stress), within the rhizosphere. R. intraradices increased the expression of metabolic pathways associated with the synthesis of unsaturated fatty acids, which was known to enhance plant resistance under adverse environmental conditions. The inoculation of N. oryzae stimulated the stress response inside the soil environment by enriching the polyene macrolide antifungal antibiotic-producing bacterial genus Streptomyces in the root endosphere and upregulating two antibacterial activity metabolic pathways associated with steroid biosynthesis pathways in the rhizosphere. Although inoculation of pathogenic fungus N. oryzae enriched Bradyrhizobium and increased soil urease activity, it had no significant effects on biomass and N content of soybean. Lastly, the host niches exhibited differences in the composition of the bacterial community, with most N-fixing bacteria accumulating in the endosphere and Rhizobium vallis only detected in the endosphere.ConclusionsOur findings demonstrate that intricate interactions between AMF, associated core fungi, and the soybean root-associated ecological niches co-mediate the regulation of soybean growth, the dynamics of rhizosphere soil nutrients, and the composition, function, and metabolisms of the root-associated microbiome in an acidic soil.

Impact of Poultry Manure-Derived Biochar and Bio-Fertilizer Application to Boost Production of Black Cumin Plants (Nigella sativa L.) Grown on Sandy Loam Soil

Biochar derived from poultry manure increases nutrient availability and promotes plant growth. This study investigated the effect of biochar with mycorrhizal and/or plant growth-promoting rhizobacteria on soil fertility, chemical properties, oil, and seed yield of Black Cumin (Nigella sativa L.) plants. A split-plot design with three replicates was employed, with biochar derived from poultry litter (BC) applied at rates of 0, 5, and 10 t ha−1, with beneficial microbes such as arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) affecting the growth of Black Cumin plants, and some soil properties, such as pH, electrical conductivity (EC), soil organic matter (SOM) and fertility index (FI), showing significant differences (p ≤ 0.05) among biochar and/or bio-fertilizer treatments. All biochar treatments with or without bio-fertilizers significantly increased pH, EC, OM and FI in comparison to the control treatment. The results demonstrated that applying biochar at the highest rate (10 t ha−1) increased fresh and dry capsule weights by 94.51% and 63.34%, respectively, compared to the control treatment (C). These values were significantly increased by 53.05 and 18.37%, compared to untreated plants when combined with AMF and PGPR. Furthermore, when biochar was applied in conjunction with both AMF and PGPR, fresh and dry capsule weights saw significant increases of 208.84% and 91.18%, respectively, compared to the untreated control treatment. The interaction between biochar, AMF, and PGPR significantly improved plant growth, yield, soil properties, and the fixed and volatile oil content of Black Cumin. These findings suggest that the combined application of biochar, AMF, and PGPR enhances nutrient availability and uptake, leading to improved growth and higher yields in Black Cumin plants, resulting in increased yield production.

