Impact Of Arbuscular Mycorrhizal Fungi Research Articles

Increasing atmospheric CO2 differentially supports arsenite stress mitigating impact of arbuscular mycorrhizal fungi in wheat and soybean plants (Chemosphere, Volume 296, June 2022, 134044)

Increasing atmospheric CO2 differentially supports arsenite stress mitigating impact of arbuscular mycorrhizal fungi in wheat and soybean plants (Chemosphere, Volume 296, June 2022, 134044)

The impact of arbuscular mycorrhizal fungi and endophytic bacteria on peanuts under the combined pollution of cadmium and microplastics

It remains unclear how symbiotic microbes impact the growth of peanuts when they are exposed to the pollutants cadmium (Cd) and microplastics (MPs) simultaneously. This study aimed to investigate the effects of endophytic bacteria Bacillus velezens SC60 and arbuscular mycorrhizal fungus Rhizophagus irregularis on peanut growth and rhizosphere microbial communities in the presence of Cd at 40 (Cd40) or 80 (Cd80) mg kg−1 combined without MP or the presence of low-density polyethylene (LDPE) and poly butyleneadipate-co-terephthalate (PBAT). This study assessed soil indicators, plant parameters, and Cd accumulation indicators. Results showed that the application of R. irregularis and B. velezens significantly enhanced soil organic carbon and increased Cd content under the conditions of Cd80 and MPs co-pollution. R. irregularis and B. velezens treatment increased peanut absorption and the enrichment coefficient for Cd, with predominate concentrations localized in the peanut roots, especially under combined pollution by Cd and MPs. Under treatments with Cd40 and Cd80 combined with PBAT pollution, soil microbes Proteobacteria exhibited a higher relative abundance, while Actinobacteria showed a higher relative abundance under treatments with Cd40 and Cd80 combined with LDPE pollution. In conclusion, under the combined pollution conditions of MPs and Cd, the co-treatment of R. irregularis and B. velezens effectively immobilized Cd in peanut roots, impeding its translocation to the shoot.

The Synergistic Impact of Arbuscular Mycorrhizal Fungi and Compost Tea to Enhance Bacterial Community and Improve Crop Productivity under Saline-Sodic Condition.

Soil salinity has a negative impact on the biochemical properties of soil and on plant growth, particularly in arid and semi-arid regions. Using arbuscular mycorrhizal fungi (Glomus versiform) and foliar spray from compost tea as alleviating treatments, this study aimed to investigate the effects of alleviating salt stress on the growth and development of maize and wheat grown on a saline-sodic soil during the period of 2022/2023. Six treatments were used in the completely randomized factorial design experiment. The treatments included Arbuscular mycorrhizal fungus (AMF0, AMF1) and varied concentrations of compost tea (CT0, CT50, and CT100). AMF colonization, the bacterial community and endosphere in the rhizosphere, respiration rate, growth parameters, and the productivity were all evaluated. The application of AMF and CT, either separately or in combination, effectively mitigated the detrimental effects caused by soil salinity. The combination of AMF and CT proved to be highly efficient in improving the infection rate of AMF, the bacterial community in the rhizosphere and endosphere, growth parameters, and grain yield of maize and wheat. Therefore, it can be proposed that the inoculation of mycorrhizal fungi with compost tea in saline soils is an important strategy for enhancing salt tolerance in maize and wheat plants through improving microbial activity, the infection rate of AMF, and overall maize and wheat productivity.

