Presence Of Arbuscular Mycorrhizal Fungi Research Articles

Arbuscular mycorrhizal fungal abundance in elevation belts of the hyperarid Atacama Desert

Arbuscular mycorrhizal (AM) fungi affect ecosystem processes improving plant tolerance in (hyper)arid/saline environments. However, there are no previous studies on the presence of AM fungi in the Atacama Desert (Northern Chile), the driest desert in the world. Here, we studied the root and rhizosphere in 111 samples of representative plants from three elevation gradients: (i) hyperarid desert (700–2000 m a.s.l.), (ii) pre-Puna (2000–3100 m a.s.l.) and (iii) Puna (3100–4500 m a.s.l.) elevation belts. Soil pH, electrical conductivity (EC), organic matter, cations and the AM colonization and fungal structures were determined. All plants showed colonization and fungal structures. Root colonization ranged from 3.5 to 87%, hyphae showed densities from 0.13 to 204 m g −1 , and spore densities between 20 and 45,500 per 100 g of soil. The highest fungal structure abundances were found in Prosopis tamarugo , Baccharis scandens , Werneria pinnatifida , Deyeuxia curvula and Festuca deserticola rhizospheres. In general, EC and cations showed strong relationship with fungal structure abundance. Here, we reported for the first time the widespread presence of AM symbiosis in all the elevation belts of the Atacama Desert, constituting a first step to understand the ecological role that AM fungi play under extreme aridity and salinity conditions.

Quantifying Nutrient Trade in the Arbuscular Mycorrhizal Symbiosis Under Extreme Weather Events Using Quantum-Dot Tagged Phosphorus

Given the current trends in climate change, extreme weather events are expected to increase in strength and frequency. Such events can impact species survival and species interactions. One of the most ubiquitous symbioses on earth is the nutrient exchange partnership between arbuscular mycorrhizal fungi and their host plants. While past work has shown that mycorrhizal fungi can help alleviate stress, it is unknown how phosphorus uptake by plants to fungi is affected by extreme weather events, such as flooding and heat waves. To test this response, we grewMedicago truncatulahost plants with or without mycorrhizal fungi and then exposed them to extreme weather treatments: increasing soil temperature by 12°C, or by flooding the plant roots for 7 days. We measured plant and fungal performance, and quantified phosphorus (P) uptake before and after extreme weather treatments using a technique in which we tagged apatite, a form of rock phosphorus, with fluorescing quantum-dots (QDs) nanoparticles. We then measured fluorescence in root and shoot tissue at harvest. We found that plants and arbuscular mycorrhizal fungi were affected by soil flooding, with plant survival, fungal colonization and QD-apatite uptake decreasing under flooded conditions. We did not see these negative effects in the heat treatment. While the presence of arbuscular mycorrhizal fungi affected plant biomass allocation, leading to an increase in shoot biomass, the symbiosis did not increase plant survival, total biomass or QD uptake in either treatment. More generally, we found host tissue contained roughly 80% more QD-apatite from the pre-treatment compared to the post-treatment nutrient injection. Future studies should focus on various plant-fungal combinations to create databases on which predictive models to extreme weather events can be constructed.

Use of arbuscular mycorrhizal fungi and phosphorus for increase in the concentration of compounds with antioxidant activity in Libidibia ferrea

The increase of the concentration of secondary compounds in medicinal plants can be influenced by the association with arbuscular mycorrhizal fungi (AMF). Pharmacological studies have shown that secondary compounds, found ing Libidibia ferrea (Mart. ex Tul.) L. P. Queiroz, confer phytotherapeutic potential to the species due to antidiabetic, antibiotic and anticancer activity. Therefore, the aim of this work was to verify if the presence of AMF associated or not with phosphate fertilization has an effect on the concentration of foliar phenolic compounds with antioxidant activity in L. ferrea seedlings. The seedlings were transferred to pots with 1.2 kg of soil with phosphate fertilization (P2O5) or not. In the roots was deposited soil-inoculum, containing 300 spores {100 spores of each AMF species: Claroideoglomus etunicatum, Gigaspora albida and Acaulospora longula Acaulospora longula. The plants were maintained in greenhouse for seven months. AMF favored an increase in shoot dry matter production, accumulation of flavonoids and greater total antioxidant activity, dispensing fertilization of the soil. The mycorrhizal inoculation associated with phosphate fertilization maximized the biosynthesis of total chlorophyll and soluble carbohydrates. AMF inoculation presents as a possible biotechnological alternative to increase antioxidant activity and foliar flavonoid production in L. ferrea seedlings, avoiding expenses with agricultural inputs, such as phosphate fertilization, making phytomass more attractive for the production of phytotherapics.

