Arbuscular Mycorrhizal Fungi Inoculation Research Articles

Arbuscular mycorrhizal fungi trigger danger-associated peptide signaling and inhibit carbon-phosphorus exchange with nonhost plants.

In soil, arbuscular mycorrhizal fungi (AMF) meet the roots of both host and presumed nonhost plants, but the interactional mechanisms of AMF with and functional relevance for nonhost plants is little known. Here we show AMF can colonize an individually grown nonhost plant, Arabidopsis thaliana, and suppress the growth of Arabidopsis and two nonhost Brassica crops. This inhibitory effect increased with increasing AMF inoculum density, and was independent of AMF species or nutrient availability. 13 C isotope labeling and physiological analyses revealed no significant carbon-phosphorus exchange between Arabidopsis and AMF, indicating a lack of nutritional function in this interaction. AMF colonization activated the danger-associated peptide Pep-PEPR signaling pathway, and caused clear defense responses in Arabidopsis. The impairment of Pep-PEPR signaling in nonhost plants greatly compromised AMF-triggered defensive responses and photosynthesis suppression, leading to higher colonization rates and reduced growth suppression upon AMF inoculation. Pretreatment with Pep peptide decreased AMF colonization, and largely substituted for AMF-induced growth suppression in nonhosts, confirming that the Pep-PEPR pathway is a key participant in resistance to AMF colonization and in mediating growth suppression of nonhost plants. This work greatly increases our knowledge about the functional relevance of AMF and their mechanisms of interactions with nonhost plants.

Arbuscular mycorrhizal fungus Rhizophagus irregularis alleviates drought stress in soybean with overexpressing the GmSPL9d gene by promoting photosynthetic apparatus and regulating the antioxidant system

Drought is the most destructive abiotic stress and negatively affects crop growth and productivity. Modern breeding efforts have produced numerous cultivars with distinct genetic traits that improve crop growth and drought stress tolerance. Arbuscular mycorrhizal fungi (AMF) can enhance drought tolerance in soybean plants by directly providing nutrients to plants, promoting photosynthesis, or influencing interspecific plant interactions in natural communities. However, the interactions between AMF and wild and transgenic soybean genotypes remain unclear. Therefore, in the present study, we evaluated the effect of arbuscular mycorrhizal fungi on the growth performance of drought-stressed transgenic soybean lines (ZXOE-11 and ZXOE-13) overexpressing GmSPL9d gene and their wild soybean Tianlong 1 (TL1) at the seedling stage (45 d after sowing). The results showed that colonization of wild and transgenic soybean with Rhizophagus irregularis significantly decreased the adverse effects of drought on plant growth. AMF inoculation significantly increased plant biomass, root activity, chlorophyll metabolism, photosynthesis, and chlorophyll fluorescence in wild-type and transgenic plants under both control and drought stress conditions. Drought causes the production of ROS, such as hydrogen peroxide, which enhances MDA, thereby decreasing the membrane stability index (MSI). However, AMF-inoculated plants exhibited decreased ROS accumulation and increased MSI. Moreover, AMF treatment significantly improved osmolyte, nitrogen, and nitrate reductase activity under control and drought conditions, which increased the relative water content. Furthermore, AMF treatment enhanced the antioxidant systems of drought-stressed plants by increasing the activities of peroxidase, superoxide dismutase, catalase, and ascorbate peroxidase. AMF improved the growth performance, photosynthesis, and antioxidant activity of transgenic plants under drought stress conditions. The present findings indicate that the AMF contribution to soybean seedling drought tolerance was more significant for the transgenic plants than for the wild plants under drought conditions. The current findings emphasize the possibility of growth and photosynthetic variation in the degree of AMF-associated drought resistance in soybean plants. Our findings suggest that future crop breeding challenges include developing cultivars for sustainable production and maximizing crop cultivar and fungal species (AMF) combinations in drought-stressed regions.