Mycorrhizal status and host genotype interact to shape plant nutrition in field grown maize (Zea mays ssp. mays)

Arbuscular mycorrhizal fungi (AMF) establish symbioses with the major cereal crops, providing plants with increased access to nutrients while enhancing their tolerance to toxic heavy metals. However, not all plant varieties benefit equally from this association. In this study, we used quantitative trait loci (QTL) mapping to evaluate the combined effect of host genotypic variation (G) and AMF across 141 genotypes on the concentration of 20 mineral elements in the leaves and grain of field grown maize (Zea mays spp. mays). Our mapping design included selective incorporation of a castor AMF-incompatibility mutation, allowing estimation of AMF, QTL and QTLxAMF effects by comparison of mycorrhizal and non-mycorrhizal plants. Overall, AMF compatibility was associated with higher concentrations of boron (B), copper (Cu), molybdenum (Mo), phosphorus (P), selenium (Se) and zinc (Zn) and lower concentrations of arsenic (As), iron (Fe), magnesium (Mg), manganese (Mn), potassium (K) and strontium (Sr). In addition to effects on individual elements, pairwise correlation matrices for element concentration differed between mycorrhizal and non-mycorrhizal plants. We mapped 22 element QTLs, including 18 associated with QTLxAMF effects that indicate plant genotype-specific differences in the impact of AMF on the host ionome. Although there is considerable interest in AMF as biofertilizers, it remains challenging to estimate the impact of AMF in the field. Our design illustrates an effective approach for field evaluation of AMF effects. Furthermore, we demonstrate the capacity of the ionome to reveal host genotype-specific variation in the impact of AMF on plant nutrition.

Arbuscular mycorrhizal inoculation alleviates water competition between adjacent plants in the mixed planting system

Exploring the water use strategies of different plant species is very important in understanding the mechanisms of soil-plant interactions in water-limited ecosystems. There is limited information on changes in plant water use in mixtures of species, and little is known of the role of arbuscular mycorrhizal fungi in regulating the water use strategies of host plants in mixtures. The water use strategies of three plant communities in arid and semi-arid mining areas were investigated. These were Medicago sativa (alfalfa) in monoculture (A), Caragana korshinskii (Korshinsk pea shrub) in monoculture (C), and Medicago sativa + Caragana korshinskii in mixture (MIX). Each plant community was inoculated with an arbuscular mycorrhizal fungus or uninoculated to determine the regulation of plant water use strategy by the fungus. There was a significant difference in the use of soil water by both plant species in mixture compared with monoculture (P < 0.05). In the mixture there was significant competition for water between depths 0–40 cm and 40–100 cm. Both species took up more water from the surface soil than in monoculture. Mycorrhizal inoculation reduced the dependence of the plants on surface soil water, effectively alleviated the competition for water between the two plant species in mixture. The results indicate that the impact of arbuscular mycorrhizal fungi on the water use strategies of different plant species in mixtures should be considered when ecological restoration of vegetation is carried out in arid and semi-arid areas.

Metagenomics reveal arbuscular mycorrhizal fungi altering functional gene expression of rhizosphere microbial community to enhance Iris tectorum's resistance to Cr stress

Chromium (Cr) can disrupt a plant's normal physiological and metabolic functions and severely impact the microenvironment. However, limited studies have investigated the impact of arbuscular mycorrhizal fungi (AMF) inoculation on the rhizosphere microorganisms of Iris tectorum under Cr stress, and the mechanisms of how rhizosphere microorganisms interact with hosts and contaminants. In this study, we investigated the effects of AMF inoculation on the growth, absorption of nutrients and heavy metals, and functional genes of the rhizosphere microbial community of I. tectorum under Cr stress in a greenhouse pot experiment. The results showed that AMF significantly increased the biomass and nutrient levels of I. tectorum, while decreasing the content of Cr in soil. Furthermore, metagenome analysis demonstrated significant changes in the structure and composition of the rhizosphere microbial community after AMF formed a mycorrhizal symbiosis system with the I. tectorum. Specifically, the abundance of functional genes related to nutrient cycling (N, P) and heavy metal resistance (chrA and arsB), as well as the abundance of heavy metal transporter family (P-atPase, MIT, CDF, and ABC) in the rhizosphere microbial community were up-regulated and their expression. Additionally, the synergies between rhizosphere microbial communities were regulated, and the complexity and stability of the rhizosphere microbial ecological network were enhanced. This study provides evidence that AMF can regulate rhizosphere microbial communities to improve plant growth and heavy metal stress tolerance, and helps us to understand the potential mechanism of wetland plant remediation of Cr-contaminated soil under AMF symbiosis.

