Search Results (397)

Kentucky bluegrass powdery mildew, caused by the fungus Blumeria graminis f. sp. poae, is a destructive disease affecting Poa pratensis L. In this study, endophytic bacteria were isolated from the resistant Kentucky bluegrass cultivar ‘Taihang’. Employing a combination of conidia germination inhibition assays and control efficacy tests, the biocontrol endophytic bacterial strains were screened. The impact of inoculation with the powdery mildew pathogen and biocontrol endophytic bacteria on the difference in endophytic bacterial community in the leaves of Kentucky bluegrass were studied via Illumina Miseq high-throughput 16S ribosomal RNA gene sequencing technology. A total of 18 endophytic bacterial isolates were obtained from ‘Taihang’, belonging to 3 phyla: Proteobacteria (3 isolates), Actinobacteria (6 isolates), and Firmicutes (9 isolates). The conidia germination assay revealed that isolates 6213 (Bacillus sp.) and 718 (Neobacillus sp.) exhibited the strongest inhibitory against Blumeria graminis f. sp. poae, with inhibition rate exceeding 80%. Isolate 718 exhibited superior control efficacy over strain 6213. A concentration of 10⁹ colony-forming units per milliliter (CFU/mL) was the most effective in suppressing powdery mildew on Kentucky bluegrass. The abundance of Proteobacteria on Kentucky bluegrass after the application of isolate 718 may enhance the resistance of Kentucky bluegrass to powdery mildew, and the dominant endophytic bacterial communities were Burkholderiales, Burkholderiaceae and Cupriavidus, indicating that the application of isolate 718 modulated the plant’s response to powdery mildew infection. These results demonstrate that isolate 718 enhanced the resistance of Kentucky bluegrass against powdery mildew by reshaping the endophytic bacterial community within the leaves. These findings provide molecular insights into plant−pathogen−endophytic bacteria interactions and support the development of sustainable strategies, eco-friendly strategies for plant diseases management. Full article

Secondary metabolites produced by endophytic fungi living in medicinal plants are important resources in the field of biological control. In this study, Achaetomium sophora HY17, an endophytic fungus of Sophora alopecuroides, was taken as the research object and Botrytis cinerea HM1 as the target pathogen, and the response characteristics and antifungal mechanism of secondary metabolites produced during their interaction were explored through a co-culture system combined with metabonomic analysis. The key findings are as follows: (1) A. sophora HY17 produces many kinds of secondary metabolites, such as alkaloids, flavonoids, and phenolic acids, among which 10 different metabolites, such as Sophoridine, Matrine, and Luteolin, are significantly up-regulated during the interaction process and are the core antifungal active substances; (2) KEGG pathway enrichment analysis revealed that the phenylalanine metabolic pathway was significantly enriched during the interaction between the two fungi, and the activation of this pathway was the key regulatory mechanism underlying A. sophora HY17′s ability to cope with pathogen stress and synthesize antifungal metabolites. This study reports A. sophora HY17 as a new species, confirms its broad application prospects as a multifunctional and efficient biocontrol strain, and provides a core theoretical basis and target direction for mining antifungal substances from endophytic fungi to develop new biocontrol agents. Full article

Cercophora species, typically known as saprobes or coprophiles, have occasionally been isolated from healthy roots and have recently been recognized as endophytes. Their dark-pigmented structures suggest adaptation traits similar to dark septate endophytes, although their symbiotic potential remains unclear. This study isolated and characterized Cercophora sp. NPKC241 from mung bean roots grown under artificial drought in soils with different fertilization histories, using PCR-based DNA sequencing and morphological observation. Its effects on legume growth were subsequently evaluated through pot inoculation experiments under drought. These experiments focused on mung bean, a species known to exhibit significant reductions in chlorophyll content and yield under drought conditions. Among 29 isolates, Cercophora sp. consistently promoted legume growth. In mung bean, it increased shoot and root mass, chlorophyll content, and root elongation under both optimal and water-limited conditions. Under drought, inoculated plants showed approximately threefold higher chlorophyll levels, two- to threefold greater biomass, and roots approximately 5 cm longer than the control, indicating mitigation of drought-induced physiological decline. These findings suggest that Cercophora sp. can act as a beneficial root-associated fungus, enhancing legume performance under drought. Future studies will further explore this interaction by underlying physiological mechanisms and the field-level application potential. Full article

