Search Results (202)

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 is an important abiotic stress factor restricting crop production. Broomcorn millet (Panicum miliaceum L.) has become an ideal material for analyzing the stress adaptation mechanisms of crops due to its strong stress resistance. However, the functional characteristics of its rhizosphere microorganisms in response to drought remain unclear. In this study, metagenomics and metabolomics techniques were employed to systematically analyze the compositional characteristics of the microbial community, functional properties, and changes in metabolites in the rhizosphere soil of broomcorn millet under drought stress. On this basis, an analysis was conducted in combination with the differences in functional pathways. The results showed that the drought treatment during the flowering stage significantly altered the species composition of the rhizosphere microorganisms of broomcorn millet. Among them, the relative abundances of beneficial microorganisms such as Nitrosospira, Coniochaeta, Diversispora, Gigaspora, Glomus, and Rhizophagus increased significantly. Drought stress significantly affects the metabolic pathways of rhizosphere microorganisms. The relative abundances of genes associated with prokaryotes, glycolysis/gluconeogenesis, and other metabolic process (e.g., ribosome biosynthesis, amino sugar and nucleotide sugar metabolism, and fructose and mannose metabolism) increased significantly. Additionally, the expression levels of functional genes involved in the phosphorus cycle were markedly upregulated. Drought stress also significantly alters the content of specific rhizosphere soil metabolites (e.g., trehalose, proline). Under drought conditions, broomcorn millet may stabilize the rhizosphere microbial community by inducing its restructuring and recruiting beneficial fungal groups. These community-level changes can enhance element cycling efficiency, optimize symbiotic interactions between broomcorn millet and rhizosphere microorganisms, and ultimately improve the crop’s drought adaptability. Furthermore, the soil metabolome (e.g., trehalose and proline) functions as a pivotal interfacial mediator, orchestrating the interaction network between broomcorn millet and rhizosphere microorganisms, thereby enhancing plant stress tolerance. This study sheds new light on the functional traits of rhizosphere microbiota under drought stress and their mechanistic interactions with host plants. 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

Excessive application of a chemical fertilizer during rice cultivation leads to soil infertility and increases production costs. An alternative way to reduce over-fertilization is to partially or fully replace the fertilizer with microbes that promote the growth and production of plants. This study aimed to investigate the Maled Phai rice cultivar (Oryza sativa L.) in a field experiment with two fungi strains. Rhizophagus variabilis KS-02 and Trichoderma zelobreve PBMP16 were selected as inocula and compared with non-R. variabilis KS-02 and non-T. zelobreve PBMP16, acting as controls, one without synthetic fertilizer and one with synthetic NPK fertilizer. The field experiment was conducted in a Randomized Complete Block design with four replications. Growth and yield parameters were determined in the plant tissues and roots, and bioactive compounds were determined in the rice seeds. The results show the presence of T. zelobreve PBMP16 and R. variabilis KS-02 colonization in the plant roots at the harvest stage. A single inoculum of both R. variabilis KS-02 and T. zelobreve PBMP16 significantly increased most of the plant growth performance and yield parameters, as well as the concentrations of bioactive compounds. Remarkably, such effects were more apparent than those observed with the use of a chemical fertilizer. Thus, a single inoculum of R. variabilis KS-02 or T. zelobreve PBMP16 and the co-inoculation of both have the potential to increase the grain yield and bioactive compounds of Maled Phai under field conditions. Full article

The remediation of lead (Pb)-contaminated soils through eco-friendly strategies is critical for sustainable agriculture. This study investigated the role of arbuscular mycorrhizal fungi (AMF) in enhancing maize tolerance to Pb stress and modulating rhizosphere microbial communities. A pot experiment was conducted with maize (Baiyu833) under four Pb concentrations (0, 900, 1800, 2700 mg·kg⁻¹) and three AMF treatments: non-inoculation (Non), Funneliformis mosseae (Fm), or Rhizophagus intraradices (Ri). The results demonstrated that AMF inoculation significantly increased plant biomass, boosted antioxidant enzyme activities (SOD, POD), and reduced malondialdehyde (MDA) levels, mitigating Pb-induced oxidative stress. AMF restricted Pb translocation to aerial parts, with root Pb accumulation reaching 2110.76 mg·kg⁻¹ (Fm) and 2090.56 mg·kg⁻¹ (Ri) under Pb2700, enhancing phytostabilization. High-throughput sequencing revealed that AMF inoculation enriched α-diversity indices and restructured bacterial communities, favoring beneficial taxa like Promicromonospora, which are linked to heavy metal resistance and plant growth promotion. Principal coordinate analysis highlighted distinct clustering of microbial communities driven by AMF, emphasizing their role in alleviating Pb toxicity. These findings underscore that AMF enhance maize resilience to Pb by regulating antioxidant defense, immobilizing Pb in roots, and recruiting stress-tolerant rhizosphere microbiomes. This study provides insights into AMF-assisted phytoremediation as a sustainable strategy for Pb-contaminated soils. Full article

