Search Results (94)

A low-scale Food Waste Compost (FWC1), characterized by optimal physic-chemical parameters and high organic matter percentages, was used as a fertilizer and a bio-stimulant for vegetable plants. Groups of treated plants were inoculated with active juveniles of root-knot nematodes to detect the effect on plant defense. Optimal amounts of compost mixed with soil increased plant biomass 30% compared to untreated plants. Moreover, when plants were inoculated, treated roots contained about 50% less sedentary forms (SFs) of nematodes and a lower reproduction rate of the parasites than untreated plants. Although the performance of FWC1 as defense activator was similar to other microbiome-generating commercial formulations, the compost was found to be the best fertilizer in both un- and inoculated plants. Diffuse root colonization by arbuscular mycorrhizal fungi (AMF) was observed after treatments with FWC1. FWC1 water extracts did not show any toxic effect on living nematode juveniles. Expression of the marker gene of immune response PR4b was found to be 3–5-fold higher in the roots of inoculated plants treated with FWC1 with respect to untreated plants, thus indicating that FWC1 primes plants against RKNs (root-knot nematodes, Meloidogyne incognita (Kofoid White) Chitw). Data are reported to associate immunization of plants with mycorrhization occurring in FWC1-treated plants. The proposed compost is indicated as having optimal performance both as a bio-fertilizer and a bio-stimulant. Full article

The arbuscular mycorrhizal fungi (AMF) effect on the plant metabolome is an actual question of plant biology. Its alteration during host plant development and at different phosphorus supplies is of special interest. The aim of this study was to evaluate the effect of Rhizophagus irregularis (Błaszk., Wubet, Renker & Buscot) C. Walker & A. Schüßler inoculation and/or phosphorus treatment on the root metabolome of Medicago lupulina L. subsp. vulgaris Koch at the first true leaf, second leaf, third leaf development stages, the lateral branching initiation, the flowering and the mature fruit stages. The assessment of metabolic profiles was performed using GC-MS. In total, 327 metabolites were annotated: among them 20 carboxylic acids, 26 amino acids, 14 fatty acids and 58 sugars. The efficient AM was characterized by the upregulation of the metabolism of proteins, carbohydrates and lipids, as well as an increase in the content of phosphates. The tricarboxylic acid abundance was generally lower during mycorrhization. Fourteen metabolic markers of the efficient AM symbiosis were identified. The lateral branching initiation stage was shown to have key importance. Long-lasting metabolomic profiling indicated variances in mycorrhization and Pi supply effects at different key stages of host plant development. Full article

Flavonoids serve as crucial plant antioxidants in drought tolerance, yet their antioxidant regulatory mechanisms within mycorrhizal plants remain unclear. In this study, using a two-factor design, trifoliate orange (Poncirus trifoliata (L.) Raf.) seedlings in the four-to-five-leaf stage were either inoculated with Funneliformis mosseae or not, and subjected to well-watered (70–75% of field maximum water-holding capacity) or drought stress (50–55% field maximum water-holding capacity) conditions for 10 weeks. Plant growth performance, photosynthetic physiology, leaf flavonoid content and their antioxidant capacity, reactive oxygen species levels, and activities and gene expression of key flavonoid biosynthesis enzymes were analyzed. Although drought stress significantly reduced root colonization and soil hyphal length, inoculation with F. mosseae consistently enhanced the biomass of leaves, stems, and roots, as well as root surface area and diameter, irrespective of soil moisture. Despite drought suppressing photosynthesis in mycorrhizal plants, F. mosseae substantially improved photosynthetic capacity (measured via gas exchange) and optimized photochemical efficiency (assessed by chlorophyll fluorescence) while reducing non-photochemical quenching (heat dissipation). Inoculation with F. mosseae elevated the total flavonoid content in leaves by 46.67% (well-watered) and 14.04% (drought), accompanied by significantly enhanced activities of key synthases such as phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), 4-coumarate:coA ligase (4CL), and cinnamate 4-hydroxylase (C4H), with increases ranging from 16.90 to 117.42% under drought. Quantitative real-time PCR revealed that both mycorrhization and drought upregulated the expression of PtPAL1, PtCHI, and Pt4CL genes, with soil moisture critically modulating mycorrhizal regulatory effects. In vitro assays showed that flavonoid extracts scavenged radicals at rates of 30.07–41.60% in hydroxyl radical (•OH), 71.89–78.06% in superoxide radical anion (O₂^•−), and 49.97–74.75% in 2,2-diphenyl-1-picrylhydrazyl (DPPH). Mycorrhizal symbiosis enhanced the antioxidant capacity of flavonoids, resulting in higher scavenging rates of •OH (19.07%), O₂^•− (5.00%), and DPPH (31.81%) under drought. Inoculated plants displayed reduced hydrogen peroxide (19.77%), O₂^•− (23.90%), and malondialdehyde (17.36%) levels. This study concludes that mycorrhizae promote the level of total flavonoids in trifoliate orange by accelerating the flavonoid biosynthesis pathway, hence reducing oxidative damage under drought. Full article