The salutary impacts of AMF species, rock phosphates (RP), and organic matter (FYM) fertilizers on the development and chemical behavior of Mentha arvensis L.

Phosphorus availability from rock phosphate (RP) can be improved through composting with organic manure and phosphate-solubilizing microorganisms in the soil to improve phosphorus status and plant growth in alkaline and calcareous soils of Pakistan. As a result, an experiment was carried out to determine the impact of arbuscular mycorrhizal fungi (AMF) species as biofertilizers on Mentha arvensis when rock phosphate and organic manure (FYM) levels were varied (0%, 50%, and 100%). In M. arvensis, plant growth performance, mycorrhizal dependence values, oil output, mineral, and nutritional analysis, infection, and spore density were evaluated. The experiment was designed with eight RCBD treatments and five replications. Compared to non-inoculated plants, the growth responses of M. arvensis to AM inoculation with rock phosphate and organic manure were pronounced. Mycorrhizal dependencies increased with increasing levels of rock phosphate and organic manure, which were 40.82% and 46.92%, respectively. The results showed that M. arvensis produced a higher percentage of essential oil for AMF inoculation at higher and lower levels of rock phosphate and organic manure. In terms of nutrient uptake by mycorrhizal plants, there were a significant improvement in macro (P, N, K, Mg) and micronutrients (Fe, Cu, and Zn) in all tested mycorrhizal plants compared to non-treated plants. The nutritional value of M. arvensis rises with the amount of fertilizer added. Results proved that as fertility levels rise, the number of spores (150 to 190/100 g of soil) and the percentage of association (70.51 to 95.23%) increase in Mentha arvensis. The findings imply that inoculating plants with AMF might increase phosphorus solubility from rock phosphate and organic manure. Local rock phosphate and organic manure may be used to reduce reliance on expensive commercial synthetic fertilizers while also increasing crop yields.

Mycorrhizal symbiosis-induced abiotic stress mitigation through phosphate transporters in Solanum lycopersicum L

Arbuscular mycorrhizal (AM) symbiosis and abiotic stress mitigation have intrigued researchers for more than a century, but how different phosphate transporters, such as members of the Pht1 gene family, are influenced during the combined presence of AM fungi and stress is not well known. In this study, the impact of AM fungi (Funneliformis mosseae) on tomato plants under water deficit and heat stress was investigated via observing the physiological changes and applying spectrophotometric and quantitative real-time PCR methods, with a focus on phosphate transporters (Pht1;1, Pht1;3, Pht1;4, Pht1;6, Pht1;7 and Pht1;8). Moreover, genes encoding heat-responsive proteins (HSFA2 and HSP70) and aquaporins (PIP2.5 and PIP2.7) were also studied. On the basis of our results, AM fungi seemingly mitigated heat and combined (heat and water deficit) stresses through the mediation of the expression of Pht1 family phosphate transporter genes. In addition to the Pht1;3 and Pht1;4 genes, Pht1;7 also seems to be an AM fungus-inducible phosphate transporter gene. The results of this study may provide insights into the behavior of phosphate transporter gene family members and a potential strategy to enhance the vigor of tomato plants through increased phosphorous uptake under heat stress, water deficit and heat and water deficit combined.

