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Premise of research. Species-level variation in interactions with root-associated microbial communities has its evolutionary origins within species, where dissection of the mechanistic basis of plant divergence is also tractable. We use montane annual and coastal perennial populations (ecotypes) of Mimulus guttatus (yellow monkeyflower) to ask whether and how plant-microbe-soil interactions have diverged between populations with distinct life histories. Methodology. We characterized fungal communities in representative montane annual (Iron Mountain) and dune perennial (Florence dunes) habitats in Oregon, where previous reciprocal transplants revealed local adaptation. We then investigated how plant ecotype, microbial source, and soil origin affected plant performance and root-associated fungal communities in a full-factorial greenhouse experiment using plants, soils, and nested inocula (sterilized, filtered to remove arbuscular mycorrhizal fungi, and whole) from the two sites. Pivotal results. In the field, coastal perennial and montane annual monkeyflowers harbored distinct fungal communities, and perennial roots were enriched for mutualistic taxa relative to local soils. In the greenhouse common garden, microbial effects were largely negative (particularly in the annual ecotype), and there was no evidence of plant local adaptation to belowground conditions. However, the coastal perennial ecotype was more colonized by arbuscular mycorrhizal fungi than the montane annual ecotype, and it preferentially recruited local arbuscular mycorrhizal fungi taxa even when inoculated from the montane source. Conclusions. Our results suggest that population divergence in life history and related traits shapes plant responsiveness to soil microbes and the specificity of their associations with root endophytic fungi, such as arbuscular mycorrhizal fungi. Complex belowground effects on plant performance do not fit a simple pattern of local adaptation but may be by-products of other drivers of plant divergence. This work advances the study of heritable variation in plant-soil-microbe interactions in a model species for understanding the genomics of plant adaptation. [ABSTRACT FROM AUTHOR]

BACKGROUND AND OBJECTIVES: Falcataria moluccana is a potential forest tree species with high economic value in Indonesia, and it is widely planted in various forests and landscape restorations. F. moluccana planting has declined in productivity due to decreased site quality and pest and disease attacks. Dark septate endophytes are a group of root endophytic fungi that have potential as biological control and promoter agents. This research aims to test the symbiotic potential of several dark septate endophytes isolates, to determine the effect of dark septate endophytes on the germination of F. moluccana seeds, and what types of secondary metabolites are produced from this symbiotic interaction. METHODS: Three dark septate endophytes isolates, i.e., Rhizopycnis vagum, Curvularia sp., and Dendrothyrium sp. were used in this study. Those isolates were inoculated on the seeds of F. moluccana and observed the endophytism and metabolite compounds produced after 23 hours and 14 days of inoculation time.FINDINGS: Three new findings of this study were: 1) the dark septate endophytes isolates, i.e., Rhizopycnis vagum, Curvularia sp., and Dendrothyrium sp. could colonize F. moluccana seeds on the surface with a colonization rate of 96 percent, 32.5 percent, and 100 percent, and entered the seed tissue and the sprout roots with a colonization rate of 93.3 percent, 93.3 percent, and 70 percent. The dark septate endophytes colonization could be seen at the beginning of germination, inoculation of 0-23 hours, and after germination until observation at the age of 14 days; 2) The dark septate endophytes has the potential to improve seed germination and vigor of F. moluccana, by speeding up the germination process and increasing the vigor index, this condition is expected to produce seeds that can grow and survive environmental stress; 3) The dark septate endophytes has the potential to trigger an increase secondary metabolite compounds in F. moluccana seeds, which can be as antibacterial, antifungal, and antioxidants such as the Hexamethyl Cyclotrisilaxane compound, 1-Isopropenyl-4-methyl-1,3-cyclohexadiene, and Acetamide, 2, 2,2-trifluoro-N-methyl-N- (trimethylsilyl) as a form of plant protection when the F. moluccana seeds grew and developed to be a normal seedling. These conditions are believed to produce high-quality seedlings that can grow and adapt well to their new environment after being outplanted. CONCLUSION: Dark septate endophytes colonization of F. moluccana seeds does not reduce seed viability, so dark septate endophytes inoculation of seeds can be used as a seed treatment and can produce healthy and vigorous F. moluccana seedlings, thereby increasing the success of planting in the context of restoration of degraded forest and landscape.

