Search Results (191)

Four biostimulants (phycocyanin, γ-aminobutyric acid (GABA), glycine betaine (GB), and the mycorrhizal fungus Rhizophagus intraradices) were applied foliarly to six cultivars of mature creeping bentgrass (Agrostis stolonifera) under non-stressed greenhouse conditions. Phycocyanin was most effective at increasing total shoot greenness, which was most consistent over time with the cultivars Penncross, T1, and Tyee. GABA was most effective at increasing total root fresh and dry weight, most strongly for Penncross and T1, respectively. GB was most effective at increasing total shoot fresh and dry weight, with both most strongly increased for Tyee. By comparison, R. intraradices had relatively low effectiveness for increasing any of these parameters. The appearance of the grass at the end of the experiment revealed that 007 and Focus generally showed the most and least growth benefit, respectively, with all four biostimulants. However, all cultivars showed increases in more than one parameter for each biostimulant, and thus, no cultivar was uniformly responsive or non-responsive to all the biostimulants. This research shows that phycocyanin, GABA, and GB may benefit multiple creeping bentgrass cultivars under non-stressed conditions, but each one tended to be more beneficial to a particular aspect of plant growth and quality. End users need to be aware of the importance of creeping bentgrass genotype when considering biostimulant application. Full article

Drought stress significantly hinders the cultivation of medicinal plants such as licorice (Glycyrrhiza uralensis), valued for its bioactive compounds, glycyrrhizin, and liquiritin. This study aims to investigate how co-inoculation with arbuscular mycorrhizal fungus Rhizophagus irregularis and Trichoderma harzianum can enhance licorice drought tolerance and secondary metabolite production, providing insights for sustainable agriculture in arid regions. The results demonstrate that inoculation with R. irregularis significantly improved biomass, drought stress tolerance, and increased glycyrrhizin and liquiritin concentrations by 29.9% and 3.3-fold, respectively, particularly under drought conditions. Co-inoculation with T. harzianum further boosted glycyrrhizin yield by 93.7%, indicating a synergistic relationship between the two microbes. The expression of key biosynthetic genes, including squalene synthase (SQS1) for glycyrrhizin and chalcone synthase (CHS) for liquiritin, was significantly upregulated, enhancing water use efficiency and the biosynthesis of secondary metabolites. Nutrient analysis showed improved phosphorus uptake, alongside reduced root carbon and nitrogen concentrations, leading to greater nutrient utilization efficiency. These findings suggest that co-inoculating R. irregularis and T. harzianum is a promising approach to improving licorice growth and medicinal quality under drought stress, with broad applications for sustainable crop management. Full article

Understanding species-specific mechanisms governing symbiotic fungal responses to plant traits and soil factors is critical for optimizing urban tree “plant-soil-fungus” systems under pollution stress. To address this gap, we combined δ¹³C/δ¹⁵N isotope analysis and ITS sequencing for three common street trees in Beijing: Sophora japonica, Ginkgo biloba, and Populus tomentosa. In S. japonica, symbiotic fungal abundance was positively associated with leaf δ¹⁵N, indicating root exudate-mediated “plant-microbe” interactions during atmospheric NO_x assimilation. G. biloba, with weak NO_x assimilation, exhibited a negative correlation between fungal abundance and soil available N/P, suggesting mycorrhizal nutrient compensation under low fertility. P. tomentosa showed decreased fungal abundance with increasing soil N/P ratios and specific leaf area, reflecting carbon allocation trade-offs that limit mycorrhizal investment. These results demonstrate that symbiotic fungi respond to atmospheric and edaphic drivers in a tree species-dependent manner. Urban greening strategies should prioritize S. japonica for its NO_x mitigation potential and optimize fertilization for G. biloba (nutrient-sensitive fungi) and P. tomentosa (nutrient balance sensitivity). Strategic mixed planting of P. tomentosa with S. japonica could synergistically enhance ecosystem services through complementary resource acquisition patterns. This study provides mechanism-based strategies for optimizing urban tree management under atmospheric pollution stress. Full article