Arbuscular mycorrhizal fungi (AMF) play a key role in enhancing plant stress tolerance, nutrient uptake, and overall health, making them essential for sustainable agriculture. Their multifaceted contributions to the rhizosphere—through biofertilization, bioprotection, and biostimulation—have led to growing interest in their application. In recent years, in vitro mycorrhization has emerged as a promising approach for the rapid propagation of economically and ecologically important plant species, offering improved agronomic and physiological traits as well as increased resilience to environmental stressors. However, challenges remain in achieving consistent AMF-plant symbiosis under in vitro conditions across diverse species. This review highlights the potential of in vitro mycorrhization as a controlled system for investigating AMF interactions and their impact on plant development. Various in vitro mycorrhization systems are described and discussed, along with their applications in the mass production of AMF propagules and mycorrhizal plants, and their role in enhancing the acclimatization of micropropagated plantlets to ex vitro conditions. The role of in vitro mycorrhization as an effective tissue culture approach that integrates plant propagation with enhanced resilience to environmental stress is emphasized. The factors influencing the success of in vitro mycorrhization and strategies for the large-scale production of AMF propagules and mycorrhizal plants are explored. Although research in this area is still limited, existing studies underscore the potential of in vitro mycorrhization to enhance plant tolerance to abiotic and biotic stresses—an increasingly urgent goal in the context of climate change and global food security. Full article

Although many plant families are predominantly mycorrhizal, few symbiotic relationships between plants and arbuscular mycorrhizal fungi (AMF) have been thoroughly studied. Mycorrhized plants tend to exhibit greater tolerance to soil-borne pathogens and enhanced plant defence. Legumes, including common bean (Phaseolus vulgaris L.), are essential sources of protein globally. To improve common bean productivity, identifying efficient native microsymbionts is crucial. This study aimed to identify native AMF associated with common bean roots that could act as biostimulants and protect against soil diseases under varying environmental conditions. Agronomic trials were conducted at MBG-CSIC (Pontevedra, Spain) in 2021 and 2022, testing combinations of nitrogen fertilization, Burkholderia alba, Trichoderma harzianum, and a control. Traits such as nodulation, biomass, plant vigor, disease severity, nutrient content, and yield were evaluated. Four AMF species across three genera were identified. No consistent pattern was observed in AMF influence on agronomic traits. However, reduced mycorrhization in 2022 was associated with decreased nodulation, likely due to higher temperatures. Surprisingly, yields were higher in 2022 despite lower colonization. These findings suggest that intelligent use of AMF could reduce pesticide use, enhance sustainability, and promote healthier food systems. Continued research and conservation efforts are essential to optimize their benefits in legume production. Full article

The advancement of global warming and climate change requires strategic actions in understanding and seeking interactions between plant species and microorganisms that are more tolerant to water deficit. This research assessed the morpho-agronomic, physiological, and gene expression responses of two Passiflora cincinnata accessions (tolerant and sensitive) to water deficit, focusing on their relationship with mycorrhization. A randomized design with two accessions, two field capacities, and four AMF inoculation treatments was used to compare drought and control conditions. Differential gene expression was analyzed under drought stress, and the effect of mycorrhization on stress tolerance was evaluated. The results showed that inoculation with native arbuscular mycorrhizal fungi (AMF) communities, especially those from water-deficit conditions (AMF25), resulted in greater increases in height, number of leaves, stem diameter, number of tendrils, leaf area, and fresh biomass of root and shoot, with increases ranging from 50% to 300% compared to the control (non-inoculated) and monospecific inoculation (Entrophospora etunicata). Higher photosynthetic rate and water use efficiency were observed in the tolerant accession. Mycorrhizal inoculation increased the total chlorophyll content in both accessions, especially when inoculated with native AMF communities. Overall, P. cincinnata showed higher mycorrhizal responsiveness when inoculated with native AMF communities compared to monospecific inoculation with E. etunicata. The tolerant accession showed overexpression of the genes PcbZIP, PcSIP, and PcSTK, which are associated with signal transduction, water deficit tolerance, osmoregulation, and water transport. In contrast, the water deficit-sensitive accession showed repression of the PcSIP and PcSTK genes, indicating their potential use for distinguishing tolerant and sensitive accessions of the species. The tolerance of P. cincinnata to water deficit is directly related to physiological responses, increased photosynthetic rate, efficient water use, and regulation of gene expression. Full article