Grapevines (Vitis vinifera L.) face significant challenges from abiotic stresses caused by climate change, including drought, salinity, and temperature extremes. This comprehensive review examined the role of beneficial microorganisms in enhancing grapevine tolerance to these stresses, focusing on arbuscular mycorrhizal fungi (AMF), plant growth-promoting rhizobacteria (PGPR), and endophytes. The study analyzes species-specific effects and their molecular mechanisms, highlighting how single and consortium inoculations improve plant resilience. AMF species, particularly Funneliformis mosseae and Rhizophagus irregularis, demonstrated significant enhancement in drought and salinity tolerance through improved nutrient uptake and stress response modulation. The PGPRs, Bacillus and Pseudomonas species, show remarkable abilities to mitigate various abiotic stresses through mechanisms including phytohormone production and antioxidant defense enhancement. Endophytic microorganisms such as Pseudomonas fluorescens RG11 and Serendipita indica play crucial roles in stress mitigation through melatonin production and improved water retention, respectively. The synergistic effects of combined AMF, PGPR, and PGPF applications led to a significant increase in grapevine drought and salinity tolerance, improving nutrient uptake, photosynthesis rates, and antioxidant defense mechanisms. Molecular analysis revealed that these microbial consortia regulate the expression of stress-responsive genes, particularly VvNCED and VvP5CS, enhancing grapevine resilience through improved osmotic adjustment, ROS scavenging, and hormonal regulation. These findings provide valuable insights into the molecular pathways underlying stress tolerance, offering promising strategies for sustainable viticulture under climate change. Full article

Contaminants of emerging concern, such as pharmaceuticals (PhACs), are continuously introduced into agro-ecosystems through irrigation with treated wastewater (TWW). While this practice is increasingly common in drought regions, only limited information is available on the fate of PhACs within the soil–plant system. For this purpose, a two-year study was conducted by irrigating artichokes, non-inoculated and inoculated with different arbuscular mycorrhizal fungi, with water containing PhACs at different concentrations. The experiment, conducted in both open field and pot conditions, aimed to evaluate their potential accumulation in the soil and plant tissues. Results showed that PhACs concentrations varied according to the physicochemical properties of the compounds and the duration of irrigation. The study revealed minimal accumulation of contaminants in the soil and non-edible plant parts. This was observed only at the end of the second growing cycle, when the plants were irrigated with TWW containing trace PhAC levels. In contrast, during both pot cultivation cycles, PhACs accumulated in the soil were translocated into plant organs when irrigated with water enriched to 200 μg L⁻¹ with eight PhACs. At the end of the trial, climbazole had the highest concentration in soil, while carbamazepine and fluconazole showed greater accumulation across all plant organs compared to other PhACs. In both trials, plants inoculated with Septoglomus viscosum absorbed less PhACs compared to those inoculated with Rhizophagus irregularis + Funneliformis mosseae. These results suggest that, while the long-term use of TWW containing PhACs may improve artichoke yield, it could present different degrees of risk to both environmental and human health, depending on the concentration levels of contaminants. Full article

Rice serves as the staple food for half of the world’s population. Given the expanding global population, the urgency to allocate land for rice cultivation is paramount. In Northeast China, saline–sodic and black soils represent two distinct soil types used in rice production. During rice growth, soil microorganisms, including arbuscular mycorrhizal fungi (AMF), play pivotal roles in nutrient uptake and resistance to biotic and abiotic stressors. While numerous studies have elucidated the role of AMF in enhancing rice growth and its adaptation to stress, the differences in AMF communities within paddy fields between different soil types have been largely overlooked. In this study, high-throughput sequencing technology was employed to analyze the diversity and community structure of AMF, and metagenomic sequencing was employed to analyze AMF functional gene differences between the two soil types (black and saline–sodic soils). At the same time, the commonalities and differences of the soil characteristics (nitrogen, phosphorus, potassium, pH, etc.) were verified in influencing AMF communities. The results indicated that Glomus was the predominant genus in both soil types, followed by Paraglomus. The overall abundance of AMF was higher at the heading stage than at the harvest stage, with Paraglomus showing greater adaptation to the saline–sodic soil environment. Total phosphorus (TP) was identified as the primary factor influencing AMF diversity at the heading stage. In the harvest stage, AMF community diversity was greater in saline–sodic paddy soil compared to black soil, a reversal from the heading stage. Further analysis of the functional genes of Rhizophagus intraradices revealed that gene activity in the heading stage of saline soils significantly surpassed that in black soils, suggesting that R. intraradices plays a more crucial role in saline environments. Additionally, spore density and the content of easily extractable glomalin-related soil protein were relatively higher in saline–sodic soil than in black soil. Thus, it may be inferred that AMFs are more vital in saline–sodic soils than in black soils of the paddy fields in Northeast China. This study may offer valuable insights into the utilization of AMF in paddy fields in Northeast China. Full article