With the continuous change of climate, drought stress has emerged as the primary constraint on crop growth, posing a significant threat to the stability of global grain reserves. Arbuscular mycorrhizal fungi (AMF), as a kind of widely distributed root endophytes, enhance the drought tolerance of maize (Zea mays L.) through regulating the physiological and molecular responses. However, comprehensive transcriptome analysis to reveal the molecular mechanism of drought tolerance in the symbiotic process between AMF and maize is still limited. In the potted plant experiment, maizes inoculated with and without arbuscular mycorrhizal fungus Funneliformis mosseae were grown under well-watered (WW) or drought-stressed (DS) conditions. By using RNA-Seq and transcriptome analysis on maize roots and leaves, this work aimed to investigate the differential expressed genes (DEGs) related to the Ca²⁺ signaling pathway induced by AMF symbiosis under drought stress. Our findings indicated that F. mosseae inoculation resulted in a decrease in the net fluxes of Ca²⁺, while simultaneously elevating Ca²⁺ contents in the maize roots and leaves under well-watered or drought-stressed conditions. Notably, 189 DEGs were regulated not only by AMF symbiosis and drought stress, but also exhibited preferential expression in either leaves or roots. The annotation and enrichment of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) showed that most of the DEGs were significantly enriched in Ca²⁺ signaling pathway genes, related to signal transduction, cellular process, and defense response. A high number of DEGs with this function (including calcineurin B-like protein (CBL), CBL-interacting protein kinase (CIPK), mitogen-activated protein kinase (MAPK), and calcium-dependent protein kinase (CDPK) receptor kinases) were upregulated-DEGs or downregulated-DEGs in F. mosseae-inoculated maizes under drought stress. Furthermore, some DEGs belong to transcription factor (TF) families, including bHLH ERF, and, MYB, were speculated to play key roles in improving the drought tolerance of maize. Based on the expression data and co-expression analysis between TF and Ca²⁺ signaling pathway genes, Whirly1 with CBL11, and BRI1-EMS-SUPPRESSOR 1 (BES1) with CBL10, CIPK24, CDPK1, CDPK14, CDPK19, and MAPK9 genes showed significant positive correlations, while B3 domain-containing transcription factors (B3 TFs) with MAPK1 and both CBL9 genes showed significant negative correlations in response to both F. mosseae inoculation and drought stress. The regulation of Ca²⁺ signaling pathways by AMF symbiosis was an important response mechanism of maize to improve their drought resistance. This study provides insightful perspectives on how AMF-induced modulation of gene expression within the Ca²⁺ signaling pathway can enhance the drought tolerance of mycorrhizal maize in the future. Full article

The roles of endophytes in Cannabis sativa (cannabis, hemp) remain poorly explored. While in vitro studies suggest that there can be several benefits, such as plant growth promotion and protection against pathogens, more in planta studies are needed. This review summarizes the bacterial and fungal endophytes previously reported in tissues of C. sativa and discusses the factors influencing their presence, as well as their potential beneficial and detrimental effects. Using genome sequencing and culture-based approaches, we describe the microbial diversity in hydroponically cultivated cannabis plants at several developmental stages. These include mother plants, cuttings, vegetative and flowering plants, and tissue-cultured plantlets. Microbes that were present include fungal, yeast, and bacterial endophytes found in roots, stems, leaves, inflorescences, and seeds. These may have originated from the growing substrate or be transmitted through vegetative propagation. Notable endophytes included Rhizophagus irregularis (a mycorrhizal fungus), Penicillium chrysogenum (an antibiotic producer), and various endophytic yeast species not previously described in C. sativa. Endophytes representing potential plant pathogens, such as Fusarium oxysporum, are also present within cannabis tissues, which can negatively impact plant health. Using scanning electron microscopy, we observed that fungal propagules are present within pith parenchyma cells and xylem vessel elements in stem tissues, illustrating for the first time the in situ localization and distribution of endophytes in cannabis vascular tissues. The mechanism of spread through xylem vessels likely contributes to the spread of endophytes within cannabis and hemp plants. Further research is required to validate the roles of endophytes in cannabis and hemp plants grown under commercial production conditions. Full article