Nitrogen Uptake, Not Transfer of Carbon and Nitrogen by CMN, Explains the Effect of AMF on the Competitive Interactions Between Flaveria bidentis and Native Species

Rhizophagus intraradices, one of the common arbuscular mycorrhizal fungi (AMF) grown in the roots ofFlaveria bidentis, facilitates the invasion of this exotic plant species into China. However, it is still unknown whether nutrient transfer through the common mycorrhizal networks (CMN) between this exotic species and the native species enhances the competitive growth ofF. bidentisover the native species. To elucidate this question and the related mechanism, an isotopic labeling technique was used to test the transfer of carbon (C) and nitrogen (N) by CMN. Native species likeSetaria viridisandEclipta prostratawere selected to compete withF. bidentisin a polyvinyl chloride (PVC) box. Two competitive groups (F. bidentis-S. viridisandF. bidentis-E. prostrata), three treatments (monoculture ofF. bidentis, the mixture ofF. bidentisand the native plant, and the monoculture of the native plant), and two levels of AMF (presence or absence) were assigned. Results showed that the corrected index of relative competition intensity (CRCI) ofF. bidentisin the presence of AMF < 0 suggests that the competition facilitated the growth ofF. bidentiswith eitherS. viridisorE. prostrata. The reason was that the inoculation ofR. intra radicessignificantly increased the C and N contents ofF. bidentisin the mixtures. However, the effects ofR. intra radiceson the two native species were different: negative effect on the growth ofS. viridisand positive effect on the growth ofE. prostrata. The change of N content inS. viridisorE. prostratawas consistent with the variation of the biomass, suggesting that the N uptake explains the effects ofR. intraradiceson the competitive interactions betweenF. bidentisand the two native species. Moreover, the transfer of C and NviaAMF hyphal links did occur betweenF. bidentisand the native species. However, the transfer of C and N by the CMN was not positively related to the competitive growth ofF. bidentis.

Interaction between mycorrhizal fungi and Meloidogyne javanica on the growth and essential oil composition of basil (Ocimum basilicum)

Plant-parasitic nematodes and arbuscular mycorrhizal fungi (AMF) have been reported to alter the yield and chemical composition of basil (Ocimum basilicum) essential oil. The aim of this study was to evaluate the effectiveness of AMF to control the root-knot nematode Meloidogyne javanica in basil and to investigate the effects of nematode-AMF interactions on plant growth, phosphorus (P) absorption, and essential oil composition. The experiment was conducted under greenhouse conditions following a completely randomized 3 × 2 factorial (two fungal species and an uninoculated control × inoculated and uninoculated seedlings) arrangement with 10 replicates. Substrates were inoculated with Claroideoglomus etunicatum, Rhizophagus clarus, or no fungi (control) and sown with basil seeds. After 20 days, half of the seedlings were inoculated with 4,000 M. javanica eggs. After 60 days, the vegetative parameters, P absorption, essential oil composition, nematode population density, AMF root-colonization efficiency, and AMF spore density were determined. The presence of AMF increased the basil’s fresh weight and ability to absorb P, while reducing the M. javanica reproduction. In total, 21 compounds were identified in basil essential oil, the concentrations of which varied according to the treatments. The major components were eucalyptol, linalool, eugenol, β-elemene, trans-α-bergamotene, and τ-cadinol. Inoculation with AMF decreased the linalool levels but increased the amount of eucalyptol. Mycorrhizal plants showed increased shoot height, P uptake, and essential oil yield and a decreased nematode population density in their roots

Arbuscular mycorrhizal fungi potentially regulate N2O emissions from agricultural soils via altered expression of denitrification genes