Ameliorating the drought stress tolerance of a susceptible soybean cultivar, MAUS 2 through dual inoculation with selected rhizobia and AM fungus

BackgroundDrought stress is currently the primary abiotic stress factor for crop loss worldwide. Although drought stress reduces the crop yield significantly, species and genotypes differ in their stress response; some tolerate the stress effect while others not. In several systems, it has been shown that, some of the beneficial soil microbes ameliorate the stress effect and thereby, minimizing yield losses under stress conditions. Realizing the importance of beneficial soil microbes, a field experiment was conducted to study the effect of selected microbial inoculants namely, N-fixing bacteria, Bradyrhizobium liaoningense and P-supplying arbuscular mycorrhizal fungus, Ambispora leptoticha on growth and performance of a drought susceptible and high yielding soybean cultivar, MAUS 2 under drought condition.ResultsDrought stress imposed during flowering and pod filling stages showed that, dual inoculation consisting of B. liaoningense and A. leptoticha improved the physiological and biometric characteristics including nutrient uptake and yield under drought conditions. Inoculated plants showed an increased number of pods and pod weight per plant by 19% and 34% respectively, while the number of seeds and seed weight per plant increased by 17% and 32% respectively over un-inoculated plants under drought stress condition. Further, the inoculated plants showed higher chlorophyll and osmolyte content, higher detoxifying enzyme activity, and higher cell viability because of less membrane damage compared to un-inoculated plants under stress condition. In addition, they also showed higher water use efficiency coupled with more nutrients accumulation besides exhibiting higher load of beneficial microbes.ConclusionDual inoculation of soybean plants with beneficial microbes would alleviate the drought stress effects, thereby allowing normal plants’ growth under stress condition. The study therefore, infers that AM fungal and rhizobia inoculation seems to be necessary when soybean is to be cultivated under drought or water limiting conditions.

Pioneer Tree Bellucia imperialis (Melastomataceae) from Central Amazon with Seedlings Highly Dependent on Arbuscular Mycorrhizal Fungi.

Bellucia imperialis is one of the most abundant pioneer tree species in anthropized areas of the Central Amazon, and has ecological importance for the environmental resilience of phosphorus (P)-depleted areas. Thus, we investigated whether B. imperialis depends on symbiosis with arbuscular mycorrhizal fungi (AMF) to grow and establish under the edaphic stresses of low nutrient content and low surface moisture retention capacity of the substrate. We tried three AMF inoculation treatments: (1) CON-no mycorrhizae; (2) MIX-with AMF from pure collection cultures, and (3) NAT-with native AMF, combined with five doses of P via a nutrient solution. All CON treatment seedlings died without AMF, showing the high mycorrhizal dependence of B. imperialis. Increasing P doses significantly decreased the leaf area and shoot and root biomass growth for both the NAT and MIX treatments. Increasing P doses did not affect spore number or mycorrhizal colonization, but decreased the diversity of AMF communities. Some species of the AMF community showed plasticity, enabling them to withstand shortages of and excess P. B. imperialis was shown to be sensitive to excess P, promiscuous, dependent on AMF, and tolerant of scarce nutritional resources, highlighting the need to inoculate seedlings to reforest impacted areas.

Plant propagation Litsea garciae Vidal. with shoot cutting technique inoculated with arbuscular mycorrhizal fungi

Litsea garciae Vidal. (engkala, kalangkala) is a fruit-producing plant useful as a potential medicinal plant and food. The availability of seedlings is a must if their potential is to be developed. The study aimed to evaluate the formation and growth of roots and shoots of L. garciae shoot cuttings in response to growth regulators and arbuscular mycorrhizal fungi (AMF) inoculation. The study used a factorial experiment with a completely randomized design. The treatments tested were growth regulators (without and with rootone-F) and AMF inoculation (without and with AMF). The shoot cuttings were planted in a mixture of cocopeat and husk charcoal (2:1 v/v) and placed in a propagation box in a screen house for 12 weeks. The live percentage, the percentage of callus cuttings, the percentage of rooted cuttings, and the percentage of cuttings sprouting all shoot cuttings planted reached 100%. The interaction between rootone-F and AMF had no significant effect on initiating root and shoot growth. However, cuttings treated without or with rootone-F showed a positive response to AMF inoculation, particularly in primary root formation and secondary root count. The secondary roots’ length and wet and dry weights of the cuttings with rootone-F were significantly lower than those without rootone-F.

