Tobacco is a significant economic crop cultivated in various regions of China. Arbuscular mycorrhizal fungi (AMF) can establish a symbiotic relationship with tobacco and regulate its growth. However, the influences of indigenous AMF on the growth and development of tobacco and their symbiotic mechanisms remain unclear. In this study, a pot inoculation experiment was conducted, revealing that six inoculants - Acaulospora bireticulata(Ab), Septoglomus viscosum(Sv), Funneliformis mosseae(Fm), Claroideoglomus etunicatum(Ce), Rhizophagus intraradices(Ri), and the mixed inoculant (H) - all formed stable symbiotic relationships with tobacco. These inoculants were found to enhance the activities of SOD, POD, PPO, and PAL in tobacco leaves, increase chlorophyll content, IAA content, CTK content, soluble sugars, and proline levels while reducing malondialdehyde content. Notably, among these inoculants, Fm exhibited significantly higher mycorrhizal infection density, arbuscular abundance, and soil spore density in the root systems of tobacco plants compared to other treatments. Membership function analysis confirmed that Fm had the most pronounced growth-promoting effect on tobacco. The transcriptome analysis results of different treatments of CK and inoculation with Fm revealed that 3,903 genes were upregulated and 4,196 genes were downregulated in the roots and stems of tobacco. Enrichment analysis indicated that the majority of these genes were annotated in related pathways such as biological processes, molecular functions, and metabolism. Furthermore, differentially expressed genes associated with auxin, cytokinin, antioxidant enzymes, and carotenoids were significantly enriched in their respective pathways, potentially indirectly influencing the regulation of tobacco plant growth. This study provides a theoretical foundation for the development and application of AMF inoculants to enhance tobacco growth.

Arbuscular mycorrhizal (AM) fungi are important plant symbionts that provide plants with nutrients and water as well as support plant defences against pests and disease. Consequently, they present a promising alternative to using environmentally damaging and costly fertilisers and pesticides in agricultural systems. However, our limited understanding of how agricultural practices impact AM fungal diversity and functions is a key impediment to using them effectively in agriculture. We assessed how organic and conventional agricultural management systems shaped AM fungal communities. We also investigated how AM fungal communities derived from these agricultural management systems affected crop biomass and development. Six soil samples from five organically and five conventionally managed agricultural sites were used to cultivate Sorghum bicolor. Plant growth, plant nutrient concentrations and AM fungal colonisation rates were analysed alongside DNA metabarcoding of community composition. We observed that soil from conventional agricultural fields resulted in a pronounced reduction in sorghum biomass (-53.6%) and a significant delay in flowering compared to plants grown without AM fungi. Sorghum biomass was also reduced with soil from the organic system, but to a lesser extent (-30%) and without a delay in flowering. Organic systems were associated with a large proportion of AM fungal taxa (50.5% of VTs) not found in conventional systems, including Diversispora (r(2) = 0.09, p < 0.001), Archaeospora (r(2) = 0.07, p < 0.001) and Glomus (r(2) = 0.25, p < 0.001) spp., but also shared a large proportion of taxa with conventional systems (42.3% of VTs). Conventional systems had relatively few unique taxa (7.2% of VTs). Our results suggest that conventional agricultural practices selected against AM fungi that were, in this context, more beneficial for host plants. In contrast, organic management practices mitigate this negative effect, likely due to the presence of specific key AM fungal taxa. However, this mitigation is only partial, as less beneficial AM fungal taxa still persist, probably due to abiotic factors associated with agricultural management and the sensitivity of AM fungi to these factors. This persistence explains why the effect is not entirely eradicated. Read the free Plain Language Summary for this article on the Journal blog.