Potassium (K) plays important roles in plant growth and development processes, while low K (LK) stress inhibits plant growth by altering reactive oxygen species accumulation. Arbuscular mycorrhizal fungi (AMF) promote nutrient absorption and transport in plants. However, the roles of AMF in affecting K nutrition are less well studied than those of other nutrients, especially in wheat. In this study, the effects of AMF on four wheat varieties were evaluated; results showed that the inoculation with the AMF-Rhizophagus intraradices significantly increased mycorrhizal colonization, fresh and dry weights, ascorbic acid, and glutathione contents, while decreasing malondialdehyde contents under both normal and LK stress treatments. It is worth noting that the contents of K and several nutrient elements were more significantly increased in roots than in shoots, suggesting that AMF mainly affect the uptake of K and other nutrient elements in the roots. Moreover, the expression levels of K transporter genes were higher than those of nitrogen and phosphorus transporter genes, especially under AMF combined with LK stress treatments. These results indicate that AMF improves wheat growth and antioxidant activity by regulating K transporter gene expression and affecting K uptake and transport. Therefore, AMF could be used as a sustainable agricultural alternative in wheat under LK soils. Full article

Maize is considered to be one of the most significant crops in the world. On a global scale, the appropriate yield level of food can largely affect food security. During cultivation, this plant is exposed to many adverse environmental factors, including water deficiency. Plant stress is reduced by applying appropriate biostimulants or soil amendments. This study tested the effectiveness of preparations based on Rhizophagus irregularis, humic acids, Bacillus velezensis + Bacillus licheniformis and Methylobacterium symbioticum. The aim of the project was to assess the effect of selected microorganisms and substances on the growth, yield, and physiological parameters of maize. The hypothesis assumed that the preparations selected for this study could improve the condition of the plants in various soil moisture conditions. All treatments were carried out post-emergence. The experiments were conducted in greenhouse conditions, where, in conditions of different level of soil moisture, optimal and water deficiency, the effect of the above-mentioned substances and microorganisms on the height, mass of plants, and plant chlorophyll fluorescence was determined. Chlorophyll, anthocyanin, and flavonol content were also measured. In two-year field studies, the effect of the same preparations on plant height, grain yield, thousand-grain weight, oil, protein, and starch content in the grain was determined. It was shown that appropriately selected biostimulants have a positive effect on plant growth, physiological parameters, and the yield of maize grain. The impact of preparations on the grain yield depended on the conditions that prevailed in the growing season. 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

Arbuscular mycorrhizal fungi (AMF) are symbiotic fungi that associate with the vast majority of terrestrial plants. Among non-vascular plants, while AMF associations are well-documented in liverworts and hornworts, there is a broad consensus that symbiotic associations do not occur in mosses. Here, we report the presence of AMF in the living material of mosses found in Chaco Serrano (Tucumán, Argentina). We found all characteristic structures of AMF when establishing an intimate connection with two moss species of Pottiaceae (Bryophyta). While Gertrudiella uncinicoma exhibited AMF with both Arum- and Paris-type morphologies, Pleurochaete luteola only displayed an Arum-type morphology. Plant tissue samples were subjected to high-throughput sequencing for AMF identification. We determined that Rhizophagus irregularis was a clear dominant species in both moss species, with Glomus sp. also being present as a less abundant element. In addition, we also reported the presence of vesicles, arbuscules, and spores adhered to the hyphae and the presence of septate endophytes. This finding expands our understanding of the interactions between AMF and non-vascular plants and prompt us to further characterize this interaction by considering the diversity of mycorrhizal associations with concurrent implications for the ecology of mosses and the functionality of the ecosystems. Full article

Salt accumulation can degrade soil properties, decrease its productivity, and harm its ecological functions. Introducing salt-tolerant plant species associated with arbuscular mycorrhizal fungi (AMF) can act as an effective biological method for restoring salinized soils. AMF colonize plant roots and improve their nutrient acquisition capacity. However, there is limited knowledge on how AMF affects the production of signaling molecules, e.g., abscisic acid (ABA), salicylic acid (SA), and jasmonic acid (JA), related to plant–microbe interactions under salinity. Here, we assess the potential benefits of the AMF Rhizophagus intraradices in enhancing plant growth and nutrient uptake in addition to modulating stress hormone signaling levels (ABA, SA, and JA) of the facultative halophyte Sulla carnosa under saline conditions. Plants were grown in pots filled with soil and irrigated with 200 mM NaCl for 1 month. AMF symbiosis substantially increased the shoot dry weight (+107%), root dry weight (+67%), photosynthetic pigment content (chlorophyll a, chlorophyll b, and carotenoids), and nutrient uptake (C, N, P, K, Cu, and Zn) while significantly limiting the increase in the shoot Na⁺ concentration and H₂O₂ content caused by salinity stress. Mycorrhizal symbiosis significantly enhanced the root and shoot SA levels by 450% and 32%, respectively, compared to the stressed non-inoculated plants, potentially contributing to enhanced systemic resistance and osmotic adjustment under saline conditions. Salt stress increased the shoot ABA content, especially in R. intraradices-inoculated plants (113% higher than in stressed non-mycorrhizal plants). These findings confirm that AMF mitigated the adverse effects of salinity on S. carnosa by increasing the SA and ABA levels and reducing oxidative damage. Full article