Impact of Arbuscular Mycorrhizal Fungi, Phosphate Solubilizing Bacteria and Selected Chemical Phosphorus Fertilizers on Growth and Productivity of Rice

Phosphorus is the second most significant macro nutrient in rice productivity. Phosphorus fixation in Egyptian soil makes it unavailable for rice to absorb. The goal of this study was to examine the effects of microbial and chemical sources of phosphorus fertilizers on the Egyptian Sakha 106 rice cultivar by applying different sources of phosphorus to increase the bioavailability of soil phosphorus for plants and to allow it to be fixed biologically to change it from an insoluble form to a soluble and available form for rice to absorb. So, in the 2019 and 2020 seasons, a field experiment was conducted at the experimental farm of Sakha Agricultural Research Station, Sakha, Kafr El-Sheikh, Egypt. The experiment was carried out using a Randomized Complete Block Design with four replications to determine the best phosphorus source for rice and soil among various treatments, which included 100% single super phosphate (SSP) basal application (P1), 75% single super phosphate (SSP) basal application (P2), P2 + phosphate-solubilizing bacteria (PSBs) top-dressing, P2 + arbuscular mycorrhizal fungi (AMFs) top-dressing P2 + phosphorus nanoparticles (PNPs) foliar spraying, P2 + phosphoric acid (PA) foliar spraying, P2 + (PSBs + AMFs) foliar spraying, P2 + (PSBs + PNPs) foliar spraying, P2 + (PSBs + PA) foliar spraying, P2 + (PNPs + PA) foliar spraying, P2 + (PSBs + PNPs + PA) foliar spraying and zero-phosphorus fertilizer. The results showed that the highest values were mostly obtained using the combination of 75% SSP basal application with the foliar spraying of PSBs, PNPs and PA, with substantial beneficial impacts on the leaf area index (3.706 and 3.527), dry matter accumulation (464.3 and 462.8 g m2), plant height (96.33 and 95.00 cm), phosphorus uptake in grain (24.3 and 24.49 Kg ha−1), phosphorus uptake in straw (17.7 and 17.0 Kg ha−1) and available phosphorus in the soil at harvest (21.75 and 21.70 ppm) in the 2019 and 2020 seasons, respectively; moreover, 75% SSP basal application with the foliar spraying of PSBs, PNPs and PA or 100% SSP basal application alone improved the number of panicles (506.3 or 521.1 and 521.9 or 547.1 m−2), filled grain weight (3.549 or 3.534 and 3.627 or 3.767 g panicle−1), the percentage of filled grain (96.19 or 96.47 and 95.43 or 96.24%), grain yield (9.353 or 9.221 and 9.311 or 9.148 t ha−1) and straw yield (11.51 or 11.46 and 11.82 or 11.69 t ha−1) in the 2019 and 2020 seasons, respectively. Chemical P fertilizers combined with the foliar spraying of PSBs, PNPs and PA obtained the highest crop productivity and improved most of the examined characteristics without any significant changes with respect to chemical P application alone in some other characteristics, followed by 75% SSP + top-dressing with PSBs + AMFs. The treatment that included the combination of 75% SSP basal application and the foliar spraying of PSBs +PNPs +PA is recommended, as it might be utilized to boost rice yield by solubilizing P in soil and increasing the absorption efficiency. In addition, it reduces chemical P fertilizers by 25%, which would guarantee a cleaner environment and soil conservation.

The impact of arbuscular mycorrhizal fungi on tomato plant resistance against Tuta absoluta (Meyrick) in greenhouse conditions

• Interaction was observed between Tuta absoluta and arbuscular mycorrhizal fungi (AMF). • Mixed species of AMF made plants relatively more resistant against Tuta absoluta . • A lower population of insect was established on the plants inoculated with AMF. • Less insects in plants with AMF was likely due to the unsuitability of the host. The symbiotic relationship between plants and arbuscular mycorrhizal fungi (AMF) improves plant growth and increases its resistance to pests and diseases. Mycorrhizal fungi are among the specialized fungi associated with the rhizosphere and are completely dependent on plant organic carbon. In this research tomato, Solanum lycopersicum L. was used as the host plant to evaluate the interaction effects between inoculation of tomato plant with AMF and feeding of tomato leaf miner, Tuta absoluta (Meyrick). In addition, plant growth parameters and growth rate of insect were assessed. The mycorrhizal treatment included a mixture of four fungal species ( Funneliformis mosseae , Rhizophagus intraradices , R. irregularis and Glomus iranicus ). The results of the experiment showed that tomato plant roots were well colonized (66.29%) by AMF and there was a significant mutual relationship between the insects feeding on the plants and the fungi. Feeding by the insects on plants inoculated with the fungus increased percentage of colonization by AMF in plants infested with the insect as compared to the control plants. The results also indicated that growth parameters and phosphorus content of the plants inoculated with fungi significantly increased compared to the control group. Moreover, significantly lower growth rate and consumption index observed in the T. absoluta larvae were fed on the leaves of plants treated with AMF compared to leaves of plants not inoculated with AMF.