Bacterial leaf streak disease, or black chaff, is one of the most important and damaging diseases of wheat worldwide. The impact of the disease on wheat and cereal production is increasing due to the lack of information and proper management methods to control it. Therefore, to develop an effective approach for managing this disease, the present study assessed the capability of fourteen strains of endophytic fungi to control this disease in laboratory and greenhouse conditions. The laboratory results revealed that volatile compounds produced by endophytic fungi significantly impacted the growth of pathogenic bacteria compared to the control. Furthermore, the greenhouse results indicated that all endophytic fungi significantly reduced the disease severity. A strain of Pleosporales sp. showed the highest efficiency in reducing disease severity, with a reduction of 59.03% compared to the infected control. Additionally, Fusarium moniliforme, Trichoderma virens, Trichoderma aerugineum, Clonostachys rosea, Arthrinium arundinis, and Epicoccum nigrum species showed favorable efficiency, reducing disease severity by 50.62%, 49.69%, 48.45%, 47.71%, 41.71%, and 41.67% respectively compared to the infected control. Furthermore, analysis of variance and mean comparison revealed that the effect of endophytic fungi on wheat growth parameters were strain depended. This report is the first to investigate the impact of various endophytic fungi on the control of bacterial leaf streak in wheat. In conclusion, endophytic fungi have great potential to be incorporated into the integrated management of Black Chaff disease and enhance the growth parameters of wheat. [ABSTRACT FROM AUTHOR]

Astragalus membranaceus is a famous traditional medicinal plant. However, drought and cadmium (Cd) pollution are the main abiotic stress factors that affect plant growth and yield and the ability to improve the host's stress resistance through the use of beneficial endophytic fungi. To evaluate the tolerance of dark septate endophytes (DSE) to various abiotic stresses, 10 DSE strains [Microsphaeropsis cytisi (Mc), Alternaria alstroemeriae (Aa), Stagonosporopsis lupini (Sl), Neocamarosporium phragmitis (Np), Paraphoma chlamydocopiosa (Pc), Macrophomina phaseolina (Mp'), Papulaspora equi (Pe), Alternaria tellustris (At), Macrophomina pseudophaseolina (Mp), and Paraphoma radicina (Pr)] were investigated under different drought and Cd stressors in vitro by using solid-plate cultures and liquid-shaker cultures in the current study. The experiments involved using varying concentrations of PEG (0, 9, 18, and 27%) and Cd2+ (0, 25, 50, and 100 mg/L) to simulate different stress conditions on DSE. Additionally, the effect of DSE (Np and At) on the growth of A. membranaceus at different field water capacities (70% and 40%) and at different CdCl2 concentrations (0, 5, 10, and 15 mg Cd/kg) in soil was studied. The results demonstrated that the colony growth rates of Aa, Np, Pc, Mp', and Mp were the first to reach the maximum diameter at a PEG concentration of 18%. Aa, Np, and At remained growth-active at 100 mg Cd/L. In addition, Aa, Np, and At were selected for drought and Cd stress tests. The results of the drought-combined-with-Cd-stress solid culture indicated that the growth rate of Np was significantly superior to that of the other strains. In the liquid culture condition, the biomasses of Np and Aa were the highest, with biomasses of 1.39 g and 1.23 g under the concentration of 18% + 25 mg Cd/L, and At had the highest biomass of 1.71 g at 18% + 50 mg Cd/L concentration, respectively. The CAT and POD activities of Np reached their peak levels at concentrations of 27% + 50 mg Cd/L and 27% + 25 mg Cd/L, respectively. Compared to the control, these levels indicated increases of 416.97% and 573.12%, respectively. Aa, Np, and At positively influenced SOD activity. The glutathione (GSH) contents of Aa, Np, and At were increased under different combined stressors of drought and Cd. The structural-equation-modeling (SEM) analysis revealed that Aa positively influenced biomass and negatively affected Cd content, while Np and At positively influenced Cd content. Under the stress of 40% field-water capacity and the synergistic stress of 40% field-water capacity and 5 mg Cd/kg soil, Np and At significantly increased root weight of A. membranaceus. This study provides guidance for the establishment of agricultural planting systems and has good development and utilization value. [ABSTRACT FROM AUTHOR]