Arbuscular mycorrhizal fungi reduce ammonia emissions under different land-use types in agro-pastoral areas

Ammonia (NH3) emissions, the most important nitrogen (N) loss, always induce a series of environmental problems such as increased the frequency of regional haze pollution, accelerated N deposition, and N eutrophication. Arbuscular mycorrhizal (AM) fungi play key roles in N cycling. However, whether AM fungi can alleviate N losses by reducing NH3 emissions is still unclear. The potential and mechanism by which AM fungi reduce NH3 emissions in five land-use types (grazed grassland, mowed grassland, fenced grassland, artificial alfalfa grassland, and cropland) were explored in this study. The results showed that AM fungal inoculation significantly reduced NH3 emissions and the mycorrhizal responses of NH3 emissions were determined by land-use type. Structural equation modeling (SEM) showed that AM fungi and land-use type directly affected NH3 emissions. In addition, the reduction in NH3 emissions was largely driven by the decline in soil NH4+-N and pH and the increase the abundances of ammonia-oxidizing archaea (AOA) and bacteria (AOB), urease activity and plant N content induced by AM fungal inoculation and land-use type. The present results highlight that reducing the negative influence of agricultural intensification caused by land-use type changes on AM fungi should be considered to reduce N losses in agriculture and grassland ecosystems.

Growth and production of soybean on different inoculant sources of arbuscular mycorrhizal fungi and water saturation periods

Production expansion to suboptimal areas such as tidal land through the application of integrated land management technology is an effort to increase soybean production in Indonesia. The study aimed to evaluate the morphophysiological response of soybean treated with arbuscular mycorrhizal fungi (AMF) inoculation and duration of water saturation in tidal land. The study was conducted in April-October 2021 in the plastic house of the Research Field of the Faculty of Agriculture, Sriwijaya University, Palembang. The experiment used a randomized complete block design with two factors and 3 replications. The first factor was the source of AMF propagations (without inoculations, corn inoculants, soybean inoculants, sugarcane inoculants, and soybean-sugarcane inoculants). The second factor was the water saturation periods (0, 2, and 4 months since planting), so there are 15 treatments. The results showed that the interaction between the inoculant sources and the duration of water saturation had no significant effect on all parameters. The inoculant propagated in the media of sugarcane produced the highest effect as compared to other treatments. The water saturation for 2 or 4 months since planting gave soybean plants a better morphophysiological response than conventional cultivation.
 Keywords: AMF inoculants; morphophysiology; saturated soil culture; soybean

Impact of Water Shortage on Soil and Plant Attributes in the Presence of Arbuscular Mycorrhizal Fungi from a Harsh Environment.

Arbuscular mycorrhizal fungi (AMF) play a crucial role in plant health due to their ability to improve tolerance to biotic and abiotic stresses. Our aim was to evaluate the effectiveness of a pool of native AMF from a harsh environment on plant performance and changes in soil attributes under different levels of drought. An experiment using maize was established, varying the soil water content to simulate severe drought (30% of the water-holding capacity [WHC]), moderate (50% of the WHC) and no drought (80% of the WHC, control treatment). Soil and plant attributes were measured (enzyme activity, microbial biomass, AMF root colonisation and plant biomass and nutrient uptake). There was a two-fold increase in plant biomass under moderate drought when compared to no drought treatment, but there was no difference in nutrient uptake. Under severe drought, there were the highest enzyme activities related to phosphorus (P) cycling and P microbial biomass, indicating higher P microbial immobilization. The increase in AMF root colonisation was observed in plants under moderate and no drought. Our findings demonstrated that the better use of the AMF inoculum varied according to drought levels, with better performance under moderate drought due to the increase in plant biomass.

Arbuscular Mycorrhizal Fungi Induce Changes of Photosynthesis-Related Parameters in Virus Infected Grapevine.