Co-inoculation of biochar and arbuscular mycorrhizae for growth promotion and nutrient fortification in soybean under drought conditions

Drought is significant abiotic stress that affects the development and yield of many crops. The present study is to investigate the effect of arbuscular mycorrhizal fungi (AMF) and biochar on root morphological traits, growth, and physiological traits in soybean under water stress. Impact of AMF and biochar on development and root morphological traits in soybean and AMF spores number and the soil enzymes’ activities were studied under drought conditions. After 40 days, plant growth parameters were measured. Drought stress negatively affected soybean growth, root parameters, physiological traits, microbial biomass, and soil enzyme activities. Biochar and AMF individually increase significantly plant growth (plant height, root dry weight, and nodule number), root parameters such as root diameter, root surface area, total root length, root volume, and projected area, total chlorophyll content, and nitrogen content in soybean over to control in water stress. In drought conditions, dual applications of AMF and biochar significantly enhanced shoot and root growth parameters, total chlorophyll, and nitrogen contents in soybean than control. Combined with biochar and AMF positively affects AMF spores number, microbial biomass, and soil enzyme activities in water stress conditions. In drought stress, dual applications of biochar and AMF increase microbial biomass by 28.3%, AMF spores number by 52.0%, alkaline phosphomonoesterase by 45.9%, dehydrogenase by 46.5%, and fluorescein diacetate by 52.2%, activities. The combined application of biochar and AMF enhance growth, root parameters in soybean and soil enzyme activities, and water stress tolerance. Dual applications with biochar and AMF benefit soybean cultivation under water stress conditions.

Effect of arbuscular myccorhizal fungi on soil properties, mineral nutrition and antioxidant enzymes of olive plants under treated wastewater irrigation

The present study aimed to determine the impact of arbuscular mycorrhizal fungi (AMF) on soil and young olive plants irrigated for one year with saline treated wastewater (TWW). One-year-old olive plants were inoculated with different AMF: (i) Glomus deserticola; (ii) Gigaspora margarita and (iii) combination of G. deserticola and G. margarita. Changes were observed in the soil chemical characteristics, in particular a significant increase in the electrical conductivity and an accumulation of Na+ and Cl−. Consequently, compared to the control treatment, the Na+ and Cl− contents of young olive plants irrigated with TWW increased by 12 and 133% in the leaves and by 98 and 106% in the roots, respectively. Moreover, an increase in the antioxidant enzyme activities, malondialdehyde and H2O2 contents, and electrolyte leakage rate was observed. Interestingly, roots and leaves of olive plants inoculated with AMF and irrigated with TWW showed a lower Na+ and Cl−content, and a higher macro- and micro-nutrient content, compared to uninoculated plants. The decrease of Na+ and Cl− contents in olive plants inoculated with both G. deserticola and G. margarita was about 24 and 43% in the leaves, and about 30 and 39% in the roots, respectively. Furthermore, the AMF symbiosis enhanced the antioxidant enzymes activities (CAT and APX) and reduced the malondialdehyde and H2O2 contents.