Under saline-alkali stress conditions, inoculation with Rhizophagus irregularis or the application of biochar can both promote plant growth and improve soil physicochemical properties. However, the effects of their combined use on switchgrass growth and soil mechanical properties remain unclear. This study established four treatments: no Ri inoculation and no biochar addition (control, CK), biochar addition alone (BC), Rhizophagus irregularis inoculation alone (Ri), and their combination (RB). The aim was to investigate the effects of these treatments on the biomass, root morphology, and soil mechanical properties of switchgrass under saline-alkali stress. The results showed that compared to the CK treatment, the RB treatment significantly increased the root, stem, leaf, and total biomass of switchgrass by 67.55%, 74.76%, 117.31%, and 82.93%, respectively. Among all treatment groups, RB treatment significantly reduced soil bulk density, soil water-soluble sodium ions (Na+), soil exchangeable sodium percentage (ESP), and sodium adsorption ratio (SAR), while increasing soil porosity. Furthermore, RB treatment significantly improved infiltration rate and shear strength. Compared to the CK treatment, the stable infiltration rate and shear strength under 400 kPa vertical load increased by 70.69% and 22.5 kPa, respectively. In conclusion, the combination of Ri and biochar has the potential to improve soil mechanical properties and increase the biomass of switchgrass under saline-alkali stress.

Salt accumulation can degrade soil properties, decrease its productivity, and harm its ecological functions. Introducing salt-tolerant plant species associated with arbuscular mycorrhizal fungi (AMF) can act as an effective biological method for restoring salinized soils. AMF colonize plant roots and improve their nutrient acquisition capacity. However, there is limited knowledge on how AMF affects the production of signaling molecules, e.g., abscisic acid (ABA), salicylic acid (SA), and jasmonic acid (JA), related to plant-microbe interactions under salinity. Here, we assess the potential benefits of the AMF Rhizophagus intraradices in enhancing plant growth and nutrient uptake in addition to modulating stress hormone signaling levels (ABA, SA, and JA) of the facultative halophyte Sulla carnosa under saline conditions. Plants were grown in pots filled with soil and irrigated with 200 mM NaCl for 1 month. AMF symbiosis substantially increased the shoot dry weight (+107%), root dry weight (+67%), photosynthetic pigment content (chlorophyll a, chlorophyll b, and carotenoids), and nutrient uptake (C, N, P, K, Cu, and Zn) while significantly limiting the increase in the shoot Na+ concentration and H2O2 content caused by salinity stress. Mycorrhizal symbiosis significantly enhanced the root and shoot SA levels by 450% and 32%, respectively, compared to the stressed non-inoculated plants, potentially contributing to enhanced systemic resistance and osmotic adjustment under saline conditions. Salt stress increased the shoot ABA content, especially in R. intraradices-inoculated plants (113% higher than in stressed non-mycorrhizal plants). These findings confirm that AMF mitigated the adverse effects of salinity on S. carnosa by increasing the SA and ABA levels and reducing oxidative damage.

Salinity stress significantly impacts agricultural productivity by damaging key plant mechanisms like photosynthesis, osmotic balance, and enzymatic activity. Withania somnifera (L.) Dunal, valued in Ayurveda for its anti-carcinogenic withanolides such as withaferin A, faces reduced yields due to soil salinity in India. Sustainable, eco-friendly methods are needed to mitigate salt stress and improve economic yield, as conventional approaches are environmentally unsustainable for long-term productivity. This study hypothesizes that plant growth-promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF) could effectively reduce salinity stress and enhance withaferin A production. The study evaluates the effects of nitrogen-fixing bacteria (Azotobacter chroococcum), phosphate-solubilizing bacteria (Bacillus amyloliquefaciens), potassium-solubilizing bacteria (Enterobacter esburiae), and a mycorrhizal consortium under saline (4.5 dS m-1) and non-saline conditions. The 4.5 dS m-1 sodium chloride salinity dose significantly (p < 0.05) reduced growth attributes and increased malondialdehyde (p < 0.001) (MDA) content, electrolytic leakage (p < 0.0001) (EL), and sodium-potassium ratio (p < 0.001) by 113.38%, 79.51%, and 114.85%, respectively, compared to control. Among all the biofertilizer treatments, AMF inoculation most effectively improved (p < 0.05) growth parameters and decreased MDA (p < 0.01), EL (p < 0.001), and sodium-potassium ratio (p < 0.0001) by 69.99%, 21.42%, and 66.96%, respectively. Under salinity stress, AMF inoculation maximally increased (p < 0.0001) withaferin A by 49.07%, while PGPB increased (p < 0.05) it upto 34.54%. The findings suggest that AMF and PGPB alleviate salinity stress by reducing lipid peroxidation and electrolyte leakage, regulating the sodium-potassium ratio, and enhancing withanolide production in W. somnifera. Thus, microbial inoculation offers a sustainable, eco-friendly approach to improving the growth and yield of secondary metabolites in W. somnifera in salt-affected regions.

