Search Results (174)

Plant endophytes, often termed the “second genome”, critically shape host adaptability. However, the complexity of their interactions, regulated by microbial traits, host species, and environment, has limited both our understanding of symbiosis and the application of beneficial endophytes. The symbiosis between locoweeds (Oxytropis and Astragalus species) and the endophyte Alternaria sect. Undifilum, which produces the neurotoxin swainsonine, serves as an ideal model for investigating these relationships. Through extensive national surveys (2021–2023) across China’s major locoweed habitats, combining field sampling with cultivation, molecular, quantitative, and modeling approaches, a central question emerged: To what extent are the distribution and function of this symbiosis shaped by the contemporary environment versus host evolutionary history? The results showed that: (1) Among 32 surveyed species of Oxytropis, Astragalus, and Sphaerophysa, the endophyte Alternaria sect. Undifilum colonized 11 species. In colonized plants, endophyte loads ranged from 0.02 to 58.87 pg/ng total DNA, and swainsonine concentrations varied from 0.00003% to 1.00%. (2) Environmental factors, rather than host phylogeny, were the key driver governing the geographical distribution and expression of the symbiosis. (3) Low temperature and drought stress regulated the symbiotic relationship and chemical defense through both direct effects on the symbionts and indirect pathways involving grazing pressure. This study demonstrates that the environment is the core force dominating the geographical pattern and functional expression of the locoweed–endophyte symbiosis at ecological scales. These findings provide new perspectives for understanding the general principles of plant–endophyte symbiosis and establish a scientific foundation for predicting and utilizing endophyte resources in changing environments. Full article

Rice blast, caused by the fungal pathogen Pyricularia oryzae, remains one of the most destructive diseases threatening global rice production. Although the deployment of resistant cultivars is widely regarded as the most effective and sustainable control strategy, resistance based solely on host genetics often has limited durability due to the rapid adaptation of the pathogen. Increasing evidence suggests that plant-associated microbial communities contribute to host health and disease resistance, yet the role of seed-associated microbiota in shaping rice blast resistance remains insufficiently understood. In this study, we investigated seed endophytic bacterial communities across multiple indica–japonica hybrid rice varieties from the Yongyou series that exhibit contrasting levels of resistance to rice blast. By integrating amplicon sequencing, we identified distinct seed bacterial assemblages associated with blast-resistant and blast-susceptible varieties were identified. Notably, the microbial communities in blast-resistant varieties exhibited significantly higher Shannon index, with a median value of 3.478 compared to 2.654 in susceptible varieties (p < 0.001), indicating a greater diversity and more balanced community structure compared to those in susceptible varieties. Several bacterial taxa consistently enriched in resistant varieties showed negative ecological associations with P. oryzae, both at the local scale and across publicly available global metagenomic datasets. These findings indicate that seed endophytic bacterial communities are non-randomly structured in relation to host resistance phenotypes and may contribute to rice blast resistance through persistent ecological interactions with the pathogen. This work highlights the potential importance of seed-associated microbiota as intrinsic components of varietal resistance and provides a microbial perspective for improving durable disease resistance in rice breeding programs. Full article

The olive tree hosts diverse endophytic fungi that may contribute to plant protection and growth. In this study, a preliminary screening of olive-associated fungal endophytes was conducted. A total of 67 fungal endophytes were isolated from the leaves and roots of the Greek cultivars Amfissa and Kalamon and identified using morphological and molecular approaches; 28 representative strains were selected for functional evaluation. Dual culture assays revealed substantial antagonistic activity against major phytopathogens, with growth inhibition ranging from 19.05% to 100%. Notably, strains F.KALl.8 and F.AMFr.15 showed the strongest suppression across pathogens. Interaction phenotyping revealed all major interaction types (A, B, C) and subtype C1/C2, with several strains producing pigmentation zone lines or hyphal ridges at contact sites. The assessment of plant growth-related effects using Arabidopsis thaliana as a model system showed that three strains (F.AMFr.15, F.KALr.4, F.KALr.38A) significantly increased seedling biomass (up to ~16% above the control), whereas nine strains caused severe growth reduction and disease symptoms. Beneficial strains also altered root architecture, inhibiting primary root elongation while inducing extensive lateral root formation. Collectively, these findings highlight the functional diversity of olive-associated fungal endophytes and identify promising candidate strains, particularly F.AMFr.15 (identified as Clonostachys sp.), for further host-specific validation as potential biological control and plant growth-promoting agents. 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