Arbuscular mycorrhizal fungus regulates cadmium accumulation, migration, transport, and tolerance in Medicago sativa

Cadmium (Cd) pollution in croplands is a global environmental problem. Measures to improve the tolerance of sensitive crops and reduce pollutant absorption and accumulation are needed in contaminated agricultural areas, and inoculation with rhizosphere microorganisms to regulate plant resistance and heavy metal transport can provide an effective solution. A pot experiment was conducted to analyse the impact of arbuscular mycorrhizal fungi (AMF) on alfalfa oxidase activity, heavy metal resistance genes and transport proteins, metabolism, and other biochemical regulation mechanisms that lead to complexation, compartmentalisation, efflux, enrichment, and antioxidant detoxification pathways. The AMF reduced shoot and protoplasm Cd inflow, and promoted organic compound production (e.g., by upregulating HM-Res4 for 1.2 times), to complex with Cd, reducing its biological toxicity. The AMF increased the ROS scavenging efficiency and osmotic regulatory substance content of the alfalfa plants, reduced oxidative stress (ROS dereased), and maintained homeostasis. It also alleviated Cd inhibition of photosynthetic electron transport, tricarboxylic acid circulation, and nitrogen assimilation. These AMF effects improved leaf and root biomass by 43.87% and 59.71% and facilitated recovery of a conservative root economic strategy. It is speculated that AMF induces the resistance signal switch by regulating the negative feedback regulation mode of indole acetic acid upward transport and methyl jasmonate downward transmission in plants.

Overlapping Root Architecture and Gene Expression of Nitrogen Transporters for Nitrogen Acquisition of Tomato Plants Colonized with Isolates of Funneliformis mosseae in Hydroponic Production.

Understanding the impact of arbuscular mycorrhizal fungi (AMF) upon the nitrogen (N) uptake of tomato (Lycopersicum esculentum L.) plants is crucial for effectively utilizing these beneficial microorganisms in industrial hydroponic tomato production. Yet it remains unknown whether, besides fungal delivery, the AMF also affects N uptake via altered plant root growth or whether, together with changed N transporters expression of hosts, this impact is isolate-specific. We investigated tomato root architecture and the expression of LeAMT1.1, LeAMT1.2, and LeNRT2.3 genes in roots inoculated with five isolates of Funneliformis mosseae, these collected from different geographical locations, under greenhouse conditions with nutritional solution in coconut coir production. Our results revealed that isolate-specific AMF inoculation strongly increased the root biomass, total root length, surface area, and volume. Linear relationships were found between the total root length and N accumulation in plants. Furthermore, expression levels of LeAMT1.1, LeAMT1.2, and LeNRT2.3 were significantly up-regulated by inoculation with F. mosseae with isolate-specific. These results implied N uptake greater than predicted by root growth, and N transporters up-regulated by AMF symbiosis in an isolate-specific manner. Thus, an overlap in root biomass, architecture and expression of N transporters increase N acquisition in tomato plants in the symbiosis.

Increasing atmospheric CO2 differentially supports arsenite stress mitigating impact of arbuscular mycorrhizal fungi in wheat and soybean plants

Arbuscular mycorrhizal fungi (AMF) are beneficial for the plant growth under heavy metal stress. Such beneficial effect is improved by elevated CO2 (eCO2). However, the mechanisms by which eCO2 improves AMF symbiotic associations under arsenite (AsIII) toxicity are hardly studied. Herein, we compared these regulatory mechanisms in species from two agronomical important plant families – grasses (wheat) and legumes (soybean). AsIII decreased plant growth (i.e., 53.75 and 60.29% of wheat and soybean, respectively) and photosynthesis. It also increased photorespiration and oxidative injury in both species, but soybean was more sensitive to oxidative stress as indicated by higher H2O2 accumulation and oxidation of protein and lipid. eCO2 significantly improved AMF colonization by increasing auxin levels, which induced high carotenoid cleavage dioxygenase (CCDs) activity, particularly in soybean roots. The improved sugar metabolism in plant shoots by co-application of eCO2 and AsIII allocated more sugars to roots sequentially. Sugar accumulation in plant roots is further induced by AMF, resulting in more C skeletons to produce organic acids, which are effectively exudated into the soil to reduce AsIII uptake. Exposure to eCO2 reduced oxidative damage and this mitigation was stronger in soybean. This could be attributed to a greater reduction in photorespiration as well as a stronger antioxidant and detoxification defence systems. The grass/legume-specificity was supported by principal component analysis, which revealed that soybean was more affected by AsIII stress and more responsive to AMF and eCO2. This study provided a mechanistic understanding of the impact of AMF, eCO2 and their interaction on As-stressed grass and legume plants, allowing better practical strategies to mitigate AsIII phytotoxicity.