The negative effects of viruses and the positive effects of arbuscular mycorrhizal fungi (AMF) on grapevine performance are well reported, in contrast to the knowledge about their interactive effects in perennial plants, e.g., in grapevine. To elucidate the physiological consequences of grapevine-AMF-virus interactions, two different AMF inoculum (Rhizophagus irregularis and 'Mix AMF') were used on grapevine infected with grapevine rupestris stem pitting virus, grapevine leafroll associated virus 3 and/or grapevine pinot gris virus. Net photosynthesis rate (AN), leaf transpiration (E), intercellular CO2 concentration (Ci) and conductance to H2O (gs) were measured at three time points during one growing season. Furthermore, quantum efficiency in light (ΦPSII) and electron transport rate (ETR) were surveyed in leaves of different maturity, old (basal), mature (middle) and young (apical) leaf. Lastly, pigment concentration and growth parameters were analysed. Virus induced changes in grapevine were minimal in this early infection stage. However, the AMF induced changes of grapevine facing biotic stress were most evident in higher net photosynthesis rate, conductance to H2O, chlorophyll a concentration, total carotenoid concentration and dry matter content. The AMF presence in the grapevine roots seem to prevail over virus infection, with Rhizophagus irregularis inducing greater photosynthesis changes in solitary form rather than mixture. This study shows that AMF can be beneficial for grapevine facing viral infection, in the context of functional physiology.

Response of Sagebrush Steppe Grass Species to AMF Inoculum Sources and Biochar.

The sagebrush steppe has presented increasing levels of degradation. The addition of arbuscular mycorrhizal fungi (AMF) and biochar have been suggested to restore ecosystems. However, little is known about their effects on sagebrush steppe plants. We tested three sources of AMF inoculum: soil from a disturbed site (Inoculum A), soil from an undisturbed site (Inoculum B), and commercial inoculum (Inoculum C), all with and without biochar, to test if they could mediate growth of Pseudoroegneria spicata (native perennial), Taeniatherum caput-medusae (early seral; exotic annual) and Ventenata dubia (early seral; exotic annual) under greenhouse conditions. We measured AMF colonization and biomass. We hypothesized that the plant species would be differently affected by the inoculum types. The colonization of T. caput-medusae and V. dubia was greatest when inoculated with Inoculum A (38.8% and 19.6%). In contrast, the colonization of P. spicata was greatest with Inoculum B and Inoculum C (32.1% and 32.2). Biochar decreased biomass production but increased colonization with Inoculum A for P. spicata and V. dubia and with Inoculum C for T. caput-medusae. This study reveals the response of early and late seral sagebrush steppe grass species to contrasting sources of AMF and suggests that late seral plant species respond better to late seral inocula.

Efektivitas Inokulum Tunggal dan Konsorsium Fungi Mikoriza Arbuskula pada Pembibitan Tanaman Indigofera zollingeriana

Arbuscular mycorrhizal fungi (AMF) are potential biofertilizers for plants. The succeed and quality of AMF inoculation is related to the type of AMF and plants. This study aimed to find the most effective AMF species in Indigofera zollingeriana nurseries. This experiment study was designed using a completely randomized design with six treatments and five replications based on different types of AMF in single and consortium forms. Treatment details include: IFMIX (consortium: a mixture of five types of AMF), IFTE (Glomus etinucatum), IFTM (Glomus manihotis), IFTA (Acaulospora tuberculata), IFTG (Gigaspora margarita), IFTS Glomus sp. Data were analyzed using Analysis of Variance (ANOVA) and Duncan's Multiple Range Test. Based on the results of variance, AMF inoculation at Indigofera zollingeriana nurseries in a single form (IFTE, IFTM, IFTA, IFTG, and IFTS) resulted in effectiveness that was not significantly different with the consortium FMA inoculation (IFMIX) against AMF colonization, plant height, stem diameter, fresh and dry biomass of plants. Inoculation of inoculums in a single IFTE form resulted in a higher colonization value (p<0.05) than single inoculums IFTA and IFTM. It can be concluded that inoculation of a single AMF (Glomus etinucatum, Glomus manihotis, Acaulospora tuberculata, Gigaspora margarita, Glomus sp.) against AMF consortium produced the same symbiotic effectiveness on root colonization, morphological response and plant biomass production level in Indigofera zollingeriana nurseries. The root colonization rate of a single IFTE inoculum was better than a single inoculum of IFTA and IFTM.