Soil salinization is a growing global concern in many ecosystems. Although ectomycorrhizal fungi have been shown to alleviate the effects of salinity in some tree species, uncertainties persist concerning their effectiveness when plants are exposed to different salinity levels that are commonly present in salt-affected soils. Quercus dentata seedlings either non-inoculated (mycorrhizal control) or inoculated with the ectomycorrhizal fungus Laccaria bicolor were then treated with three NaCl concentrations (0, 0.4%, and 0.8%). The physiological, stoichiometric, and growth characteristics of the plants were examined. NaCl significantly affected seedling growth and physiology. However, the impact of L. bicolor on Q. dentata seedlings could shift in response to varying salt concentrations. Under moderate salinity, inoculation of L. bicolor increased root biomass by 4.55% and leaf chlorophyll concentrations by 46.8%, and decreased leaf Na⁺ concentrations and the Na⁺/K⁺ ratios. Under high salinity, L. bicolor decreased leaf water content and fluorescence parameters, and increased leaf Na⁺ concentrations. The effect of ectomycorrhizal fungus L. bicolor on Q. dentata seedlings was dependent on NaCl concentration, and our results indicate that the use of L. bicolor in afforestation efforts with Q. dentata would only be effective under relatively low soil salinity levels. Full article

The low availability of phosphorus (P) in soil is one of the main constraints on crop production. Plants have developed several strategies to increase P use efficiency, including modifications in root morphology, the exudation of different compounds, and associations with microorganisms such as arbuscular mycorrhizal fungi (AMF). This study aimed to investigate the effect of sorgoleone compound on AMF colonization and its subsequent impact on P uptake, rhizosphere microbiota, and sorghum growth. The experiment was conducted in a greenhouse using the sorghum genotype P9401, known for low sorgoleone production. Three doses of purified sorgoleone (20 μM, 40 μM, and 80 μM) were added to low-P soil and plants were harvested after 45 days. Treatments included inoculation with the arbuscular mycorrhizal fungi Rhizophagus clarus and a negative control without inoculum. The addition of 40 and 80 μM of sorgoleone did not significantly increase mycorrhization. However, treatment with 20 μM sorgoleone combined with R. clarus inoculation significantly increased total sorghum biomass by 1.6-fold (p ≤ 0.05) compared to the non-inoculated treatment. AMF inoculation influenced only AMF colonization and the fungal microbiota, without affecting the bacterial community, whereas sorgoleone showed no effect on either. The activities of acid and alkaline phosphatases in the rhizospheric soil did not differ significantly among the treatments. Furthermore, the sorghum genes CYP71AM1, associated with sorgoleone biosynthesis, and Sb02g009880, Sb06g002560, Sb06g002540, and Sb03g029970 (related to phosphate transport induced by mycorrhiza) were significantly upregulated (p ≤ 0.05) in fine roots under these conditions. The 20 μM concentration of sorgoleone can enhance AMF colonization in sorghum and promote plant growth under low-P conditions, without significantly altering the microbiota. Full article

Lettuce cultivation requires high fertilizer inputs, which impact the environment and costs. Arbuscular mycorrhizal symbiosis (AMS) can reduce fertilizer use, enhance plant nutrition (especially phosphorus), and promote healthier plants. Class III peroxidases (PRXs) play crucial roles in various physiological processes and stress responses. However, their role in AMS and phosphorous (P) deficiency is still unclear. Our study identified 91 PRX genes in the lettuce genome (LsPRXs) and clustered them into eight subfamilies based on phylogenetic relationships. Evolutionary analysis indicated that tandem duplication was the main driver for LsPRX gene family expansion. Synteny analysis showed orthologous relationships of the PRX gene family between lettuce and potato, Arabidopsis, and maize, identifying 39, 28, and 3 shared PRXs, respectively. Transcriptomic data revealed that most LsPRX genes were more expressed in roots than in leaves and differentially expressed LsPRXs were found in response to AMS and P supply. Notably, 15% of LsPRX genes were differentially expressed in roots during mycorrhization. Gene expression network analysis highly correlated five LsPRXs (LsPRX17, LsPRX23, LsPRX24, LsPRX64, and LsPRX79) with genes involved in cell wall remodeling and reorganization during mycorrhization. Our results provide insights into the evolutionary history and functional roles of PRX genes in lettuce and identify candidate gene targets that may enhance the bio-stimulant effects of AMS and help to cope with P deficiency. Full article