Cadmium (Cd) is a highly toxic agricultural pollutant that inhibits the growth and development of plants. Arbuscular mycorrhizal fungi (AMF) can enhance plant tolerance to Cd, but the regulatory mechanisms in Allium fistulosum (green onion) are unclear. This study used a Cd treatment concentration of 1.5 mg center dot kg-1, which corresponds to the risk control threshold for soil pollution in Chinese agricultural land, to examine the effects and molecular mechanisms of AMF inoculation on the growth and physiology of green onion under Cd stress. AMF formed an effective symbiotic relationship with green onion roots under Cd stress, increased plant biomass, improved root structure and enhanced root vitality. AMF-colonized green onion had reduced Cd content in roots and leaves by 63.00 % and 46.50 %, respectively, with Cd content being higher in the roots than in the leaves. The ameliorative effect of AMF on Cd toxicity was mainly due to a reduction in malondialdehyde content in leaves (30.12 %) and an enhancement of antioxidant enzyme activities (peroxidase, catalase, superoxide dismutase, glutathione reductase and reduced glutathione) that mitigated damage from excessive reactive oxygen species. In addition, AMF induced secretion of easily extractable glomalin soil protein and total glomalin-related soil protein and inhibited the translocation of Cd to the shoots. Transcriptomic and metabolomic correlation analyses revealed that differentially expressed genes and metabolites in AMF-inoculated green onion under Cd stress were predominantly enriched in the phenylpropanoid biosynthesis and phenylalanine metabolism pathways, upregulated the expression of the HCT, PRDX6, HPD, MIF, and HMA3 genes, and accumulation of the phenylalanine, L-tyrosine, and 1-O-sinapoyl-beta-glucose metabolites. Thus, AMF enhance Cd tolerance in green onions by sequestering Cd in roots, restricting its translocation, modulating antioxidant defenses and inducing the expression of genes involved in the phenylpropanoid biosynthesis and phenylalanine metabolism pathways. Collectedly, we for the first time revealed the mechanism of AMF alleviating the toxicity of Cd to green onion, providing a theoretical foundation for the safe production and sustainable cultivation of green onion in Cdcontaminated soils.

This study aims to explore the effects of arbuscular mycorrhizal fungi (AMF) on the growth of Iris pseudacorus L. and treatment efficacy in constructed wetlands (CWs) subjected to stress from per-and poly-fluoroalkyl substances (PFASs). The findings reveal that PFASs exposure induces oxidative damage and inhibits the growth of I . pseudacorus. However, AMF symbiosis enhances plant tolerance to PFAS stress by modulating oxidative responses. AMF treatment not only promoted plant growth but also improved photosynthetic efficiency under PFAS exposure. Compared to non-AMF treatment, those with AMF treatment exhibited significantly increased levels of peroxidases and antioxidant enzymes, including peroxidase and superoxide dismutase, along with a notable reduction in lipid peroxidation. Additionally, AM symbiosis markedly enhanced the efficacy of CWs in the remediation of wastewater under PFASs-induced stress, with removal efficiencies for COD, TP, TN, and NH4+- N increasing by 19-34%, 67-180%, 106-137%, and 25-95%, respectively, compared to the AMF- treatments. In addition, the metabolic pathways of PFASs appeared to be influenced by their carbon chain length, with long- chain PFASs like perfluorooctanoic acid (PFOA) and perfluoro anionic acid (PFNA) exhibiting more complex pathways compared to short-chain PFASs such as perfluoro acetic acid (PFPeA), and perfluoro hexanoic acid (PFHpA). These results suggest that AMF-plant symbiosis can enhance plant resilience against PFAS-induced stress and improve the pollutant removal efficiency of CWs. This study highlights the significant potential of AMF in enhancing environmental remediation strategies, providing new insights for the more effective management of PFAS-contaminated ecosystems.