Diversity of Mycorrhizal Types Along Altitudinal Gradients in the Tropical Andes

ABSTRACTAimMycorrhizal fungi play key roles in the functioning of terrestrial ecosystems. The main types of mycorrhizal associations are arbuscular mycorrhizae, ectomycorrhizae, ericoid mycorrhizae and orchid mycorrhizae. Previous studies have shown that the abundance of plants with different types of mycorrhizal associations change gradually along latitudinal and altitudinal gradients driven by the effects of climate and soil nutrients. We aimed to understand how altitude and climatic and soil variables shape the distribution patterns of tropical plant mycorrhizal types and nitrogen‐fixing plants along altitudinal gradients in the Andes.LocationColombian Andean mountain range.Time PeriodPresent day.Major Taxa StudiedPlants (vascular and non‐vascular).MethodsWe used a herbarium plant records database and assigned mycorrhizal type to each plant species based on the available literature. Bioclimatic and soil variables were also compiled at a resolution of 10 km. We calculated the proportion of each mycorrhizal association type per grid cell and created a diversity index to explore their spatial distribution and association with abiotic factors based on LMs.ResultsThe diversity of mycorrhizal associations increased with altitude and peaked around 3000 m, in an ecotone belt known as the subpáramo recognised by the high abundance of Ericaceae species. Soil carbon stock and soil total nitrogen were also positively correlated with the diversity of mycorrhizal types. Moreover, the abundance of arbuscular mycorrhizal plants was highest at low elevations and increased with the proportion of nitrogen‐fixing plants per cell.Main ConclusionsOur results indicate that mycorrhizal associations gradually change along altitudinal gradients in the tropical Andes. Climatic factors and the interactions between climatic and edaphic factors have the greatest explanatory power to predict the distribution of types of mycorrhizal associations along the altitudinal gradient. Based on these results we expect that climate change could potentially alter the distribution of mycorrhizal types in tropical mountains with unknown consequences for ecosystem functions.

Arbuscular mycorrhizal fungal inoculum and N2-fixing plants in ecological reclamation of arid mining areas: nutrient limitation of the moss biocrust microbiome.

Ecoenzymatic stoichiometry can reflect the ability of soil microorganisms to acquire energy and nutrients and to determine their response to environmental stresses. However, the drivers of metabolic limitation of the moss biocrust microbiome during the ecological restoration of coal mining areas are poorly understood. Therefore, in this study, enzymatic stoichiometry modeling and high-throughput sequencing were used to simultaneously determine moss biocrust microbial metabolic limitation and its relationship with moss biocrust nutrients and arbuscular mycorrhizal fungal (AMF) diversity in five arid and semi-arid revegetation types (Hippophae rhamnoides, Amorpha fruticosa, Cerasus humilis, Cerasus szechuanica, and Xanthoceras sorbifolium) and two microbial treatments (AMF-inoculated and uninoculated). The activities of moss biocrust carbon (C)-, nitrogen (N)-, and phosphorus (P)-acquiring enzymes and organic carbon fractions in the AMF-inoculated treatment were significantly higher than those in the uninoculated control. Moss biocrust microbial community C and P limitations were observed in the five revegetation types, with lower limitation in general in the AMF-inoculated treatment. Dinitrogen-fixing plants (Amorpha fruticosa and Hippophae rhamnoides) significantly mitigated moss biocrust microbiome C and P limitation, especially in the AMF-inoculated treatment. Furthermore, partial least squares path modeling (PLS-PM) shows that moss biocrust organic carbon fractions (- 0.73 and - 0.81 of the total effects, respectively) and AMF diversity (- 0.73 and - 0.81 of the total effects) had negative effect on microbial C and P limitation, suggesting that more efficient active nutrients and AMF diversity are important factors alleviating limitation of moss biocrust microbial metabolism. This indicates that moss biocrust microbial communities under N2-fixing species with AMF inoculation were more stable under environmental stress; thus, AMF inoculation and/or N2-fixing plants may be recommended as preferred options for the ecological restoration of arid mining areas.

Investigation of the impact of dual inoculations of arbuscular mycorrhizal fungi and plant growth-promoting rhizobacteria on drought tolerance of maize grown in a compost-amended field under Mediterranean conditions.