Salinity represents a major environmental factor limiting plant growth and productivity. In order to better understand the effects of arbuscular mycorrhizal fungus Claroideoglomus etunicatum and Indole-3-acetic acid (IAA) on the growth and chemical composition of vetiver grass (Vetiveria zizanioides) under salt stress, a factorial experiment was conducted in a completely randomized design with three replications. The experiment included four NaCl levels (0, 8, 16, and 24 decisiemens per meter (dS/m)) and four levels of treatments (no amendment application, application of IAA, application of C. etunicatum, and interaction of IAA and C. etunicatum) with three replications. The results of the experiment showed that the addition of sodium chloride increased the concentration of proline and the activities of catalase, peroxidase, and superoxide dismutase enzymes. The application of the growth regulator (IAA) and C. etunicatum significantly increased the fresh and dry weight (101%) of shoots, dry weight of roots, and the concentration of macro- and micro-elements in shoots under salinity condition (99.82% phosphorus; 9.79% Iron). The application of mycorrhiza and auxin significantly reduced the concentration of proline and the activities of catalase, peroxidase, and superoxide dismutase enzymes. In general, the addition of IAA and C. etunicatum to roots under salt stress conditions can improve growth and increase the concentration of some nutrients in vetiver shoots. Full article

In vitro cultivation of arbuscular mycorrhizal fungi (AMF) is challenging due to their biotrophic symbiosis. The principal aim of this study was to demonstrate the effect of establishing in vitro dual cultures of arbuscular mycorrhizal fungi (AMF) inoculated on Swietenia macrophylla (mahogany) roots on plant growth. Furthermore, it was sought to demonstrate that plant colonization by Glomeromycota can be achieved with a replicable protocol. This study established monoxenic cultures of carrot (Daucus carota) Ri T-DNA ROC inoculated with Glomus sp. on two-compartment plates. At 75 days, hyphal growth reached 223.93 mm in the root compartment and 103.71 mm in the hyphal compartment. Spores produced in vitro measured 26.14 ± 1.70 µm, smaller than ex vitro spores (101.2 ± 4.22 µm). Rhodotorula mucilaginosa was isolated from cultures and appeared to stimulate hyphal growth and root–fungal contact. From these cultures, a dual culture of mahogany inoculated with Glomus sp. was established. No significant differences were observed between inoculated and non-inoculated plants in stem length, root length, root number, or leaf number at 30 days. Spore production ranged from 10,166 to 27,696 per plate, averaging 14,795 ± 3301, with hyphal lengths of 3655.46 ± 308.75 mm. Hyphal development included running and branching patterns, with solitary and clustered spores. Spore diameter averaged 27.68 ± 3.85 µm. Arbuscular colonization reached 41.49% at 30 days and 52.13% at 75 days, exceeding rates reported for other culture systems. Monoxenic cultures are a reliable, aseptic source of high-quality inoculum, supporting biofertilizer production and biotechnological applications. These methods provide valuable tools for studies involving AMF, such as those demonstrated with mahogany. Full article

Arbuscular mycorrhizal fungi (AMFs) can alleviate salt stress in plants by promoting growth. The mitigating effect of the AMF Gigaspora albida on the physiology, growth, and Na⁺/K⁺ balance in heirloom maize under different dilutions of saline wastewater was evaluated. The study was conducted in a greenhouse under a completely randomized design (CRD) in a 3 × 4 factorial scheme, with six replicates. The treatments consisted of three mycorrhizal conditions (M1—control plants without the AMF; M2—plants inoculated with G. albida; and M3—plants inoculated with G. albida plus the soil microbiota) and four levels of electrical conductivity (ECw): 0.5, 1.8, 3.1, and 4.4 dS m⁻¹. The results indicate that saline wastewater affects the physiology of heirloom maize. The symbiosis in M2 and M3 mitigated the stress in PSII by dissipating heat. The M3 treatment alleviated ionic stress in maize, reduced the Na⁺/K⁺ ratio in the aerial part, and increased the MSPA, MSRA, AP, and DC at EC_a levels of 1.8 and 3.1 dS m⁻¹. The M1 plants adapted by investing in root growth to tolerate the high salinity. In M2, the plant–AMF interaction did not mitigate the effects of high salinity, showing the worst growth performance. The saline wastewater reduced the percentage of G. albida colonization. An EC_a of 2.9 dS m⁻¹ favored a high spore density. Full article