Agricultural soils are an important source of nitrous oxide (N2O), a potent greenhouse gas involved in the destruction of the protective ozone layer that contributes to global warming. During N2O production, soil microorganisms play important driving and regulating roles. A few recent studies have revealed the potential effects of arbuscular mycorrhizal fungi (AMF), a widely distributed soil fungi, on controlling N2O emissions. However, how AMF regulate N2O production from soils remains poorly understood. To address the knowledge gap, we manipulated two independent soil environments, which were either allowed (AM) or prevented (NM) access by AMF hyphae in a microcosm experiment (n = 5). Soil physicochemical properties, N2O flux, the diversity of bacterial communities, and the abundance of key genes responsible for N2O production were assessed in both treatments over three months. Results showed that the presence of AMF significantly decreased N2O emissions from agricultural soils in the 1st month, and the abundance of key genes responsible for denitrification (nirK and nosZ) significantly decreased in AM treatments, indicating that the regulation of N2O emissions is transmitted by AMF-induced changes in the denitrification process. A structural equation model further revealed that AMF indirectly influenced N2O emissions by altering the abundance of N metabolism-related genes, rather than by altering soil chemical properties or the diversity of bacterial communities. Thus, we proposed a possible mechanism by which AMF can regulate denitrification activities and therefore N2O emissions from agricultural soils.

Status Dan Keanekaragaman Fungi Mikoriza Arbuskula di Lahan Agroforestri

Coffee is one of the leading commodities in Indonesia. These plants are usually cultivated with agroforestry systems. The agroforestry system was chosen because it can increase crop productivity. But there are still many factors that can affect productivity such as Arbuscular Mycorrhizal Fungi (AMF). This study aims to analyze the relationship between the number of spores, the percentage of colonization, and the diversity of AMF. The result showed that the highest percentage of colonization and the number of spores found in land 3. The agroforestry component affects the presence of AMF. The percentage of colonization and the number of spores from AMF is generally directly proportional. Diversity of AMF spores morphological type, among others Glomus has 9 forms, Acaulospora has 5 forms, Dentiscutata has 5 forms, Entrophospora has 4 forms, and Gigaspora has 1 form.
 Keywords: Acaulospora, Dentiscutata, Entrophospora, Gigaspora, Glomus

Novel insights into host receptors and receptor-mediated signaling that regulate arbuscular mycorrhizal symbiosis.

More than 80% of land plant species benefit from symbiotic partnerships with arbuscular mycorrhizal (AM) fungi, which assist in nutrient acquisition and enhance the ability of host plants to adapt to environmental constraints. Host-generated plasma membrane-residing receptor-like kinases and the intracellular α/β-hydrolase DWARF14-LIKE, a putative karrikin receptor, detect the presence of AM fungi before physical contact between the host and fungus. Detection induces appropriate symbiotic responses, which subsequently enables a favorable environment for AM symbiosis to occur. To prevent hyper-colonization and maintain a mutually beneficial association, the host plant precisely monitors and controls AM colonization by receptor-like kinases, such as SUPER NUMERIC NODULES. Previous studies have elucidated how host plant receptors and receptor-mediated signaling regulate AM symbiosis, but the underlying molecular mechanisms remain poorly understood. The identification of a rice CHITIN ELICITOR RECEPTOR KINASE 1 interaction partner, MYC FACTOR RECEPTOR 1, and new insights into DWARF14-LIKE receptor- and SUPER NUMERIC NODULES receptor-mediated signaling have expanded our understanding of how host plant receptors and their corresponding signals regulate AM symbiosis. This review summarizes these and other recent relevant findings. The identified receptors and/or their signaling components could be manipulated to engineer crops with improved agronomic traits by conferring the ability to precisely control AM colonization.

Climate warming negates arbuscular mycorrhizal fungal reductions in soil phosphorus leaching with tall fescue but not lucerne