Zn Fertilizer and Mycorrhizal Inoculation Effect on Bread Wheat Cultivar Grown under Water Deficit.

During drought stress, many enzymes are inactivated in plants due to Zn deficiency. Zn application and arbuscular mycorrhiza fungi (AMF)-wheat symbiosis reportedly improve the tolerance of plants to drought stress. This study was done to investigate the effect of Zn and AMF on plant growth, yield attributes, relative water content (RWC), harvest index (HI), photosynthetic activity, solute accumulation, glycine betaine (GB) accumulation, antioxidant activities [(catalase (CAT) and superoxide dismutase (SOD)], and ionic attributes in a bread wheat cultivar (SST806) under drought-stress in plants grown under greenhouse conditions. Zn application and AMF inoculation, separately and combined, enhanced all plant growth parameters and yield. Root dry weight (RDW) was increased by 25, 30, and 46% for these three treatments, respectively, under drought conditions compared to the control treatment. Overall, Zn application, AMF inoculation, and their combination increased protein content, RWC, and harvest index (HI) under drought stress. However, AMF inoculation improved proline content more than Zn application under the same conditions. Regarding GB accumulation, AMF, Zn, and the combination of Zn and AMF increased GB under drought compared to well-watered conditions by 31.71, 10.36, and 70.70%, respectively. For the antioxidant defense, AMF inoculation and Zn application improved SOD and CAT activity by 58 and 56%, respectively. This study showed that Zn and/or AMF increased antioxidant levels and ionic attributes under abiotic stress.

Priming effects of nZVI on carbon sequestration and iron uptake are positively mediated by AM fungus in semiarid agricultural soils

We investigated the priming effect of nanoscale zero-valent iron (nZVI) on carbon sink and iron uptake, and the possible mediation by AMF (arbuscular mycorrhizal fungi, Funneliformis mosseae) in semiarid agricultural soils. Maize seed dressings comprised of three nZVI concentrations of 0, 1, 2 g·kg−1 and was tested with and without AMF inoculation under high and low soil moistures, respectively. The ICP-OES observations indicated that both low dose of nZVI (1 g·kg−1) and high dose of nZVI (2 g·kg−1) significantly increased the iron concentrations in roots (L: 54.5–109.8 %; H: 119.1–245.4 %) and shoots (L: 40.8–78.9 %; H: 81.1–99.4 %). Importantly, the absorption and translocation rate of iron were substantially improved by AMF inoculation under the low-dose nZVI. Yet, the excess nanoparticles as a stress were efficiently relieved by rhizosphere hyphae, and the iron concentration in leaves and stems can maintain as high as about 300 mg·kg−1 while the iron translocation efficiency was reduced. Moreover, next-generation sequencing confirmed that appropriate amount of nZVI clearly improved the rhizosphere colonization of Funneliformis mosseae (p < 0.001) and the development of soil fungal community. Soil observations further showed that the hyphae development and GRSP (glomalin-related soil protein) secretion were significantly promoted (p < 0.05), with the increased R0.25 (< 0.25 mm) by 35.97–41.16 %. As a return, AMF and host plant turned to input more organic matter into soils for microbial growth and Fe uptake, and such interactions became more pronounced under drought stress. In contrast, high dose of nZVI (2 g·kg−1) tended to agglomerate on the surface of hyphae and spores, causing severe deformation and inactivation of AMF symbionts. Therefore, the priming effects of nZVI on carbon sequestration and Fe uptake in agricultural soils were positively mediated by AMF via the feedback loop of the plant-soil-microbe system for enhanced adaptation to global climate change.

AMF Inoculation Alleviates Molybdenum Toxicity to Maize by Protecting Leaf Performance.