In the current context of rapid climate change, water scarcity and soil poverty are becoming increasingly alarming, leading to growing losses of 30-50% of global agricultural production. It is imperative to find environmentally-friendly approaches for improving plant tolerance to drastic conditions, particularly in arid and semi-arid Mediterranean regions. Biostimulants based on symbiotic microbes are emerging as effective strategies for improving tolerance and agricultural productivity. This study aims to evaluate the effects of single and double inoculation of arbuscular mycorrhizal fungi (My) and plant growth-promoting bacteria (Ba) on the growth, physiological and biochemical traits of maize crop grown in compost (Co) amended soil under two irrigation regimes: well-watered (WW: 100% of crop evapotranspiration [ETc]) and drought-stressed (DS: 50% ETc) using drip irrigation system. Reducing irrigation to 50% reduced shoot dry weight (SDW), root dry weight (RDW), 1,000-grains weight (TGW) and grain yield (Y). However, Ba alone increased SDW by 63%, while CoMyBa improved RDW, TGW and Y by 197, 43 and 175%, respectively compared with the control under DS conditions. Dual inoculation boosted root colonization intensity, normalized difference vegetation index (NDVI), total chlorophyll and leaf area of maize seedlings in compost-amended soil, compared to the controls. The application of Ba significantly reduced hydrogen peroxide and malondialdehyde by 46%, in maize seedlings grown in compost-amended soil, compared to the controls under DS. Our results indicated that My and Ba significantly boost the ability of maize to tolerate drought by improving water supply and physiology and stimulating the accumulation of organic and inorganic osmolytes, as well as improving the properties of soils such as cation exchange capacity particularly amended by Co. The dual inoculations were the most effective and represent an environmentally-friendly and relatively inexpensive approach to optimizing agricultural production and soil restoration programs in Mediterranean regions.

Potential Regulatory Effects of Arbuscular Mycorrhizal Fungi on Lipid Metabolism of Maize in Response to Low-Temperature Stress.

The specific mechanisms underlying membrane lipid remodeling and changes in gene expression induced by arbuscular mycorrhizal fungi (AMF) in low-temperature-stressed plants are still unclear. In this study, physiological, transcriptomic, and lipidomic analyses were used to elucidate the physiological mechanisms by which AMF can enhance the adaptation of maize plants to low-temperature stress. The results showed that the relative electrical conductivity and malondialdehyde content of maize leaves were decreased after the inoculation with AMF, indicating that AMF reduced the peroxidation of membrane lipids and maintained the fluidity of the cell membrane. Transcriptomic analysis showed the presence of 702 differentially expressed genes induced by AMF in maize plants exposed to low-temperature stress. Furthermore, lipidomic analysis revealed changes in 10 lipid classes in AMF-inoculated maize plants compared with their noninoculated counterparts under low-temperature stress conditions. Lipid remodeling is an important strategy that arbuscular mycorrhizal plants adopt to cope with low-temperature stress.

Assessing the potential role of arbuscular mycorrhizal fungi in improving the phytochemical content and antioxidant properties in Gomphrena globosa

Strategies to increase the secondary metabolite production, obtained from medicinal plants has been the topic of research in recent years. The symbiotic interaction between arbuscular mycorrhizal fungi and plants allows host-fungus pairings to enhance secondary metabolite synthesis. Therefore, the current study investigated the effect of inoculating two distinct AMF species discretely as well as in conjunction on the flower-derived secondary metabolites in Gomphrena globosa. The findings showed that the plants inoculated with combined treatment exhibited higher total phenolic (50.11 mg GAE/g DW), flavonoids (29.67 mg QE/g DW), saponins (122.55 mg DE/g DW), tannins (165.71 TAE/g DW) and terpenoid (8.24 mg LE/g DW) content in the methanolic extract. HPTLC examination showed the existence of kaempferol and benzoic acid with the highest amount (0.90% and 5.83% respectively) observed in the same treatment. FTIR analysis revealed functional group peaks with increased peak intensity in the combination treatment. Higher antioxidant activities such as DPPH (IC50: 401.39 µg/mL), ABTS (IC50: 71.18 µg/mL) and FRAP (8774.73 µM Fe (II) equivalent) were observed in the methanolic extract of combined treatment. To our knowledge, this is the first study on the impact of AMF inoculation on bioactive compounds and antioxidant activities in G. globosa flowers. Moreover, this study could lead to the development of novel pharmaceuticals and herbal remedies for various diseases.

Synergism or Antagonism: Do Arbuscular Mycorrhizal Fungi and Plant Growth-Promoting Rhizobacteria Work Together to Benefit Plants?