Nutrient losses due to leaching from agricultural soils can be substantial but, in some cases, soil microbes such as arbuscular mycorrhizal (AM) fungi can buffer those losses. An important knowledge gap, however, is the extent to which climate change may affect AM fungal mediation of leaching via warming and drought. To investigate this, we grew lucerne (Medicago sativa) and tall fescue (Festuca arundinacea), in the presence and absence of AM fungal inoculation (Rhizophagus irregularis), under different temperature [ambient: 26 °C (aT); elevated: 30 °C (eT)] and water [well-watered: 100% soil water holding capacity (WHC); droughted: 40% WHC] treatments. After four months of plant growth, leached nutrients (PO4−, NH4+ and NO3−), plant biomass, nitrogen (N), phosphorus (P), and mycorrhizal parameters (colonization and extraradical hyphae biomass) were measured. The presence of AM fungi significantly reduced P leaching with lucerne by 46% for both temperature treatments, but P loss with tall fescue was only reduced under aT (by 48%). The negation of this benefit for tall fescue under eT was associated with a reduction in mycorrhizal root colonization, while temperature did not alter mycorrhizal root colonization of lucerne. Watering regime was not observed to influence P loss via leaching. We did not find a mycorrhizal effect on N leaching for either species; however, we found that N leaching increased under drought with lucerne and responded interactively to warming and drought with tall fescue. Overall, AM fungi significantly reduced P leaching for both species, but warming eliminated this effect for tall fescue, suggesting that warming may differentially affect P leaching depending upon plant species.

An improved clearing and staining protocol for evaluation of arbuscular mycorrhizal colonisation in darkly pigmented woody roots

Arbuscular mycorrhizal fungi (AMF) establish symbiotic interactions with the roots of vascular plants, including grapevines. Verifying AMF colonisation routinely requires establishing the presence of hyphae, arbuscules and vesicles. Clearing roots with potassium hydroxide (KOH) followed by staining with trypan blue has been used previously to visualise fungal structures, however visualisation is difficult with darkly pigmented roots, such as those of grapevines so additional steps are required to ensure clear visualisation. Three fixing and clearing processes were evaluated prior to staining with trypan blue: 1) fixing grapevine roots in 70% v/v ethanol overnight; 2) clearing by heating the roots in either 2% or 10% w/v KOH; and 3) clearing the roots in 3% v/v hydrogen peroxide for 10 min. Roots were examined under a compound light microscope for the presence of AMF. A combination of fixing grapevine roots in 70% ethanol overnight and clearing by autoclaving in 10% KOH produced the greatest enhancement in subsequent staining of grapevine roots with trypan blue overnight. The best method tested enabled the discrimination of arbuscular mycorrhizal structures in fresh roots of grapevines without the use of toxic chemical fixatives.

Employ of arbuscular mycorrhizal fungi for pharmaceuticals ibuprofen and diclofenac removal in mesocosm-scale constructed wetlands

This study investigated the effects of arbuscular mycorrhizal fungi (AMF) colonization on the growth of wetland plants (Glyceria maxima), and treatment performance in constructed wetlands (CWs) under the stress of pharmaceuticals ibuprofen (IBU) and diclofenac (DCF). Results showed that the growth of G. maxima was significantly increased by AMF colonization. AMF significantly increased the activities of antioxidant enzymes (peroxidase and superoxide dismutase) and soluble protein content in wetland plants, but the contents of malondialdehyde and O2•− were reduced. The removal efficiencies of TOC, PO43−-P, NH4+-N, and TN were increased in AMF+ treatments by 6%, 11%, 15% and 11%, respectively. AMF increased the removal efficiencies of IBU and DCF by 6–14% and 2–21%, respectively, and reduced the content of their metabolites (2-OH IBU, CA IBU and 4′-OH DCF) in the effluent. Besides, the presence of AMF increased the contents of IBU and DCF in plant roots, while decreased their transportation to shoots. AMF symbiosis decreased the contents of IBU metabolites (2-OH IBU and CA IBU) but increased the contents of DCF metabolite (4′-OH DCF) in the roots of the host plant. In conclusion, these results indicated that AMF plays a promising role in CWs for emerging pollutants removal.

KEANEKARAGAMN FUNGI MIKORIZA ARBUSKUA (FMA) LAHAN KAMPUS UNIVERSITAS LANCANG KUNING (UNILAK

Arbuscular mycorrhizal fungi (AMF) are naturally scattered and symbiotic with various tree species, AMF is able to improve plant adaptation to extreme soil conditions. About thirty-seven years Unilak, has been built in Riau Province, precisely in Rumbai Pekanbaru City. How is the existence of FMA on the developed campus land? Is the focus of this paper. Soil sampling for AMF observation refers to the modified ICRAF method. The extraction of AMF spores followed the pour and wet filter method followed by centrifugation techniques. Based on the morphological characteristics of the extracted AMF spores, it was identified to the genus level. The research series showed that the presence of AMF on the Unilak campus area contained 13 types of spores from the genus Acaulospora, Gigaspora, Glomus and Sclerocystis.