Epichloë is a genus of endophytic fungi that forms systemic, vertically transmitted, and asymptomatic mutualistic associations with grasses in the subfamily Pooideae. These symbioses are non-pathogenic and are of considerable importance in agronomic and livestock systems due to their roles in enhancing host fitness under biotic and abiotic stress. Several studies have reported associations between Epichloë endophytes and species of the genus Bromus, a taxonomically complex group characterized by varying ploidy levels and frequent hybridization. Among its sections, Bromopsis includes the highest number of species naturally colonized by Epichloë fungi, while sections Bromus and Ceratochloa show lower infection rates. In South America, endophytes such as E. pampeana, E. tembladerae, E. typhina, and morphotypes of Neotyphodium spp. have been documented in species including B. auleticus, B. brachyanthera, and B. setifolius, where they appear to contribute to stress resilience. Although most findings originate from Argentina, significant knowledge gaps remain regarding the diversity and distribution of these endophytes in native Bromus species across the continent. This review synthesizes the current understanding of Epichloë–Bromus interactions, emphasizing their ecological and agronomic relevance, particularly in South America. Key factors influencing the establishment of these symbioses are examined, and future research directions are proposed to advance the study of these associations. 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

The plant microbiome plays a pivotal role in host development and resilience against biotic and abiotic stresses. In perennial crops like peach, microbial communities inhabiting dormant buds—critical yet vulnerable organs—may influence disease outcomes and plant fitness. This study characterized the bacterial and fungal communities associated with the buds of three peach cultivars differing in susceptibility to Twig Canker and Shoot Blight (TCSB). Amplicon-based profiling revealed distinct microbiome signatures across cultivars, shaped by host genotype. The highly tolerant ‘Catherina’ harbored a structured and relatively diverse community enriched in beneficial bacterial genera such as Pseudomonas, Sphingomonas, and Curtobacterium, alongside protective yeasts including Aureobasidium and Cladosporium. In contrast, the susceptible cultivar ‘Pavoro^®-Pav 1605’ hosted a less balanced microbiome, marked by enrichment of opportunistic pathogens such as Alternaria and Diaporthe, as well as the bacterial lineage 1174-901-12. The intermediate cultivar ‘Lami^®.COM’ displayed a transitional profile enriched in Sphingomonas, Pelomonas, and Vishniacozyma. Differential abundance analyses confirmed cultivar-specific enrichment patterns, underscoring the influence of genotype in shaping microbiota composition and potential disease outcomes. These findings support the integration of microbiome-based approaches into sustainable disease management via beneficial microbial promotion, early detection of harmful consortia, and microbiome-informed breeding to foster resilient, low-input peach cultivation systems. Full article

Halotolerant endophytic fungi (HEFs) represent a critical biological resource in mitigating plant salt–alkali stress, demonstrating remarkable adaptability across diverse ecological environments. This comprehensive review analyzes 150 scientific publications, revealing HEFs’ multifaceted mechanisms of plant stress tolerance. Inhabiting over 30 host plant species without causing pathogenic effects, these fungi enhance plant resilience through sophisticated physiological strategies. Key findings highlight HEFs’ ability to modulate ionic homeostasis, elevate antioxidant capacities, and stimulate plant growth under saline conditions. The research unveils the potential of HEF metabolites as biostimulants and explores their co-evolutionary hypotheses with host plants. Despite promising laboratory and field validations, significant challenges remain in HEFs’ practical agricultural applications, including environmental factor interactions and biotechnological ethical considerations. Future research directions emphasize deeper investigations into HEFs’ ecological adaptability and microbiological interactions to unlock their full agricultural potential. Full article