The challenge of soil salinization and alkalization, with its significant impact on crop productivity, has raised growing concerns with global population growth and enhanced environmental degradation. Although arbuscular mycorrhizal fungi (AMF) and calcium ions (Ca2+) are known to enhance plant resistance to stress, their combined effects on perennial ryegrass' tolerance to salt and alkali stress and the underlying mechanisms remain poorly understood. This study aimed to elucidate the roles of Arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis and exogenous Ca2+ application in molecular and physiological responses to salt-alkali stress. AM symbiosis and exogenous Ca2+ application enhanced antioxidant enzyme activity and non-enzymatic components, promoting reactive oxygen species (ROS) scavenging and reducing lipid peroxidation while alleviating oxidative damage induced by salt-alkali stress. Furthermore, they enhanced osmotic balance by increasing soluble sugar content (Proportion of contribution of the osmotic adjustment were 34 similar to 38 % in shoots and 30 similar to 37 % in roots) under salt stress and organic acid content (Proportion of contribution of the osmotic adjustment were 32 similar to 36 % in shoots and 37 similar to 42 % in roots) under alkali stress. Changes in organic solute and inorganic cation-anion contents contributed to ion balance, while hormonal regulation played a role in these protective mechanisms. Moreover, the protective mechanisms involved activation of Ca2+-mediated-mediated signaling pathways, regulation of salt-alkali stress-related genes (including LpNHX1 and LpSOS1), increased ATPase activity, elevated ATP levels, enhanced Na+ extrusion, improved K+ absorption capacity, and a reduced Na+/K+ ratio, all contributing to the protection of photosynthetic pigments and the enhancement of photosynthetic efficiency. Ultimately, the combined application of exogenous Ca2+ and AMF synergistically alleviated the inhibitory effects of salt-alkali stress on perennial ryegrass growth. This finding suggested that exogenous Ca2+ may participate in the colonization of perennial ryegrass plants by R. irregularis, while AM symbiosis may activate Ca2+ pathways. Consequently, the combined treatment of AM and Ca2+ is beneficial for enhancing plant regulatory mechanisms and increasing crop yield under salt-alkali stress.

AimThe unregulated use of rare earth elements, such as Europium (Eu), may result in their build-up in soils. Here, we investigated how Eu affects wheat growth, photosynthesis, and redox homeostasis and how Arbuscular mycorrhizal fungi (AMF) may influence these processes.MethodsThe wheat plants were grown in soil with 1.09 mmol Eu3+/kg and/or AMF inoculation. The study is mainly based on a comprehensive examination of the detailed biochemical and metabolic mechanisms underlying the Eu stress mitigating impact of Eu by AMF in wheat plants.ResultsSoil contamination with Eu significantly induced a reduction in biomass accumulation and photosynthesis-related parameters, including photosynthetic rate (61%) and chlorophyll content (24.6%). On the other hand, AMF could counteract Eu's induced growth and photosynthesis inhibition. Under Eu stress, AMF colonization significantly increased fresh and dry weights by 43% and 23.5%, respectively, compared to Eu treatment. AMF colonization also induced minerals (e.g., Ca, K, Zn, and N) uptake under control and Eu stress conditions. By bolstering the antioxidant defense mechanisms, such as ROS-scavenging metabolites (flavonoids and polyphenols), AMF mitigated Eu-induced oxidative damage. In terms of the primary metabolites, organic acids, essential amino acids, and unsaturated fatty acids were increased by AMF colonization, particularly under Eu stress conditions.ConclusionApplying AMF is a workable approach for reducing Eu toxicity in wheat plants.

Global warming is contributing to an increase in the frequency of extreme climate events, leading to more frequent droughts that pose significant abiotic stressors affecting the growth and yield of sugar beet. To address the detrimental effects of drought stress on sugar beet seedlings, this study simulated a drought environment and examined the impact of arbuscular mycorrhizal fungi (AMF) symbiosis on seedling growth. The findings revealed that AMF inoculation under drought conditions enhanced the photosynthesis rate and increased the content of photosynthetic pigments in the leaves of sugar beet. Additionally, it effectively mitigated cell membrane damage in the seedlings, elevated the levels of osmoregulatory substances, and enhanced antioxidant enzyme activities in both leaves and roots. The inoculation of AMF regulates the physiological processes associated with sugar beet growth, alleviates the adverse effects of drought stress, and promotes seedling development. Consequently, AMF can be regarded as a valuable bioregulator in sugar beet cultivation under drought conditions, providing significant practical benefits for improving sugar beet yield.