Heavy grazing disrupts positive effects of arbuscular mycorrhizae symbiosis on community productivity and stability under low and high phosphorus conditions

We quantified the potential influence of arbuscular mycorrhizal fungi (AMF) on primary productivity and community stability and tested whether the effects of AMF depend on soil phosphorus (P) availability and grazing intensity in a semiarid grassland. We manipulated the abundance of AMF and soil P availability (P addition and no P addition) under four levels of grazing intensity. The aboveground biomass of plant species, functional groups and community, as well as community temporal stability were examined under these conditions. Under no to moderate grazing, benomyl decreased the aboveground biomass in C4 grasses and forbs, but increased the aboveground biomass in C3 grasses under low P conditions; thus no obvious changes in community primary productivity were observed. These results indicated that the mycorrhizal dependency of C4 grasses and forbs is higher than that of C3 grasses under low P conditions. However, community primary productivity was greatly enhanced by benomyl due to the increased biomasses of C3 grasses and forbs under high P conditions. Under heavy grazing conditions, benomyl increased community primary productivity under both low and high P conditions. AMF presence increased the community temporal stability by promoting the compensatory effects between plant species under no to moderate grazing conditions; whereas AMF decreased the community stability by forming a parasitic symbiosis with their plant hosts under heavy grazing conditions. Our findings demonstrate that the effects of benomyl application to suppress AMF on primary productivity and community stability are strongly mediated by soil P availability and grazing intensity, which improves our understanding for the roles of AMF-plant symbiosis on ecosystem functioning in grazed systems.

Symbiotic soil fungi enhance resistance and resilience of an experimental grassland to drought and nitrogen deposition

Abstract Ecosystem stability is threatened by multiple global change factors such as drought and elevated nitrogen deposition. Yet, it is still poorly understood whether soil organisms can buffer against such perturbations. Here we focus on arbuscular mycorrhizal fungi (AMF), a common and widespread group of soil fungi. AMF form symbiotic associations with the majority of terrestrial land plants and promote a range of ecosystem services including plant production, diversity and nutrient cycling. We tested whether AMF have the ability to enhance the resistance and resilience of plant communities under soil moisture deficit (hereby drought) and nitrogen deposition. Grassland microcosms with 11 different plant species were established with and without AMF and exposed to elevated nitrogen levels and to an intermittent period of drought. Drought strongly reduced plant productivity and nitrogen cycling, but had limited effects on plant diversity. Nitrogen enrichment reduced plant diversity and increased nitrogen leaching and N2O emissions. The presence of AMF enhanced plant productivity, plant diversity and reduced nitrogen losses. AMF facilitated the resistance of plant productivity and nitrogen cycling to drought and the recovery of the plant community structure back to its pre drought state. Furthermore, AMF also mitigated the adverse effects of nitrogen enrichment on the resistance of multiple ecosystem functions to drought. Synthesis. Our work highlights the integral role of AMF for the stability of ecosystem functioning; AMF are not only able to promote resistance to harsh conditions of global change but also improve resilience by enabling plant communities to recover. These findings underline AMF's insurance capacity to buffer ecosystems against global change.

Increasing the Sustainability of Maize Grain Production by Using Arbuscular Mycorrhizal Fungi Does Not Affect the Rumen of Dairy Cattle (Bos taurus) and Buffalo (Bubalus bubalis).