Tuber aestivum is a key truffle species with significant ecological and economic value. Despite its importance, plantation success can be influenced by soil pH, host plants, and undesired fungi. This study examines how soil pH and host plants influence mycorrhization trends in T. aestivum plantations across six plant species in eight Hungarian settlements, using root sampling and DNA analysis to assess plantations at three and six years of age. Tuber aestivum achieved over 30% mycorrhization, with Carpinus betulus showing the highest levels. DNA analysis identified eight undesired mycorrhizal fungi, with Suillus spp. (42.9%) and Scleroderma spp. (31.4%) being the most prevalent. The study found that T. aestivum preferred a soil pH of around 7.6, while undesired fungi thrived in slightly acidic conditions. Additionally, soil pH significantly and positively influenced T. aestivum mycorrhization; however, factors such as plantation age also contributed to mycorrhization trends. While mycorrhization by undesired fungi decreased with higher soil pH, it increased as plantations matured from three to six years. These findings highlight the need for the effective management of soil pH and the control of undesired fungi to optimize T. aestivum mycorrhization, emphasizing the importance of targeted strategies and further research for sustainable truffle cultivation. Full article

The soil microbiota is a key component of agroecosystems, and understanding its traits is crucial for effective agronomic management. Among beneficial microorganisms, arbuscular mycorrhizal fungi (AMFs) are mutually associated with grapevine (Vitis vinifera L.), enhancing the ability of this cropping system to adapt to soil conditions and bolstering its resistance and resilience against abiotic stresses, particularly drought, by promoting root growth and enhancing the roots’ absorption surface. The objective of this on-field study was to determine AMF species richness and diversity along with their relation to soil chemical, physical, and biological characteristics in two adjacent organic vineyards in Central Italy. The two tested vineyards of the autochthonous cv. Aleatico differed by the presence of grafted (Vitis berlandieri × V. riparia rootstock; AL-420) or own-rooted (ungrafted V. vinifera L.; AL-ORV) vines. To this aim, soil and root samples were collected and geo-referenced. Analysis of the AMF species colonizing roots of both AL-ORV and AL-420 revealed the presence of four species: Scutellospora alterata, Paraglomus laccatum, Acaulospora laevis, and A. baetica, with S. alterata being the most frequent. Mycorrhization parameters were higher in the roots of grafted plants compared to ungrafted ones. A high beta-glucosidase (BG):N-acetylglusosaminidase (NAG) ratio in two tested vineyards indicated that microbes utilized more cellulose than chitin and peptidoglycan as dominant C resources. A negative correlation between mycorrhization rate (MyCP) and BG was observed, likely because AMFs form mutualistic relationships with plants, depending on the host plant for carbon. Results revealed a positive correlation between the degree of mycorrhizal association and the species involved, with the presence of copper and nickel among metals. Negative correlations were found concerning soil clay content along with beta-glucosidase. In conclusion, the grapevine root system was characterized by a differential symbiotic relationship with AMF species, whose development is influenced by the root genotype, soil texture, and biochemistry. Specifically, the increased frequency of AMFs in relation to copper content strengthens the evidence of their role in maintaining a vine’s production capacity in the event of soil contamination by this element. Full article

Arbuscular mycorrhizal fungi (AMF) are soil microorganisms living in symbiosis with most terrestrial plants. They are known to improve plant tolerance to numerous abiotic and biotic stresses through the systemic induction of resistance mechanisms. With the aim of developing more sustainable agriculture, reducing the use of chemical inputs is becoming a major concern. After providing an overview on AMF history, phylogeny, development cycle and symbiosis benefits, the current review aims to explore the potential of AMF as biostimulants and/or biocontrol agents. Nowadays, AMF inoculums are already increasingly used as biostimulants, improving mineral nutrient plant acquisition. However, their role as a promising tool in the biocontrol market, as an alternative to chemical phytosanitary products, is underexplored and underdiscussed. Thus, in the current review, we will address the mechanisms of mycorrhized plant resistance to biotic stresses induced by AMF, and highlight the various factors in favor of inoculum application, but also the challenges that remain to be overcome. Full article