Bacterial endophytes have emerged as critical components of plant microbiomes, offering multifaceted benefits ranging from growth promotion to stress resilience. This review synthesizes two decades of research, from 2004 to 2024, on bacterial endophyte identification and applications, highlighting advances in both traditional culture-based techniques and modern omics approaches. The review also focuses on interactions between these microorganisms and their host plants, emphasizing their roles in biocontrol, phytoremediation, and nanoparticle biosynthesis. While significant progress has been made in characterizing cultivable bacterial endophytes, challenges persist in accessing unculturable species and understanding strain-specific functional mechanisms. The integration of metagenomics, metatranscriptomics, and metabolomics has begun unraveling this hidden diversity, revealing novel metabolic pathways and plant–microbe communication systems. There have been limitations in endophyte isolation protocols and field applications, and therefore a need exists for standardized frameworks to bridge lab-based discoveries with agricultural practices. Cutting-edge multi-omics techniques, such as genomics, transcriptomics, metabolomics, proteomics, and phenomics, should be used more in future research to clarify the mechanistic underpinnings of plant–endophyte interactions to thoroughly profile the microbial communities and unlock their functional potential under diverse environmental conditions. Overall, bacterial endophytes present viable paths toward sustainable farming methods, supporting food security and crop resilience in the face of environmental difficulties by providing a transformative opportunity for next-generation agriculture, mitigating climate-related agricultural stressors, reducing dependence on synthetic agrochemicals, and enhancing crop productivity. Full article

Botryosphaeria dothidea is the causative agent of Chinese hickory trunk canker, which poses significant threat to the production of Chinese hickory (Carya cathayensis Sarg.). Previous studies reported that endophytic–pathogenic phase transition, also referred to as latent infection, plays an important role in the interaction of Botryosphaeria dothidea with various host plants, including Chinese hickory. However, the mechanism underlying this phase transition is not well understood. Here, we employed RNA-Seq to investigate transcriptional changes in B. dothidea during its phase transition upon interaction with Chinese hickory. A co-expression network was generated based on 6391 differentially expressed genes (DEGs) identified from different infection stages and temperature treatments. One co-expressed module was found that highly correlated with temperature treatments which simulated conditions of B. dothidea latent infection in the field. Subsequently, 53 hub genes were detected, and gene ontology (GO) enrichment analysis revealed three categories of enriched GO terms: transmembrane transport or activity, ion homeostasis or transport, and carbohydrate metabolism. One PacC transcriptional factor (BDLA_00001555, an ambient pH regulator), and one endo-β-1,3-glucanase (BDLA_00010249) were specifically upregulated under temperature treatments that corresponded with the activation stage of B. dothidea’s pathogenic state. The knockout mutant strain of BDLA_00001555 demonstrated defective capability upon the activation of the pathogenic state. This confirmed that BDLA_00001555, the PacC transcriptional factor, plays an important role in the latent infection phase of B. dothidea. Our findings provide insights into the pathogenic mechanism of Chinese hickory trunk canker disease. Full article