Lolium perenne L. (perennial ryegrass) has various applications, including as a high-quality forage species for livestock feed; in seed mixtures used for revegetation of eroded or degraded areas as well as for lawns due to its resistance and rapid germination; for erosion control on slopes and areas with excessive steepness; for phytoremediation of soils contaminated with potentially toxic elements due to its ability to accumulate metals in its tissues; and as a cover crop to improve soil conditions and control erosion. Accordingly, L. perenne provides several ecosystem services, primarily related to soil stability, agriculture, and recreation. Climate change poses challenges for L. perenne, particularly heat and drought stress, which can reduce its yield and alter its geographical distribution. Climate change also impacts the interactions between L. perenne and its environment, affecting aspects like phenology (e.g., flowering time), carbon fixation, and overall resilience. However, the species’ significant genetic and endophyte-related variability may allow for adaptation. The aim of the present study was to assess the drought tolerance of three Bulgarian varieties of L. perenne, namely Harmoniya (diploid), Tetrany, and Tetramis (tetraploids). We performed induced drought stress under laboratory conditions and monitored its effect on plants in the early stages of growth and development. A variety-specific response was found regarding the effect of different concentrations of sucrose on seed germination, primary root and stem elongation (cm), fresh biomass accumulation (g), as well as on seedling vigor index and plant development. Field experiments and yield elements were also used to assess drought susceptibility and sensitivity to stress in a real environment. The tetraploid perennial ryegrass varieties Tetrany and Tetramis showed better germination, growth, and development in laboratory tests and had higher and more stable field productivity under both optimal and stress conditions than the diploid variety Harmoniya. Ploidy was the factor that characterize them as drought-tolerant genotypes under water-limited conditions, and its potential could be used in future breeding programs. Full article

Plant–microbe interactions exert a significant influence on host stress responses; however, the molecular mechanisms underlying these effects remain inadequately understood. In this study, we characterize FaMAN8, an α-mannosidase from Fragaria × ananassa, to explore its role in adaptation to heat waves and water deficit, as well as its modulation by fungal endophytes. Transcriptomic analysis identified FaMAN8 as the sole α-mannosidase isoform highly conserved across reported sequences, with root-specific induction under conditions of heat stress, deficient irrigation, and endophytic colonization. Structural modeling revealed that FaMAN8 exhibits the canonical domain organization of glycoside hydrolase family 38 (GH38) enzymes, featuring a conserved catalytic architecture and metal-binding site. Molecular docking and dynamics simulations with the Man₃GlcNAc₂ ligand indicated a stable binding pocket involving key catalytic residues and strong electrostatic complementarity. MM-GBSA and free energy landscape analyses further supported the thermodynamic stability of the protein–ligand complex. Cavity analysis revealed a larger active site in FaMAN8 compared to its homolog JbMAN, suggesting broader substrate accommodation. Collectively, these findings identify FaMAN8 as a stress-responsive glycosidase potentially involved in glycan remodeling during beneficial root–fungus interactions. This work provides molecular insights into plant–microbe symbiosis and lays the groundwork for microbiome-informed strategies to enhance crop stress resilience. Full article

One open question regarding plant–microbe interactions is how a plant interacts molecularly with both a beneficial microbe and a pathogenic fungus. This study used RNA-seq to investigate molecular responses in maize roots during a tripartite interaction with the fungal pathogen Fusarium verticillioides (Fv), which causes stalk, ear, and root rot, and the endophytic biocontrol agent Bacillus cereus sensu lato B25, known to suppress Fv and promote plant growth. Roots of seven-day-old maize inoculated with Fv (Zm-Fv), B25 (Zm-B25), and co-inoculated (Zm-Fv-B25) were compared to uninoculated control (Zm). Differential Gene Expression (DEG), Gene Ontology (GO) and KEGG analysis revealed distinct molecular responses. Fv suppressed plant pathways related to DNA and protein synthesis and impaired root development. In contrast, B25 triggered defense priming and growth-related responses. In the co-inoculation experiment (Zm-B25-Fv), upregulated DEGs were associated with both defense-related metabolic pathways, including jasmonic acid signaling and secondary metabolite biosynthesis, and genes involved in plant growth processes. Co-expression networks using Arabidopsis orthologs supported the induction of defense- and growth and development-related genes. This study is the first RNA-seq analysis of maize root molecular responses during the tripartite interaction with a fungal pathogen and its bacterial biocontrol agent, providing new directions for further research to understand the detailed molecular mechanisms underlying this interaction fully. Full article