In agriculture, abiotic and biotic stress reduce yield by 51–82% and 10–16%, respectively. Applications of biological agents such as plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) can improve plant growth. Applications of lone PGPR and AMF also help plants resist abiotic and biotic stressors. The reports for dual inoculation of AMF and PGPR to benefit plants and tackle stressors are largely unknown. It is speculated that PGPR colonization in plants enhances AMF infection during dual AMF and PGPR application, although increased AMF colonization does not always correlate with the increased benefits for the plant hosts. Further research is needed regarding molecular mechanisms of communication during dual inoculations, and dual-inoculation enhancement of induced systemic resistance under pathogen stress, to understand how dual inoculations can result in enhanced plant benefits. The influence of application timing of AMF and PGPR dual inoculations on mitigating abiotic and biotic stress is also not well understood. This review documents the factors that govern and modulate the dual application of AMF and PGPR for plant benefits against stress responses, specifically abiotic (drought) stress and stress from pathogen infection.

Interactive effects of arbuscular mycorrhizal fungi (AMF) and plant growth promoting bacteria (PGPB) on the alleviation of salt stress in wheat

Interactive effects of arbuscular mycorrhizal fungi (AMF) and plant growth promoting bacteria (PGPB) on the alleviation of salt stress in wheat

What determines transfer of carbon from plants to mycorrhizal fungi?

Biological Market Models are common evolutionary frameworks to understand the maintenance of mutualism in mycorrhizas. 'Surplus C' hypotheses provide an alternative framework where stoichiometry and source-sink dynamics govern mycorrhizal function. A critical difference between these frameworks is whether carbon transfer from plants is regulated by nutrient transfer from fungi or through source-sink dynamics. In this review, we: provide a historical perspective; summarize studies that asked whether plants transfer more carbon to fungi that transfer more nutrients; conduct a meta-analysis to assess whether mycorrhizal plant growth suppressions are related to carbon transfer; and review literature on cellular mechanisms for carbon transfer. In sum, current knowledge does not indicate that carbon transfer from plants is directly regulated by nutrient delivery from fungi. Further, mycorrhizal plant growth responses were linked to nutrient uptake rather than carbon transfer. These findings are more consistent with 'Surplus C' hypotheses than Biological Market Models. However, we also identify research gaps, and future research may uncover a mechanism directly linking carbon and nutrient transfer. Until then, we urge caution when applying economic terminology to describe mycorrhizas. We present a synthesis of ideas, consider knowledge gaps, and suggest experiments to advance the field.

Response of wheat to arbuscular mycorrhizal fungi inoculation and biochar application: Implications for soil carbon sequestration

The sequestration of atmospheric CO₂ in soil is suggested as an effective climate change mitigation strategy. Biochar application shows promise in this regard, while the role of fungi in soil carbon cycling and sequestration is also under investigation. Using a novel high-throughput plant phenomics approach, we explore the impact of arbuscular mycorrhizal fungi (AMF) inoculation and biochar application on wheat growth and soil carbon, guided by one of the leading global carbon credit schemes. Wheat was successfully colonised by AMF, achieving an average root length colonisation of 35.9%. We uncover an indirect fungal-mediated pathway to soil carbon sequestration, with mycorrhizal plants generating more biomass across all soil treatments without yield penalties, suggesting colonised plants deliver more plant derived carbon to the soil, potentially leading to long-term soil carbon gains. Conversely, fungal-driven carbon loss occurred, significantly reducing soil carbon accumulation in unamended soil, but not in biochar-amended soil, suggesting that biochar moderates fungal activity and positively impacts the soil carbon balance. While both biochar and AMF enhance plant growth, their direct effects on soil carbon are complex. Although biochar did not significantly increase soil carbon stocks beyond its own contribution, its ability to regulate fungal activity could play an important role in influencing soil carbon sequestration.