Summary: Root‐associated fungi (RAF) and root traits regulate plant acquisition of nitrogen (N), which is limiting to growth in Arctic ecosystems. With anthropogenic warming, a new N source from thawing permafrost has the potential to change vegetation composition and increase productivity, influencing climate feedbacks. Yet, the impact of warming on tundra plant root traits, RAF, and access to permafrost N is uncertain.We investigated the relationships between RAF, species‐specific root traits, and uptake of N from the permafrost boundary by tundra plants experimentally warmed for nearly three decades at Toolik Lake, Alaska.Warming increased acquisitive root traits of nonmycorrhizal and mycorrhizal plants. RAF community composition of ericoid (ERM) but not ectomycorrhizal (ECM) shrubs was impacted by warming and correlated with root traits. RAF taxa in the dark septate endophyte, ERM, and ECM guilds strongly correlated with permafrost N uptake for ECM and ERM shrubs. Overall, a greater proportion of variation in permafrost N uptake was related to root traits than RAF.Our findings suggest that warming Arctic ecosystems will result in interactions between roots, RAF, and newly thawed permafrost that may strongly impact feedbacks to the climate system through mechanisms of carbon and N cycling. [ABSTRACT FROM AUTHOR]

Ganoderma is a fungal pathogen that can cause rot disease at the base of plant stems. This disease threatens oil palm production, especially in Southeast Asia. Trichoderma sp. fungi can control Basal Stem Rot disease in Ganoderma boninense but are ineffective. One solution that can be done to inhibit the growth of Ganoderma sp. is by using Dark Septate Endophyte (DSE) fungi. Research on DSE isolated from sugar palm (Arenga pinnata Merr.) has not been widely studied. The sugar palm plant is related to the oil palm plant in the Arecaceae family. This study aims to analyze the potential of DSE fungi from the roots of the sugar palm plant in inhibiting the pathogenic fungi Ganoderma sp. The stages of this research were isolation and purification of DSE fungi from sugar palm roots, DSE antagonists against Ganoderma sp., and DSE volatile compounds against Ganoderma sp. The results of isolation and purification showed that there were 18 DSE isolates grouped based on morphological similarities in the form of DSE fungi colony colors, where there were ten fungi isolates representing ten different colony colors, namely, isolate A.3.1 (1); A.3.2 (2); A.4.1 (2); A.4.1 (3); A.4.2; A.5.2; A.5.3; A.6.1(a); A.6.2(a); A.6.4(a). A total of 8 fungi isolates were tested for antagonists and volatile compound testing on Ganoderma sp. The results of the antagonist test showed that DSE A4.1(2) had the highest percentage of inhibition with a value of 36.12%, and isolated A6.2 had the highest percentage of inhibition and the lowest with a value of 15.65%. The testing results for volatile compounds showed that the isolate of DSE A4.2 had the highest percentage of inhibition against Ganoderma sp. at 18.25%. In comparison, the lowest inhibition percentage was obtained from DSE A5.2 fungi isolate with a value of 0.43%. [ABSTRACT FROM AUTHOR]

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Root development is critical to successful establishment after seedlings are out-planted on a forest restoration site. However, the restoration of an endangered Cinnamomum kanehirae using cuttings was limited by the lack of axial roots. Dark septate endophytes (DSEs) are an important group of asexual filamentous ascomycetous fungi and could promote the performance of host plants. In the current study, we explored the effects of four DSE strains (Melnikomyces sp., Acrocalymma vagum, Wiesneriomyces sp., and Tricholomataceae sp.) on the growth of C. kanehirae cuttings under nursery conditions. The results show that four DSE isolates are able to form symbiotic relationships with C. kanehira, enhancing the seedling height, fresh weight, and chlorophyll concentrations. Notably, the Melnikomyces sp. (DB5) showed significant improvements, secreting peroxidase and indole acetic acid. To facilitate the detection of DB5 within the host roots, we developed specific primers (DB5-1F/DB5-1R). We recommend the adoption of the endophyte inoculation approach and molecular detection methods in forestry nurseries as valuable tools to enhance silvicultural practices and contribute to the conservation of C. kanehirae. [ABSTRACT FROM AUTHOR]