The use of arbuscular mycorrhizal fungi (AMF) is a vital strategy for enhancing the phytoremediation of heavy metals. However, the role of AMF under molybdenum (Mo) stress is elusive. A pot culture experiment was conducted to explore the effects of AMF (Claroideoglomus etunicatum and Rhizophagus intraradices) inoculation on the uptake and transport of Mo and the physiological growth of maize plants under different levels of Mo addition (0, 100, 1000, and 2000 mg/kg). AMF inoculation significantly increased the biomass of maize plants, and the mycorrhizal dependency reached 222% at the Mo addition level of 1000 mg/kg. Additionally, AMF inoculation could induce different growth allocation strategies in response to Mo stress. Inoculation significantly reduced Mo transport, and the active accumulation of Mo in the roots reached 80% after inoculation at the high Mo concentration of 2000 mg/kg. In addition to enhancing the net photosynthetic and pigment content, inoculation also increased the biomass by enhancing the uptake of nutrients, including P, K, Zn, and Cu, to resist Mo stress. In conclusion, C. etunicatum and R. intraradices were tolerant to the Mo stress and could alleviate the Mo-induced phytotoxicity by regulating the allocation of Mo in plants and improving photosynthetic leaf pigment contents and the uptake of nutrition. Compared with C. etunicatum, R. intraradices showed a stronger tolerance to Mo, which was manifested by a stronger inhibition of Mo transport and a higher uptake of nutrient elements. Accordingly, AMF show potential for the bioremediation of Mo-polluted soil.

The Effect of Mycorrhiza Fungi and Various Mineral Fertilizer Levels on the Growth, Yield, and Nutritional Value of Sweet Pepper (Capsicum annuum L.)

Mycorrhizal fungi can increase the effectiveness of a mineral fertilizer top dressing, positively affecting sweet pepper yield and quality. For this reason, an experiment was carried out between 2014 and 2016 to study the effect of top dressing doses and the inoculation of the root system with mycorrhizal fungi on the growth and yield of sweet pepper and the content of nutrients and macro- and microelements in the fruits. Root inoculation with Arbuscular Mycorrhizal Fungi (AMF) and mineral fertilizer doses were used as experimental factors with the following combinations: (1) mycorrhization: control (without AMF); AMF applied to the plant root zone during seedling production; AMF applied to the plant root zone after seedlings were transferred to pots; (2) top dressing doses: basic dose (100%); 50% of the basic dose; 25% of the basic dose. The sweet pepper fruits were harvested during physiological maturity. AMF inoculation of the root zone resulted in high sweet pepper yields of good quality. In particular, mycorrhizal fungi applied to the root system during seedling production positively affected the pepper yield and biometric characteristics, with fruits of the thickest pericarp and the largest mass. In the experimental units with AMF, the reduction in the top dressing fertilizer dose by 50% and 75% did not cause a statistically significant decrease in the yield of peppers and did not result in a deterioration of the biometric characteristics of the plants and fruits or a reduction in the biological value of the fruits. Despite the reduction in top dressing dose by 50% and 75%, AMF contributed to the accumulation of similar amounts of phosphorus in the sweet pepper fruits. The top dressing dose of 50% applied during seedling production to the experimental units with mycorrhizal fungi resulted in a significant increase in the content of potassium, calcium, and magnesium. A significant increase in the amount of sodium in the fruits was noted in the experimental units with mycorrhizal fungi applied to the roots when the seedlings were transferred to pots. To summarize, the application of mycorrhizal fungi to the pepper root zone during seedling production is recommended because it has a positive effect on the yield and its quality. In the unit with mycorrhiza, a lower dose of mineral fertilizers did not result in a significant decrease in the yield of pepper fruits.