Arbuscular mycorrhizal fungi (AMF) and phosphorus-solubilizing bacteria (PSB) play crucial roles in enhancing crop growth, increasing yields, and improving the soil microbial environment. The aim of this study was to investigate the effects of microbial inoculation and chlorothalonil on the AMF colonization rate in soybean roots, AMF spore density, nodule number, soybean biomass, and the composition of bacterial communities associated with soybean rhizosphere soil and AMF spores. The results indicated that the AMF colonization rate in soybean roots, AMF spore density, nodule number, and soybean biomass in the treatment inoculated with both Rhizophagus intraradices and Acinetobacter calcoaceticus were significantly greater than those in the other treatments. Inoculation with R. intraradices and A. calcoaceticus and spraying with chlorothalonil could influence the bacterial diversity in the rhizosphere soil of soybean. Compared with that in the control treatment, the relative abundance of Firmicutes in the rhizosphere soil of soybean plants inoculated with R. intraradices increased by 1.40%. In addition, both spraying with chlorothalonil and inoculation with A. calcoaceticus influenced the composition of AMF spore-associated bacterial communities. The relative abundance of Proteobacteria in AMF spore from soybean rhizosphere soil inoculated with R. intraradices and A. calcoaceticus increased by 12.42% compared to that in samples inoculated solely with A. calcoaceticus. This study provides a theoretical basis for microbial inoculation in improving the microenvironment of soybean rhizosphere soil and increasing soybean biomass. Full article

Sabkha (inland and coastal—saline beds or saline lands) are widespread in Saudi Arabia and are distinguished by their hypersaline nature. These hypersaline habitats are commonly covered by halophytic vegetation. Moreover, Arbuscular mycorrhizal fungi (AMF) are an essential component of these habitats and exhibit a unique adaptation and contribute significantly to ecosystem variability, diversity, and function. Additionally, AMF from saline habitats are an essential component for the successful rehabilitation of salinity-affected areas. Despite their importance, little is known about the distribution and abundance of AMF along inland and coastal sabkhat of Saudi Arabia. Therefore, the main objective of this study was to investigate the abundance and diversity of AMF in the coastal and inland sabkhat of Saudi Arabia. Five soil samples, each from five randomly selected spots (considering the presence of dominant and co-dominant halophytic species), were collected from every location and were used to assess the AMF abundance and diversity. The study indicated that the highest number of AMF spores was recorded from Jouf, averaging ≈ 346 spores 100 g⁻¹ dry soil, and the lowest from Uqair, averaging ≈ 96 spores 100 g⁻¹ dry soil. A total of 25 AMF species were identified, belonging to eight identified genera viz., Acaulospora, Diversispora, Gigaspora, Scutellospora, Claroideoglomus, Funneliformis, Glomus, and Rhizophagus and five families. Of the total identified species, 52% belonged to the family Glomeraceae. Moreover, the highest number of species was isolated from the sabkha in Qasab. Additionally, Glomeraceae was abundant in all the studied locations with the highest relative abundance in Uqair (48.34%). AMF species Claroideoglomus etunicatum, Funneliformis mosseae, Glomus ambisporum, and Rhizophagus intraradices were the most frequently isolated species from all the Sabkha locations with isolation frequency (IF) ≥ 60%, and Claroideoglomus etunicatum (Ivi ≥ 50%) was the dominant species in all the studied locations. Furthermore, data on the Shannon–Wiener diversity index showed that the highest AMF species diversity was in Qaseem and Qasab habitats. The highest Pielou’s evenness index was recorded in Jouf. Moreover, the soil parameters that positively affected the diversity of identified species included Clay%, Silt%, HCO₃¹⁻, OM, MC, N, and P, while some soil parameters such as EC, Na⁺, SO₄²⁻, and Sand% had a significant negative correlation with the isolated AMF species. This study revealed that AMF can adapt and survive the harshest environments, such as hypersaline sabkhas, and thus can prove to be a vital component in the potential restoration of salinity-inflicted/degraded ecosystems. Full article