In the face of persistent soil degradation in Benin caused by poor agricultural practices, including excessive use of chemical fertilizers, it is urgent to find solutions that take into account the microorganisms of interest. This study aimed to assess the effect of combining three strains of indigenous arbuscular mycorrhizal fungi (AMF) on maize production in northern Benin. The study involved 34 growers in Ouénou, Bagou and Kokey. The experimental setup consisted of three elementary plots with three treatments. Growth parameters were measured every 15 days, from the 15^th to the 60^th day after sowing, on ten plants per plot. Plant nutritional status, grain yield and mycorrhization were measured. The results showed that biostimulant + 50% NPK_Urea (N = nitrogen, P = phosphorus and K = potassium) had similar positive effects on growth parameters to those induced by the application of 100% NPK_Urea. Gains of 30.25% to 36.35% were recorded in plant height at Kokey. On the other hand, biostimulant+ 50% NPK_Urea induced a better phosphorus uptake of 21.08% to 27.77%. In addition, the grain yield of mycorrhizal plants was 8.37% higher than that of plants receiving 100% NPK_Urea at Ouénou. These results show that this technology could be integrated into the agricultural system to promote sustainable maize growing in Benin. Full article

The effect of plant cultivar on the degree of mycorrhization and the benefits mediated by arbuscular mycorrhizal fungi (AMF) have been documented in many crops. In apple, a wide variety of rootstocks are commercially available; however, it is not clear whether some rootstock genotypes are more susceptible to mycorrhization than others and/or whether AMF species identity influences rootstock compatibility. This study addresses these questions by directly testing the ability/efficacy of four different AMF species (Rhizophagus irregularis, Septoglomus deserticola, Claroideoglomus claroideum or Claroideoglomus etunicatum) to colonize a variety of commercially available Geneva apple rootstock genotypes (G.11, G.41, G.210, G.969, and G.890). Briefly, micropropagated plantlets were inoculated with individual species of AMF or were not inoculated. The effects of the rootstock genotype/AMF interaction on mycorrhization, plant growth, and/or leaf nutrient concentrations were assessed. We found that both rootstock genotype and the identity of the AMF are significant sources of variation affecting the percentage of colonization. However, these factors largely operate independently in terms of the extent of root colonization. Among the AMF tested, C. etunicatum and R. irregularis represented the most compatible fungal partners, regardless of apple rootstock genotype. Among the rootstocks tested, semi-dwarfing rootstocks appeared to have an advantage over dwarfing rootstocks in regard to establishing and maintaining associations with AMF. Nutrient uptake and plant growth outcomes were also influenced in a rootstock genotype/AMF species-specific manner. Our findings suggest that matching host genetics with compatible AMF species has the potential to enhance agricultural practices in nursery and orchard systems. Full article

Climate change (CC) threatens Mediterranean viticulture. Rhizospheric microorganisms may be crucial for the adaptation of plants to CC. Our objective was to assess whether the association of two grapevine varieties with arbuscular mycorrhizal fungi (AMF) increases grapevine’s resilience to environmental conditions that combine elevated atmospheric CO₂, increased air temperatures, and water deficit. Tempranillo (T) and Cabernet Sauvignon (CS) plants, grafted onto R110 rootstocks, either inoculated (+M) or not (−M) with AMF, were grown in temperature-gradient greenhouses under two environmental conditions: (i) current conditions (ca. 400 ppm air CO₂ concentration plus ambient air temperature, CATA) and (ii) climate change conditions predicted by the year 2100 (700 ppm of CO₂ plus ambient air temperature +4 °C, CETE). From veraison to maturity, for plants of each variety, inoculation treatment and environmental conditions were also subjected to two levels of water availability: full irrigation (WW) or drought cycles (D). Therefore, the number of treatments applied to each grapevine variety was eight, resulting from the combination of two inoculation treatments (+M and −M), two environmental conditions (CATA and CETE), and two water availabilities (WW and D). In both grapevine varieties, early drought decreased leaf conductance and transpiration under both CATA and CETE conditions and more markedly in +M plants. Photosynthesis did not decrease very much, so the instantaneous water use efficiency (WUE) increased, especially in drought +M plants under CETE conditions. The increase in WUE coincided with a lower intercellular-to-atmospheric CO₂ concentration ratio and reduced plant hydraulic conductance. In the long term, mycorrhization induced changes in the stomatal anatomy under water deficit and CETE conditions: density increased in T and decreased in CS, with smaller stomata in the latter. Although some responses were genotype-dependent, the interaction of the rootstock with AMF appeared to be a key factor in the acclimation of the grapevine to water deficit under both current and future CO₂ and temperature conditions. Full article