Orchids produce tiny, light seeds (dust-like seeds without endosperm) that rely on specific symbiotic fungi for successful germination. Plant roots often release small signaling molecules or bioactive compounds to attract arbuscular mycorrhizal (AM) fungi, promoting fungal growth and hyphal branching. However, until now, no such bioactive or signaling molecules have been identified in orchids that help recruit fungi for seed germination. In this study, we used metabolomics and UPLC-Q-TOF-MS/MS, combined with a molecular network approach, to explore potential bioactive/signaling molecules in the seeds of the achlorophyllous orchid Gastrodia elata Bl. Our analysis revealed the presence of amino acids, nucleotides, lipids, organic acids, saccharides, phospholipids, and lignanamides. Specifically, organic acids, saccharides, and lignanamides were shown to promote the growth of Mycena osmundicola, a fungus important for seed germination. Additionally, lignanamides inhibited the plant pathogen Fusarium oxysporum and exhibited strong antioxidant and anti-inflammatory activities. This is the first systematic identification of bioactive/signaling molecules in G. elata Bl. seeds, providing new insights into the symbiotic relationship between orchids and fungi. 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

Tuber is a rare edible and medicinal fungus with a global distribution. The Macrosporum lineage within Tuber is a relatively small and infrequent clade, which has been receiving increasing attention due to the presence of an endangered species, T. gigantosporum. However, the species diversity, phylogenetic relationships, geographic distribution, and ecological characteristics of the Macrosporum group remain poorly understood. Through extensive sampling and combining the accurate and available global specimen and mycorrhizal data, 19 Tuber specimens from Southwest China were studied based on morphology, molecular systematics, and ecology. The specimens were identified as T. calosporum, T. glabrum, and T. sinomacrosporum within the Macrosporum group, with detailed descriptions provided, particularly supplementing the taxonomic features of T. glabrum. A classification key for the Macrosporum group species is also provided. The geographic distribution of specimens and diverse hosts suggest that the Macrosporum clade displays wider ecological adaptability. This study is important to better understand the diversity and conservation measures of Tuber resources throughout the world. Full article

Globally, escalating soil salinization poses significant abiotic stress, disproportionately impacting crops like chickpea (Cicer arientinum L.). This legume exhibits high sensitivity to salinity, which disrupts various physiological and metabolic processes, ultimately hindering growth and productivity. AMF (arbuscular mycorrhizal fungus) reduces salt’s detrimental effects on plants’ growth by bolstering the plant’s antioxidant defense system, effectively reducing the damage caused by oxidative stress. In this study, the impact of AMF on salinity stress alleviation in chickpea was investigated in pot-grown experiments. Rhizophagus fasciculatus was used to inoculate the seeds of three different chickpea varieties (HC-3, CSG-8962, and C-235), and the physiological and biochemical changes of the AMF-inoculated and non-inoculated chickpea plants were studied. When exposed to salinity stress, the plants exhibited decreased leaf relative water content (RWC %) (21.13–31.30%), increased leaf relative stress injury, decreased chlorophyll content (45.22–58.24%), photochemical quantum yield, photosynthetic rate, transpiration rate, and stomatal conductance as compared to the control plants, but opposite results were observed in AMF colonized plants. A 9.16% to 14.79% increase in chlorophyll content was reported after AMF colonization. The activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX) were increased by salt stress. They were further enhanced by AMF inoculation SOD activity by 20.3% to 23.3%, CAT activity by 65.7% to 78.7%, and POX activity by 32.7% to 39.3%. The findings clearly show that AMF Rhizophagus fasciculatus, via enhancing RWC, photosynthetic parameters, and antioxidant enzymes, can mitigate salinity stress in chickpeas. Full article