Numerous studies have shown that there are many uncertainties associated with the interactions of nitrogen with plants and microorganisms. In particular, the effects of symbioses between plants and various microorganisms on soil microbial community function remain unclear. Metagenomic sequencing was used to explore the changes in microbial community composition, function and metabolic pathways in rhizosphere soil and the associated influencing factors under different nitrogen levels caused by arbuscular mycorrhizal fungi (AMF) inoculation of F. rubra infected with endophytic fungi and nonendophytic fungi. Plant nutrient allocation (aboveground/belowground), soil pH, and enzymatic activities significantly modulated the functional profiles of the bacterial, fungal, and archaeal communities within these rhizospheres. Soil β-glucosidase activity had the greatest effect on the cluster of orthologous groups of proteins (COG) function of the rhizosphere soil bacterial community, and soil L-leucine aminopeptidase had the greatest effect on the COG function of the rhizosphere soil fungal and archaeal communities. The contributions of AMF colonization to the kyoto encyclopedia of genes and genomes (KEGG) functions of bacteria and archaea in the rhizosphere soil were greater than those of F. rubra infection with endophytic fungi, and AMF colonization improved the metabolic pathways, secondary metabolite biosynthesis, microbial metabolism, amino acid biosynthesis and carbon metabolism of bacterial and archaeal communities in the rhizosphere soil of F. rubra. The effects of endophytic fungi and AMFs on the function and metabolic pathways of symbiotic rhizosphere soil microbial communities were heterogeneous. This study revealed that considering both biotic and abiotic factors is essential for predicting the maintenance of soil ecosystem function by plant–fungal symbionts. Full article

With continuous increases in nitrogen (N) deposition in the future, its impacts on terrestrial ecosystems are attracting growing concern. Arbuscular mycorrhiza (AM) fungi play a crucial role in shaping both soil microbial and plant communities. AM fungi play a crucial role in shaping the soil microbial and plant communities, yet their patterns of influence under increased N deposition scenarios remain unclear, particularly in desert ecosystems. Therefore, we conducted a field experiment simulating increased N deposition and AM fungal suppression to assess the effects of increased N deposition and AM fungi on soil microbial communities, employing phospholipid fatty acid (PLFA) biomarker technology in the Gurbantunggut Desert of Xinjiang. We found that increased N deposition promoted soil microbial biomass, including AM fungi, fungi, Actinomycetes (Act), Gram-positive bacteria (G⁺), Gram-negative bacteria (G⁻), and Dark Septate Endophyte (DSE). AM fungal suppression significantly increased the content of soil Act and G⁺. There were clearly and significantly interactive effects of increased N deposition and AM fungi on soil microbial contents. Both increased N deposition and AM fungi caused significant changes in soil microbial community structure. Random forest analysis revealed that soil nitrate N (NO₃⁻-N), Soil Organic Carbon (SOC), and pH were main factors influencing soil microorganisms; soil AM fungi, G⁺, and Act significantly affected plant Shannon diversity; soil G⁻, Act, and fungi posed significant effects on plant community biomass. Finally, the structure equation model results indicated that soil fungi, especially AM fungi, were the main soil microorganisms altering the plant community diversity and biomass under increased N deposition. This study reveals the crucial role of AM fungi in regulating soil microbial responses to increased N deposition, providing experimental evidence for understanding how N deposition affects plant communities through soil microorganisms. Full article

Fusarium oxysporum f. sp. cubense (Foc), the causal agent of Fusarium wilt of banana, can persist in the soil for extended periods as chlamydospores or endophytes in weeds, complicating control measures. No single control strategy is effective. Biological agents present an increasingly important control option. This study explored the potential of the spent P. ostreatus substrates (SPoS) to suppress Foc R1 in a field with high Foc inoculum, following laboratory and greenhouse studies that highlighted the potential of P. ostreatus as a biocontrol agent against Foc. A susceptible cultivar ‘Sukali Ndizi’ and a resistant cultivar ‘Mpologoma’ were used for the study. SPoS was compared with farmyard manure (FYM), a combination of SPoS with FYM and a control without treatment. A one-time application of the treatments at planting did not consistently and significantly (p > 0.05) reduce the prevalence and severity of leaf symptoms, pseudostem splitting and corm damage in the mother and ratoon plants of the susceptible cultivar. No symptoms occurred in ‘Mpologoma’. SPoS applications at planting and after every two months over an 8-month period did not significantly reduce leaf symptoms and corm damage in ‘Sukali Ndizi’, while it increased pseudostem splitting. The marginal and irregular reductions in FW could be due to an observed high weevil damage in SPoS treatments and other confounding factors such as weather, SPoS quality, and pathogen load in the field. Further research on weevil–SPoS interactions, use of P. ostreatus mycelium-rich substrate, and other confounding factors is crucial for fine tuning P. ostreatus use. Full article