New approaches are needed to improve the sustainability of feed production and utilization by ruminants. Promising approaches include increased use of buffaloes for more sustainable milk production, and arbuscular mycorrhizal fungi (AMF) to reduce crop production input needs. However, studies assessing the effect of crops grown in the presence of AMF on rumen microbial utilization are limited. Based on current knowledge, we hypothesized that maize grain grown on AMF-inoculated soil affected ruminal fermentation and microbiota, and that this effect differed between buffalo and cattle. A dietary cross-over study (four weeks per diet) was conducted using rumen-cannulated cattle (n = 5) and buffalo (n = 6) to assess the effect of maize grain (3.9% (w/v) of diet) grown on soil with or without AMF (15 kg/ha) on ruminal fermentation and microbiota. Production of maize on AMF-treated soil did not affect any of the assessed ruminal fermentation parameters, microbial concentrations, or prokaryotic community composition (using prokaryotic 16S rRNA gene sequence analysis). In contrast, host type had numerous effects. Protozoal counts, lactate, total VFA and isobutyrate, were significantly higher in buffaloes compared to cattle. Conversely, butyrate was significantly lower in buffaloes than in cattle. Host type explained 9.3% of the total variation in prokaryotic community composition, and relative abundance of nine amplicon sequence variants significantly differed between host types. These findings indicate that AMF treatment of maize crops has no detrimental impact on the value of the resulting maize grains as a ruminant feed, and provides additional insight into rumen-based differences between cattle and buffalo.

Root growth and presence of Rhizophagus irregularis distinctly alter substrate hydraulic properties in a model system with Medicago truncatula

AimWe investigated how substrate hydraulic properties respond to the presence of arbuscular mycorrhizal fungi (AMF) in root-containing and root-free substrate zones in a Medicago truncatula-Rhizophagus irregularis model system.MethodsBefore planting, two compartments constructed from standard soil sampling cores (250 cm3) were implanted into non-mycorrhizal and mycorrhizal pots containing a sand-zeolite-soil mix. One compartment allowed root penetration (1 mm mesh cover) and the other only hyphal ingrowth (42 μm mesh cover). After eight weeks of growth under maintenance of moist conditions, the cores were subjected to water retention measurements. Additionally, we measured water retention of bare substrates before and after drying events to check for successful maintenance of moist conditions in pots.ResultsDrying of bare substrates decreased water retention, but planting at least sustained it. The parameters of water retention models responded linearly to root morphological traits across mycorrhizal and non-mycorrhizal substrates. Hyphae-only colonization comparatively affected the course of water retention in ways that suggest increased pore space heterogeneity while maintaining water storage capacity of substrates.ConclusionsHence, water contents corresponded to different substrate matric potentials in non-mycorrhizal and mycorrhizal pots. We conclude that changes to water retention in AMF colonized substrates can contribute to a widely observed phenomenon, i.e. that mycorrhizal plants differ in their moisture stress response from non-mycorrhizal plants.

Orchard management practices affect arbuscular mycorrhizal fungal root colonisation of almond

ABSTRACT Arbuscular mycorrhizal fungi (AMF) are mutualistic fungi that play important roles in plant nutrition and soil ecosystem functions. While AMF are known to benefit diverse host plants under a range of conditions, little is known about their presence in commercial almond orchards and how frequently used management practices regulate AMF root colonisation. A large-scale survey of almond orchards in the Central Valley of California was conducted to determine the extent of mycorrhizal associations with roots and the impact of orchard management practices and soil properties on AMF root colonisation rates. The roots in all orchards were colonised, with an overall average rate of 64.4%. Organically managed orchards had higher AMF root colonisation rates (73.2%) as compared with conventionally managed orchards (62.1%), primarily due to the presence of soil vegetative cover rather than organic matter inputs. Choice of rootstock and fumigation had only marginal effects while inoculation at planting increased AMF root colonisation of young trees by 27% compared to non-inoculated control. These results highlighted the ubiquitous presence of AMF in commercial almond orchards and significant interacting influences of common management practices on AMF root colonisation under field conditions. Further research into the functional implications of mycorrhizal associations in these orchards will help guide the development of management practices that increase AMF abundance and root colonisation to improve the sustainability of this rapidly expanding industry.

Influence of Funneliformis mosseae enhanced with titanium dioxide nanoparticles (TiO2NPs) on Phaseolus vulgaris L. under salinity stress.