Plant microbiomes are vital for the growth and health of their host. Tree-associated microbiomes are shaped by multiple factors, of which the host is one of the key determinants. Whether different host genotypes affect the structure and diversity of the tissue-associated microbiome and how specific taxa enriched in different tree tissues are not yet well illustrated. Chinese fir (Cunninghamia lanceolata) is an important tree species for both economy and ecosystem in the subtropical regions of Asia. In this study, we investigated the tissue-specific fungal community structure and diversity of nine different Chinese fir genotypes (39 years) grown in the same field. With non-metric multidimensional scaling (NMDS) analysis, we revealed the divergence of the fungal community from rhizosphere soil (RS), fine roots (FRs), and thick roots (TRs). Through analysis with α-diversity metrics (Chao1, Shannon, Pielou, ACE, Good‘s coverage, PD-tree, Simpson, Sob), we confirmed the significant difference of the fungal community in RS, FR, and TR samples. Yet, the overall fungal community difference was not observed among nine genotypes for the same tissues (RS, FR, TR). The most abundant fungal genera were Russula in RS, Scytinostroma in FR, and Subulicystidium in TR. Functional prediction with FUNGuild analysis suggested that ectomycorrhizal fungi were commonly enriched in rhizosphere soil, while saprotroph–parasite and potentially pathogenic fungi were more abundant in root samples. Specifically, genotype N104 holds less ectomycorrhizal and pathogenic fungi in all tissues (RS, FR, TR) compared to other genotypes. Additionally, significant correlations of several endophytic fungal taxa (Scytinostroma, Neonothopanus, Lachnum) with the growth traits (tree height, diameter, stand volume) were observed. This addresses that the interaction between tree roots and the fungal community is a reflection of tree growth, supporting the “trade-off” hypothesis between growth and defense in forest trees. In summary, we revealed tissue-specific, as well as host genotype-specific and genotype-common characters of the structure and functions of their fungal communities. Full article

Perennial ryegrass (Lolium perenne), an important forage and turfgrass species, can establish a mutualistic symbiosis with the fungal endophyte Epichloë festucae var. lolii. Although the physiological and ecological impacts of endophyte infection on ryegrass have been extensively investigated, the response of the soil microbial community and nitrogen-cycling gene to this relationship has received much less attention. The present study emphasized abundance and diversity variation in the AOB-amoA, nirK and nosZ functional genes in the rhizosphere soil of the endophyte–ryegrass symbiosis following litter addition. We sampled four times: at T₀ (prior to first litter addition), T₁ (post 120 d of 1st litter addition), T₂ (post 120 d of 2nd litter addition) and T₃ (post 120 d of 3rd litter addition) times. Real-time fluorescence quantitative PCR (qPCR) and PCR amplification and sequencing were used to characterize the abundance and diversity of the AOB-amoA, nirK and nosZ genes in rhizosphere soils of endophyte-infected (E+) plants and endophyte-free (E−) plants. A significant enhancement of total Phosphorus (P), Soil Organic Carbon (SOC), Ammonium ion (NH₄⁺) and Nitrate ion (NO₃⁻) contents in the rhizosphere soil was recorded in endophyte-infected plants at different sampling times compared to endophyte-free plants (p ≤ 0.05). The absolute abundance of the AOB-amoA gene at T₀ and T₁ times was higher, as was the absolute abundance of the nosZ gene at T₀, T₁ and T₃ times in the E+ plant rhizophere soils relative to E− plant rhizosphere soils. A significant change in relative abundance of the AOB-amoA and nosZ genes in the host rhizophere soils of endophyte-infected plants at T₁ and T₃ times was observed. The experiment failed to show any significant alteration in abundance and diversity of the nirK gene, and diversity of the AOB-amoA and nosZ genes. Analysis of the abundance and diversity of the nirK gene indicated that changes in soil properties accounted for approximately 70.38% of the variation along the first axis and 16.69% along the second axis, and soil NH₄⁺ (p = 0.002, 50.4%) and soil C/P ratio (p = 0.012, 15.8%) had a strong effect. The changes in community abundance and diversity of the AOB-amoA and nosZ genes were mainly related to soil pH, N/P ratio and NH₄⁺ content. The results demonstrate that the existence of tripartite interactions among the foliar endophyte E. festucae var. Lolii, L. perenne and soil nitrogen-cycling gene has important implications for reducing soil losses on N. Full article