Kualitas Fungi Mikoriza Arbuskula (FMA) yang Diproduksi dengan Teknik Fortifikasi dan Fertigasi Berbeda pada Pertumbuhan Indigofera zollingeriana

Arbuscular mycorrhizal fungi (AMF) is a fungus that has a symbiotic impact on the plant at the root system level. The research objective was to evaluate the growth of Indigofera zollingeriana produced from inoculation of AMF under different fortification and fertigation techniques at the field scale. A completely randomized design with six treatments and five replication were applied for the study. The treatments were: FD1000, FD2000, FD3000 (AMF fortified with 1000, 2000, and 3000 ppm of AB mix at flat fertigation), FB1000, FB2000, and FB3000 (AMF fortified with 1000, 2000, 3000 ppm of AB mix at graded fertigation). The result shows that the AMF colonization level at the root of was similar (P&gt;0.05) to the upper value of colonization (80.00‒99.00%). The entire products of AMF have similar favorable symbiotic effects on the plant with major growth traits (plant high, stem diameter, number of branches and twigs). A fortification of 2000 ppm of AB mix under graded fertigation technique has produced AMF that significantly (P&lt;0.05) increased the number of leaves with higher green color level (7.5GY 4/6) compared with other treatments. In conclusion, the AMF produced by different fortification and fertigation techniques at the field scale has a similar result on root colonization effectivity and growth performance of I. zollingeriana. In addition, the AMF produced by 2000 ppm of AB mix with graded fertigation technique effectively increased the number of leaves with higher green color intensity. &#x0D; &#x0D; Keywords: AMF, arbuscular mycorrhizal fungi quality, fertigation, fortification, Indigofera zollingeriana

Field inoculation by arbuscular mycorrhizal fungi with contrasting life-history strategies differently affects tomato nutrient uptake and residue decomposition dynamics

PurposePlant microbial biostimulants, such as arbuscular mycorrhizal fungi (AMF), enhance nutrient concentration in fruits, including tomato. However, field studies on tomato AMF inoculation are scarce. AMF species belonging to Gigasporaceae and Glomeraceae families known to vary in life-history strategies may determine differential effects on plant nutrient benefits and residue decomposition. Despite this, the effect of different life-history strategies on nutrient acquisition of tomato fruits has not been investigated yet.MethodsWe studied the effect of inoculation of two tomato varieties with four AMF species belonging to Glomeraceae and Gigasporaceae. Fungal colonization, yield, fruit nutrient concentration, litter decomposition, and bacterial and fungal abundances in soil were assessed in the field under organic agriculture.ResultsOverall Gigasporaceae promoted the concentration of nutrients in tomato fruits compared to Glomeraceae. A variability in AM fungal colonization and fruit nutrient concentration was detected within Glomeraceae. Scutellospora pellucida increased the yield (+ 27%) of var. Rio Grande with respect to Gigaspora gigantea. In var. Rio Grande, inoculation with Funneliformis mosseae did not change litter decomposition as compared to non-inoculated controls, whereas it was lower than in Sclerocystis sinuosa and Gigasporaceae species, which showed the highest decomposition rates. AMF inoculation promoted soil total bacterial and fungal abundance and fungal:bacterial (F:B) ratio compared to controls, and members of Gigasporaceae had the highest F:B ratio.ConclusionThese findings pointed at the inclusion of AM fungal life-history strategy within the selection criteria for the development of biofertilizers able to enhance the nutritional value of vegetables under organic farming systems.

Some physio-biochemical traits of sunflower (&lt;em&gt;Helianthus annuus&lt;/em&gt; L.) as affected by arbuscular mycorrhizal fungi inoculation under different irrigation treatments

Plant-arbuscular mycorrhizal (AM) fungi association is one of the oldest symbiotic relationships between organisms. This relationship may be more important under stress conditions such as drought and can help the host plant tolerate drought. This study was conducted in 2016 and 2017 at the Agricultural Research Farm of Razi University, Kermanshah, Iran to evaluate the effect of AM fungi (AMF) inoculation (with either Funneliformis mosseae or Rhizophagus intraradices) on some physio-biochemical traits of three sunflower cultivars under different soil irrigation treatments (severe water deficit stress, mild water deficit stress and well-watered). In both years, water deficit conditions significantly reduced leaf relative water content (RWC), chlorophyll concentrations (a, b and total) and shoot phosphorus concentration (SPC) while simultaneously increasing shoot proline levels and malondialdehyde (MDA) concentrations. AMF inoculation had positive effects on RWC, chlorophyll concentrations and SPC irrespective of sunflower cultivar and irrigation treatment. Shoot proline concentration and MDA reduced more in AM than non-AM plants. In most cases F. mosseae performed better than R. intraradices in terms of plant performance. Moreover, the improvements caused by AM fungi were more evident under water deficit than well-watered condition. It may be concluded that AM inoculation can alleviate the negative effects of water deficit stress on some important physio-biochemical traits of sunflower grown in the field, and can be considered as a practical and economical approach to improve crop performance in environments exposed to water limitations.