The Arbuscular mycorrhizal fungi (AMF) (Funneliformis mosseae), are the most widely distributed symbiont assisting plants to overcome counteractive environmental conditions. In order to improve the sustainability and the activity of AMF, the use of nanotechnology was important. The main objective of this study was to investigate the effect of titanium dioxide nanoparticles (TiO2NPs) on the activity of AMF in common bean roots as well as its activity under salinity stress using morphological and molecular methods. The activity of AMF colonization has increased in the presence of TiO2NPs especially for arbuscule activity (A%), which increased three times with the presence of TiO2NPs. The improvement rate of Funneliformis mosseae on plant growth increased from 180% to 224% of control at the lowest level of salinity and increased from 48% to 130% at higher salinity level, respectively. The AMF dependencies for plant dry biomass increased in the presence of TiO2NPs from 277% in the absence of salinity to 465 and 883% % at low and high salinity levels, respectively. The presence of AMF co-inoculated with TiO2NPs resulted in increasing the salinity tolerance of plants at all levels and reached 110% at salinity level of 100 mM NaCl. Quantitative colonization methods showed that the molecular intensity ratio and the relative density of paired inocula AMF Nest (NS) or chitin synthases gene (Chs) with TiO2NPs were higher significantly P.>0.05 than single inoculants of AMF gene in roots under the presence or the absence of salinity by about two folds and about 40%. Hence, the positive effect of TiO2NPs was confined to its effect on AMF not on bean plants itself.

Arbuscular mycorrhizal fungi mitigate Fe deficiency symptoms in sorghum through phytosiderophore-mediated Fe mobilization and restoration of redox status.

Sustainable management of iron (Fe) deficiency through the microbial association is highly desirable to ensure crop yield. This study elucidates whether and how arbuscular mycorrhizal fungi (AMF) ameliorate Fe deficiency symptoms in sorghum. AMF inoculation showed a significant improvement in plant biomass, chlorophyll score, Fv/Fm (quantum efficiency of photosystem II), and Pi_ABS (photosynthesis performance index), suggesting its potentiality to diminish Fe deficiency symptoms in sorghum. This AMF-driven prevention of Fe deficiency was further supported by the improvement of biochemical stress indicators, such as cell death, electrolyte leakage, hydrogen peroxide, and superoxide anion. In this study, AMF showed a significant increase in phytosiderophore (PS) release as well as Fe and S concentrations in sorghum under Fe deficiency. Quantitative real-time PCR analysis demonstrated the consistent upregulation of SbDMAS2 (deoxymugineic acid synthase 2), SbNAS2 (nicotianamine synthase 2), and SbYS1 (Fe-phytosiderophore transporter yellow stripe) in roots due to AMF with Fe deficiency. It suggests that the enhancement of Fe due to AMF is related to the mobilization of Fe(III)-PS in the rhizosphere supported by the long-distance transport of Fe by SbYS1 transporter in sorghum. Our study further showed that the elevation of S mainly in the presence of AMF possibly enhances theS-containing antioxidant metabolites (Met, Cys, and GSH) as well as enzymes (CAT, SOD, and GR) to counteract H2O2 and O2- forthe restoration of redox status in Fe-deprived sorghum. Moreover, S possibly participates in Strategy II responses revealing its crucial role as a signaling molecule for Fe homeostasis in sorghum.

Different wheat cultivars exhibit variable responses to inoculation with arbuscular mycorrhizal fungi from organic and conventional farms.

The present study aimed to investigate the effects of arbuscular mycorrhizal (AM) fungal communities originating from organic and conventional agriculture on wheat growth and yield. Six different spring wheat cultivars released in different years in north and central European countries were considered. We hypothesised that AM fungal inoculum collected from organic agricultural fields would elicit a greater positive growth response than inoculum collected from conventional agricultural fields; and that older cultivars, which were developed under conditions of low fertilizer input, would exhibit overall greater growth responses to the presence of AM fungi, compared with more recent cultivars, and that AM fungal inoculum from conventional fields might have the most beneficial effect on the growth and yield of recent cultivars. The results showed that the overall effects on the growth and yield of spring wheat grown with organic and conventional AM fungal inocula did not differ greatly. However, the inoculation growth response, showing the difference of the effects of organic and conventional inocula, varied between particular wheat cultivars. Inoculation growth response of the cultivar Pikker (released in 1959) was the most positive, while that of the cultivar Arabella (released in 2012) was the most negative. The use of AM fungal inoculum from organic fields resulted in slightly taller plant individuals. Pikker showed relatively higher yield and stronger growth when the organic AM fungal inoculum was used. Arabella exhibited relatively lower yield and weaker growth when the organic inoculum was used. Whether the positive response of Pikker to Estonian organic inoculation reflects adaptation to the locally occurring AM fungal community needs to be established by further studies of the communities of AM fungi colonizing wheat roots.