Zeolite, a microporous mineral with strong ion binding, can enhance nutrient availability and growth of plants, such as maize (Zea mays L.). Arbuscular mycorrhizal (AM) symbiosis has also been shown to enhance nutrient availability and growth of plants, including maize. However, the interaction between AM symbiosis and zeolite is poorly understood. In this study, the effect on growth of maize was examined following soil treatment with N-enriched (ZN+) zeolite, which could retain 19.68% N, or N-free zeolite (ZN−), compared to N-enriched or N-free vermiculite (VN+ and VN−). There was a 2.7-times increase in the growth of maize under ZN+ treatment compared to ZN−, indicating that N could be released from zeolite for plant growth, and a 3.8-times increase with ZN+ treatment compared to VN− or VN+, indicating that zeolite was more effective than vermiculite in releasing N for plant growth. Subsequently, ZN+ and ZN− treatments were examined with non-AM (M−) and AM (M+) treatments using Rhizophagus irregularis. ZN+ M+ treatment led to higher AM colonization and development compared to M+ ZN−treatment, indicating an interaction of AM in roots with N from zeolite. PCA revealed improvements in leaf N content, photosynthetic pigments, photosynthetic performance, and secondary metabolites with M+ ZN+ treatment, which was also observed in comparison to M−ZN+ and M− ZN−treatments, further supporting the benefit of combining N from zeolite with an AM fungus. The combination of N released from N-enriched zeolite and AM symbiosis offers a promising alternative to chemical fertilizers to improve maize growth. Full article

The use of living organisms to treat human by-products, such as residual sludge, has gained interest in the last years. Fungi have been used for bioremediation and improving plant performance in contaminated soils. We investigated the impact of the mycorrhizal fungus (MF) Gigaspora roseae and the saprophytic fungus (SF) Coriolopsis rigida on the survival and growth of Quillaja saponaria seedlings cultivated in a sandy substrate supplemented with residual sludge. Q. saponaria is a sclerophyllous tree endemic to Chile, known for its high content of saponins. We inoculated plants with the MF, the SF, and a combination of both (MF + SF). Following inoculation, varying doses of liquid residual sludge equivalent to 0, 75, and 100% of the substrate’s field capacity were applied. After 11 months, we found a positive influence of the utilized microorganisms on the growth of Q. saponaria. Particularly, inoculation with the SF resulted in higher plant growth, mycorrhizal colonization percentage, and higher enzymatic activity, especially after the application of the sludge. This increase was more evident with higher doses of the applied sludge. These results highlight the potential of combined microorganism and residual sludge application as a sustainable strategy for enhancing plant growth and reducing waste. Full article

Researchers are exploring plant-based protein sources to address both malnutrition and climate change. Desert truffles are rich in protein (i.e., $\approx$20%) and offer a cheaper and more environmentally friendly option. However, desert truffle cultivation is limited by environmental factors like rainfall and soil properties. This study was conducted to understand the soil conditions and microbiomes associated with desert truffles growing in parts of Saudi Arabia. Based on yield, the truffle fields were categorized into high-yield ($\approx$50 kg/ha annually) and low-yield ($\approx$2 kg/ha annually) truffle farms. Truffle yield differences were not significantly influenced by most soil physicochemical variables except for total nitrogen (negatively correlated). However, low soil nitrogen alone did not explain yield disparities, as wild truffle fields with low nitrogen also produced fewer truffles. In contrast, truffle yield showed a strong positive correlation with calcium carbonate content. We hypothesized that the unmeasured irrigation schedule was most likely behind the truffle yield differences especially during fruiting season. Furthermore, the high-yield farms had lower bacteria richness and diversity than the low-yield farms. Environmentally important bacteria genera such as Geodermatophilus and Rubrobacter were found in both farms, although more were found in the low-yield one, whereas more Streptomyces were found in the high-yield farm. In addition, fungal alpha diversity was higher in the high-yield farm with the dominance of Sordariomycetes, Dothideomycetes, Eurotiomycetes, and Glomeromycetes. Full article