Impact of arbuscular mycorrhizal fungi and compost on the growth, water status, and photosynthesis of carob (Ceratonia siliqua) under drought stress and recovery

Biofertilizers have been reported to increase resistance of plants to drought. However, the effects of combination of arbuscular mycorrhizal fungi (AMF) with compost (C + AMF) on carob under drought and recovery have not been studied and remain poorly understood. The effects of C + AMF on the growth performance, physiological and biochemical traits of carob under drought and recovery was evaluated. The experiment was divided into two phases: (i) phase 1: half of the plants were well-watered (WW) and other half were subjected to drought stress (DS), and (ii) phase 2: rewatering the plants under DS (REC). Our findings showed that C + AMF promoted growth, nutrient content, and modified physiological and biochemical parameters in carob during the two phases. After recovery, water content, stomatal conductance, the maximum photochemical efficiency of PSII, photosynthetic pigments and plant uptake of mineral nutrients were significantly higher in shoots of C + AMF than in controls. Moreover, C + AMF reduced to a greater degree the accumulation of hydrogen peroxide and malondialdehyde content in C + AMF than in controls. It can be concluded that AMF combined with compost can successfully be applied as biofertilizers for improving the growth, physiological and biochemical parameters in carob during both DS and after REC.

Arbuscular mycorrhizal fungi alleviate elevated temperature and nitrogen deposition- induced warming potential by reducing soil N2O emissions in a temperate meadow

Nitrous oxide (N2O) is one of the most important greenhouse gases and has the potential to aggravate global warming. Arbuscular mycorrhizal (AM) fungi form mutualistic associations with most terrestrial plants, which can help plant nitrogen (N) uptake and have also been shown to reduce soil N2O emissions. However, the development and species community composition of AM fungi are influenced by warming and N deposition. To date, the mechanism by which warming, N deposition, and AM fungi interactively affect soil N2O emissions in the field is still poorly understood. We implemented elevated temperature and N addition treatments in a 5-year experiment in a semiarid temperate meadow to examine the impact of AM fungi on soil N2O fluxes under the treatment conditions. Both elevated temperature and N deposition and the combination of the two significantly increased soil N2O emissions. AM fungi reduced soil N2O emissions under elevated temperature and N deposition. The decrease in soil N2O emissions by AM fungi was lower under elevated temperature than N deposition. Under elevated temperature, the AM fungal decrease in soil N2O emissions was mainly determined by the abundance of the functional genes ammonia-oxidizing bacteria (AOB) and nosZ, while the AM fungal reduction in soil N2O emissions was mainly affected by soil microbial biomass carbon under N deposition. These results indicate that although AM fungi could reduce soil N2O emissions the pathway by which AM fungi regulate soil N2O emissions might vary under different global change contexts with elevated temperature or nitrogen deposition. Our results highlight the negative effect of AM fungi on soil N2O emissions under elevated temperature and N deposition and show that the influence of AM fungi on N2O emissions might be simultaneously determined by warming, N deposition and ecosystem types. The results of the study help to evaluate the potential role of AM fungi in reducing N2O emissions from grassland ecosystems in the context of future global change and provide a theoretical basis for sustainable grassland management.