Plants inhabiting arid regions often harbor microbial communities that contribute to their resilience under extreme conditions. Yet, the genomic diversity and functional potential of bacterial endophytes associated with desert-adapted plants, particularly in Africa, remain largely unexplored. In this study, we investigated Microbacterium endophytes from the xerophytic cucurbit Citrullus colocynthis L. (Cucurbitaceae), collected in a semi-arid environment in central Morocco. Using culture-based isolation, phenotypic characterization, and whole-genome sequencing, we analyzed three representative isolates from leaf and root tissues. Genome-based taxonomy combined with polyphasic analyses identified two novel species, Microbacterium xerophyticum sp. nov. and Microbacterium umsixpiens sp. nov., with genome sizes of approximately 4.0 Mb and 3.9 Mb, respectively. Functional annotation revealed traits consistent with endophytism in water-limited ecosystems, including oxidative and osmotic stress responses, metal homeostasis, and high-affinity phosphate uptake. Differences in siderophore acquisition and nitrogen metabolism suggest niche partitioning between the two species. These findings document two novel bacterial species from a medicinal plant native to arid ecosystems, broaden the known diversity of plant-associated Microbacterium, and provide region-specific genomic references with adaptive traits relevant to host resilience under arid conditions. Full article

Drought and salt stresses are critical environmental constraints affecting plant growth and development, and microorganisms can enhance plant tolerance to these abiotic stresses through complex mechanisms. This review systematically synthesizes the core mechanisms by which microorganisms regulate plant physiological and biochemical processes under such stresses, specifically including the following: (1) regulating the perception and transduction of abiotic stress signals to enhance plant adaptive responses; (2) boosting gene expression and protein synthesis for overall plant metabolic regulation; (3) activating the antioxidant system to strengthen plant tolerance; (4) modulating plant hormone levels to stimulate growth in response to adversity; (5) enhancing plant nutrition and absorption to improve resilience; (6) optimizing the photosynthesis system to promote the synthesis of essential substances, safeguarding plant growth and development amidst adversity. Finally, the application of microbial inoculants in saline–alkali soil improvement and crop cultivation in arid areas and prospective research directions are discussed. Full article

The intricate connections between plants and the microbial populations that surround them are crucial for plant development and resilience, but little is known about the evolutionary processes influencing these partnerships. Less is known about how pathogenic and beneficial microbes coevolve with their plant hosts over ecological and evolutionary timeframes, despite the fact that several studies identify rhizosphere and endophytic microbes that support nutrient acquisition, disease resistance, and stress tolerance. Using molecular, ecological, and evolutionary investigations from soil, rhizosphere, and endosphere habitats, this review summarizes current findings on microbial coevolution in plant–microbe systems. We look at the endosymbiotic processes that underlie the development of organelles, the mechanisms of mutualism and antagonism, and the eco-evolutionary feedbacks that affect plant health and agricultural output. The inadequate comprehension of intraspecific microbial diversity, the application of laboratory coevolution experiments to field settings, and the long-term effects of climate change on the evolutionary dynamics of plants and microbiomes are some of the major knowledge gaps. When pathogenic and beneficial microbes apply selective pressures to one another and their common host, coevolution takes place. This results in mutual genetic and physiological adaptations, such as modifications to host immunity, microbial virulence, or competitive tactics, which influence the way the two types interact over time. We conclude that understanding plants as holobiont-integrated units of hosts and their microbiomes offers fresh chances to develop microbiome-based approaches to sustainable agriculture, such as coevolutionary breeding programs, precision biofertilizers, and resilient cropping systems. Full article

In mycorrhizal symbiotic relationships, non-photosynthetic myco-heterotrophic plants are unable to supply photosynthates to their associated fungi. On the contrary, they rely on fungal carbon to sustain their own growth. Mycorrhizal fungi can mediate plant interactions with the rhizosphere microbiome, which contributes to the promotion of plant growth and nutrient uptake. However, the microbial community and key microbial species that function during the growth of the myco-heterotrophic plant Cheilotheca humilis remain unclear. In this study, we evaluated the microbial community associated with Cheilotheca humilis, which was confirmed via morphological characteristics typical of this plant species. Metagenomic analysis showed that the Afipia carboxidovorans was dominant at species level. Based on the LDA score, Bradyrhizobium ottawaense exhibited the higher abundance in the CH-B group (related to bud) while Afipia carboxidovorans was identified from the CH-F group (related to flower). Microbial co-occurrence networks showed that the Rhizobium genus, Herbaspirillum genus, and Cyanobacteriota were defined as core functional microbial species. To explore the potential microorganisms, metagenome-assembled genomes (MAGs) of the rhizosphere microbiome identified 14 medium- and high-quality MAGs, mainly involved in carbon fixation, nitrogen transformation, and phosphorus metabolism, possibly providing nutrients for the plant. Furthermore, a total of 67 rhizospheric and 66 endophytic microorganisms were isolated and obtained. In vitro experiments showed that the mycorrhizal helper bacteria (MHBs) Rhizobium genus and Pseudomonas genus possessed the ability of nitrogen fixation, phosphate solubilization, and siderophores production. Most importantly, the mycorrhizal fungus Humicolopsis cephalosporioides was obtained, which could potentially produce cellulase to supply carbohydrates for host. The findings suggest the mycorrhizal fungus Humicolopsis cephalosporioides and helper bacteria have great potential in the growth of the myco-heterotrophic plant Cheilotheca humilis. Full article