Plant–endophyte symbioses are widespread in grasslands. While symbiotic interactions often provide hosts with major fitness enhancements, the role of the endophyte Alternaria oxytropis, which produces swainsonine in locoweeds (Oxytropis and Astragalus spp.), remains enigmatic. We compared endophyte-infected (E+) and endophyte-free (E−) plants of three main Chinese locoweed species (O. kansuensis, O. glabra, and O. ochrocephala) under controlled conditions, and analyzed environmental factors at locoweed poisoning hotspots for herbivores. The results demonstrated significant species-specific effects: E+ plants of O. glabra and O. ochrocephala exhibited 26–39% reductions in biomass, net photosynthetic rate, and stomatal conductance, with elevated CO₂ levels, while O. kansuensis showed no measurable impacts. Swainsonine concentrations were 16–20 times higher in E+ plants (122.6–151.7 mg/kg) than in E− plants. Geospatial analysis revealed that poisoning hotspots for herbivores consistently occurred in regions with extreme winter conditions (minimum temperatures ≤ −17 °C and precipitation ≤ 1 mm during the driest month), suggesting context-dependent benefits under abiotic stress. These findings suggest that the ecological role of A. oxytropis may vary depending on both host species and environmental context, highlighting a trade-off between growth costs and potential stress tolerance conferred by A. oxytropis. The study underscores the need for field validation to elucidate the adaptive mechanisms maintaining this symbiosis in harsh environments. Full article

Despite chemical exchange often serving as the first step in plant–microbe interactions, the specialized chemical metabolites produced by grass–Epichloë endophyte symbiosis as mediators of host growth, nutrient acquisition, and modulators of the rhizosphere community under low-nitrogen conditions are areas lacking in knowledge. In this study, we investigated the plant growth-promoting effects of the Epichloë endophyte strain and identified the growth of the Epichloë strain under different types of nitrogen source treatments. In addition to the in vitro test, we evaluated growth performance for Epichloë endophyte–infected plants (E+) and Epichloë endophyte–free plants (E−) in a pot trial under 0.01 mol/L urea treatment. Seedlings from E+ and E− groups were collected to analyze the plant bacterial microbiome and root metabolites. The E. gansuensis endophyte strain was found not to produce indoleacetic acid (IAA), pectinase, or contain ferritin. The nitrogenase gene, essential for nitrogen fixation, was also absent. These results suggest that E. gansuensis endophyte strains themselves do not contain attributes to promote plant growth. Concerning N fertilization, it was observed an increase in the colony diameter of E. gansuensis strain was observed only in the NO₃⁻-N (NN) treatment, while inhibition was observed in the urea-N (UN) treatment. E. gansuensis endophyte symbiosis significantly increased tiller number and plant dry weight. Overall, our results suggest that the E+ plants had more root forks and greater average root diameter compared to E− plants under the UN treatment. In a pot experiment using UN, data from 16S rRNA amplicon sequencing revealed that E. gansuensis endophyte infection significantly altered the bacterial community composition in shoot and root, and significantly increased Shannon (p < 0.001) and Chao 1 (p < 0.01) indexes. The relative abundance of Acidobacteriota, Actinomycetota, Cyanobacteriota, Fibrobacterota, Myxococcota, and Patescibacteria in the shoot, and Cyanobacteriota, Pseudomonadota, and Verrucomicrobiota in the root were significantly increased by E. gansuensis endophyte infection. Similarly, E. gansuensis endophyte symbiosis shifted the metabolite composition of the host plants, with the E+ plants showing a higher number of metabolites than the E− plants. In addition, co-metabolism network analysis revealed that the positive relevance between exudates and microorganisms in the root of the E+ plants is higher than that of the E− plants. These findings provide valuable insights into the knowledge of the effects of the symbiotic relationship between host plants and Epichloë endophyte on interspecific interactions of plant microbiome, beneficial for harnessing endophytic symbiosis, promoting plant growth. Full article