Improved Salt Tolerance of Lamtoro (Leucaena leucocephala) through the Application of Indigenous Mycorrhiza

Salt stress is one of the serious abiotic stressors which limit the growth and development of important crops in agricultural lands. Arbuscular mycorrhizal fungi (AMF) have been implemented as a strategy to mitigate the adverse effects due to an impact of salt stress through the structural and physiological adjustment. This study aimed to determine a relationship between salinity levels (0, 150, 300, and 450 mM NaCl) and AMF treatments (Glomus manihotis, Glomus etunicatum, and G. manihotis + G. etunicatum) to the salt tolerance of Leucaena leucocephala seedlings in a greenhouse. Salinity reduced the plant height, biomass, and root colonization by AMF. However, the inoculation of AMF, especially the consortium, ameliorated the negative effects by stabilizing the growth performance and supporting the photosynthetic outputs through optimum nutrient and mineral absorptions. These results were indicative through a significant interaction between salinity levels and the types of AMF treatment in all parameters except in the total leaf protein and proline contents from the two-way ANOVA results. Root colonization was highly correlated with the plant height, biomass, and total carbohydrate content with a maximum contribution conferred by the AMF consortium, based on Pearson’s correlation coefficient test and PCA analysis. Our study then showed the positive impact of AMF toward salt tolerance by L. leucocephala with potential application and cultivation in salt-stressed ecosystems.

Arbuscular Mycorrhizal Fungi Increase Pb Uptake of Colonized and Non-Colonized Medicago truncatula Root and Deliver Extra Pb to Colonized Root Segment.

Arbuscular mycorrhizal (AM) fungi establish symbiosis and improve the lead (Pb) tolerance of host plants. The AM plants accumulate more Pb in roots than their non-mycorrhizal counterparts. However, the direct and long-term impact of AM fungi on plant Pb uptake has been rarely reported. In this study, AM fungus (Rhizophagus irregularis) colonized and non-colonized roots of Medicago truncatula were separated by a split-root system, and their differences in responding to Pb application were compared. The shoot biomass accumulation and transpiration were increased after R. irregularis inoculation, whereas the biomass of both colonized and non-colonized roots was decreased. Lead application in the non-colonized root compartment increased the R. irregularis colonization rate and up-regulated the relative expressions of MtPT4 and MtBCP1 in the colonized root compartments. Rhizophagus irregularis inoculation increased Pb uptake in both colonized and non-colonized roots, and R. irregularis transferred Pb to the colonized root segment. The Pb transferred through the colonized root segment had low mobility and might be sequestrated and compartmented in the root by R. irregularis. The Pb uptake of roots might follow water flow, which is facilitated by MtPIP2. The quantification of Pb transfer via the mycorrhizal pathway and the involvement of MtPIP2 deserve further study.

Exploring arbuscular mycorrhizal symbiosis in wetland plants with a focus on human impacts

Presence and functional roles of arbuscular mycorrhizal (AM) fungi in wetland environment have gained a global importance in recent past. Wetlands build a low-oxygen atmosphere, forming a completely different ecological environment for AM fungi, known more to occur in terrestrial environment. Nevertheless, as many 101 of AM fungi species, belonging to 19 genera and 9 families have been observed in the rhizosphere of wetland plants. In order to obtain oxygen, AM fungi expand the aeration system of wetland plants, store oxygen through their own vesicles, or change the structure of AM to survive. Human activities negatively affect the wetland environment, thus, reducing the population of AM fungi, while certain AM fungi species still improved the survival and development of wetland plants. AM fungi regulate different physiological activities of wetland plants in response to waterlogging stress, including an enhancement of antioxidant defense system, increased proline accumulation, improved plant growth and root morphology, responses of nutrients and aquaporins, and suppression in ethanol accumulation. The current review briefly summarized different species of wetland plants forming AM structures, the population of AM fungi inhabiting the rhizosphere of wetland plant, AM fungi-colonization of wetland plants, and the effect of AM fungi on physiological functions of wetland plants to neutralize the negative impact of waterlogging in addition to outlook of researchable issues. This review also highlighted human impacts on AM fungi of wetland plants and the impact of AM fungi on wetland environments and wetland plants.