Soybean inoculation with nitrogen (N) fixing bacteria can be highly promising for enhancing biological nitrogen fixation (BNF) and improving crop productivity. It helps to reduce dependency on chemical fertilizers, promotes sustainable agricultural practices, and minimizes environmental impacts. Therefore, understanding the specific aspects and conditions is essential for establishing the BNF process in particular environments. In this study, we investigated whether soybean inoculation is an effective strategy in cool-climate regions beyond their typical northern distribution, and which soybean varieties and microbial strains are the most effective for optimizing soybean productivity and performance in relatively cool environments. To address these questions, a natural abundance nitrogen stable isotope ratio analysis was conducted on two soybean varieties of different maturity groups, which were inoculated with three Bradyrhizobium japonicum strains, along with organic fertilizer and new promising endophyte treatments. This approach aimed to determine the differences in biological and chemical parameters of soybean, as well as the origin of N sources, its uptake, and the isotopic distribution within the plants. It was demonstrated that inoculation with Bradyrhizobium japonicum was more effective than fertilization, as the strains had a significant effect on nitrogen derived from the atmosphere (Ndfa), produced stable nitrogen isotope ratios close to 0‰, and substantially increased nitrogen content, particularly in beans. Soybean varieties Laulema and Merlin, representing different maturity groups, exhibited distinct nitrogen uptake patterns. Bradyrhizobium japonicum strain AGF78 consistently produced the greatest effect on biological parameters in both varieties, particularly in seed yield and grain weight, with the later-maturing Merlin achieving the highest average yield of 3066.89 kg ha⁻¹. Notably, the Merlin inoculated with AGF78 resulted in the highest nitrogen fixation in beans, with 66.8%NDFA and 134.0 kg/ha of fixed nitrogen. Similarly, Laulema inoculated with AGF78 resulted in 88.2%NDFA and 123.2 kg/ha of fixed nitrogen. Inoculation with selected bacterial strains significantly increased protein content from 30% to 41%, with the effects being both strain- and variety-specific. Our study showed that establishing effective soybean–microbe interactions by choosing soybean variety and microbial strain is crucial for optimizing agricultural practices and improving crop performance, especially in sustainable and environmentally conscious farming systems under cool climatic conditions of Europe. Full article

The long-term application of traditional chemical herbicides has caused a significant escalation in herbicide resistance of barnyard grass (Echinochloa crus-galli). As an eco-friendly alternative, biological herbicides demonstrate substantial application potential. Acknowledging the growing herbicide resistance of E. crus-galli, this study aimed to screen target bacteria with inhibitory effects on the growth for bio-herbicide development. By using ungerminated E. crus-galli seeds as the screening substrate, a bacterial strain (BFYBC-8) with potent inhibitory activity was isolated and identified as Brucella pseudorignonensis. Pot experiments revealed that inoculation with B. pseudorignonensis BFYBC-8 significantly suppressed E. crus-galli growth, reducing plant height by 16.7% and root length by 85.1%, while markedly inhibiting biomass accumulation. Fluorescent labeling with green fluorescent protein (GFP) showed that BFYBC-8 successfully colonized the root intercellular spaces of E. crus-galli and extended continuously along the tissue matrix. Additionally, the strain’s supernatant metabolic products exhibited exceptional thermostability: inhibitory activity against E. crus-galli was maintained after thermal treatment at 28 °C, 60 °C, 80 °C, and 100 °C. Crucially, the bacterium displayed no toxicity to agronomically important crops such as rice, wheat, and corn. This study highlights B. pseudorignonensis BFYBC-8 as a promising candidate for bioherbicide development and provides an important reference for applying seed-associated pathogenic bacteria in developing bioherbicides for sustainable weed management. Full article