Engineering Approach for Production of Arbuscular Mycorrhizal Inoculum Adapted to Saline Soil Management

(1) Background: Soil salinity impacts plant growth and productivity in steppic regions. Thus, the current study aims at producing, at low cost, an inoculum composed of native arbuscular mycorrhizal fungi (AMF) strains adapted to saline soil management. (2) Methods: The propagation of the native AMF strains was carried out in three natural saline soils presenting increasing salinity levels (4.5, 8.5 and 9.3 dS·m−1 in Boughzoul (BG), Salt Rocket (SR) and Zaafrane (ZA) sites, respectively). Three host plant species (alfalfa, clover and leek) were tested as trap cultures. AMF spore richness and diversity, the quantification of soil microbial biomass and the determination of the most probable number (MPN) were carried out before and after 24 months culture. Moreover, the mycorrhizal rates of the host plant species were assessed. (3) Results: The moderate saline soil (SR) planted with alfalfa was found to be the most suitable for AMF inoculum production with a maximum of 650 spores, 10 g−1 of soil, a mycorrhizal rate of 86%, 70 propagules·g−1 of soil and the highest microbial biomass content. (4) Conclusion: This study points out the best combination for the production of a more adapted AMF biofertilizer for saline soil management and proposes several indicators for biofertilizer quality evaluation.

The Alien Invader, Rhus typhina L., Outperforms Its Native Competitor in the Scenario of Nitrogen Deposition and Arbuscular Mycorrhizal Fungi (AMF) Inoculation

Nitrogen deposition has been proven to facilitate the establishment of alien plants. Previous studies have certified that nitrogen deposition enhances the resource availability of habitats and promotes the growth of alien invaders. Arbuscular mycorrhizal fungi (AMF) symbiose with vascular plants and assist plants in nutrient acquisition. AMF colonization has been proven to be another driving factor of plant invasion. However, few studies have integrated nitrogen deposition and AMF inoculation into the exploration on invasion mechanism. Based on a trait approach, the present study subjected the alien invader, Rhus typhina L., and its co-occurring native species, Acer truncatum Bunge, to nitrogen deposition and AMF inoculation and compared the phenotypic variation in aboveground and belowground traits in an inter-specific competition experiment. Through the effects of different nitrogen deposition and AMF infection on the functional traits of R. typhina and A. truncatum, the effects of mycorrhizal symbiosis between R. typhina and A. truncatum on abiotic factors and interspecific relationships were analyzed. We found that inter-specific competition stimulated the colonization of AMF in R. typhina, however, decreased the colonization rate of AMF in A. truncatum. Correspondingly, inter-specific competition significantly reduced the plant growth of A. truncatum as the aboveground morphological traits including plant height and crown area, and belowground traits including root length, root surface area, root volume, number of root tips, number of root tip branches and number of root cross decreased for A. truncatum. Nitrogen deposition promoted the shoot growth of R. typhina rather than that of A. truncatum. AMF inoculation significantly affected the belowground traits of A. truncatum as the root length and root surface area significantly decreased after AMF inoculation in the mixture planting of the two species. The chlorophyll content of A. truncatum decreased without AMF inoculation, while nitrogen deposition enhanced the net photosynthetic rate of R. typhina. The alien invader R. typhina outperforms its native competitor in the simulated scenario of resource fluctuation and facilitates its establishment. We speculate that AMF colonization promotes the extension of R. typhina rhizosphere and, thus, accelerates the growth and invasion of R. typhina.