Dark Septate Endophytes (DSE) and Arbuscular Mycorrhizal Fungi (AMF) are two types of endophytic fungi that have a mutually beneficial relationship with plants. This relationship is known to be influenced by various environmental factors. It has been reported that native grasses in semi-arid grasslands are extensively colonized by DSE compared to AMF, but there is limited information available for introduced grasses. Therefore, in this study, we aim to analyze the relationship between a non-native invasive grass, Megathyrsus maximus (Guinea grass), and the two endophytes, as well as the influence of soil variables on this relationship. Our analysis of root and soil samples collected from 150 locations in South Texas revealed that M. maximus is heavily colonized by both endophytes, and this relationship is influenced by soil moisture levels. Specifically, M. maximus showed a higher degree of AMF root colonization (85%) in areas with high soil moisture (20–25% soil moisture), while it had a higher degree of DSE colonization (75%) in areas with lower soil moisture conditions (0–5% soil moisture). Our results suggest that M. maximus benefits from its mutualistic relationship with fungal endophytes in semi-arid ecosystems in its introduced range, and this relationship could aid in the invasion of new habitats. [ABSTRACT FROM AUTHOR]

Aim: Dark septate endophytes (DSE) were widely used in the agriculture and ecological restoration. The objective of this work was to assess the effect of culture media nonionic surfactant and emulsifier on the biomass and metabolites of DSE strain Alternaria sp. 17463. Methods and results: Changes in the composition of DSE metabolites following the addition of Tween 80 during liquid culture of a DSE fungus were analyzed and used in growth tests of alfalfa. Shaking flask fermentation was carried out and the surfactant was fed to the fungus during the fermentation. The residual sugar content and pH declined significantly in the medium and the biomass of DSE increased by 7.27% over controls with no surfactant. Metabolomic analysis showed that adding the surfactant significantly increased the content of 63 metabolites (P < 0.05). These include lipids and lipid-like molecules, organooxygen compounds, amino acids and organic acids, and flavonoids. Enrichment analysis of metabolic pathways indicates that surfactant addition promoted carbohydrate metabolism and amino acid synthesis. A plant hydroponic experiment indicated that these changes in metabolites altered the root structure of alfalfa seedlings. They also promoted significant increases in root length and root surface area, and increased alfalfa total biomass by 50.2%. Conclusions: The addition of the surfactant promoted sugar utilization by the DSE fungus and increased the synthesis of lipids and amino acids, resulting in the ability of the fungal metabolites to change root structure and promote plant growth. [ABSTRACT FROM AUTHOR]

ABSTRACT Ectomycorrhizal (ECM) fungi and dark septate endophytes (DSEs) can both form a symbiotic relationship with the same host plant. However, the interactions that occur among these two types of fungi and their co-hosts are largely unknown. Here, we investigated interactions that occur among the ECM fungus Suillus bovinus, the DSE Phialocephala fortinii, and their co-host Pinus massoniana. We used both scanning electron microscopy and optical microscopy to characterize the morphogenesis of the two symbionts and employed the ultra-high-performance liquid chromatography–tandem mass spectrometry technique to assess the effects of fungal inoculation on the root metabolome. Under pure culture conditions, no synergistic or antagonistic effects were observed between Phi. fortinii and S. bovinus. Generally, S. bovinus and Phi. fortinii can simultaneously colonize P. massoniana roots without affecting each other’s symbiotic processes. S. bovinus can colonize the root locus where Phi. fortinii has already invaded but not vice versa, which may be due to the physical barrier effect of the mantle. Both fungi can significantly promote the growth of P. massoniana, and they have a synergistic effect on host N and K uptake. Metabolite accumulation patterns in roots inoculated with Phi. fortinii and/or S. bovinus were greatly altered, especially with respect to organic acids, flavonoids, lipids, and phenolic acids. S. bovinus inoculation significantly enhanced root flavonoid biosynthesis, whereas Phi. fortinii and dual-inoculation treatments mainly induced phenylpropanoid biosynthesis. These findings reveal compatible relationships among P. massoniana, S. bovinus, and Phi. fortinii, and suggest a theoretical basis for ECM fungi and DSE co-application when cultivating seedlings. IMPORTANCE The prevalence of both ectomycorrhizal fungi and dark septate endophytes in the roots of a wide spectrum of tree species is well recognized. In this study, we investigated the interactions that occur among the ECM fungus S. bovinus, the DSE Phi. fortinii, and their co-host, P. massoniana. The two fungi can simultaneously colonize P. massoniana roots without affecting each other’s symbiotic processes. S. bovinus appears to be superior to Phi. fortinii in microniche competition, which may be due to the physical barrier effect of the mantle. The two fungi have different effects on root metabolite accumulation patterns. S. bovinus inoculation significantly enhanced root flavonoid biosynthesis, whereas Phi. fortinii and dual-inoculation treatments mainly induced phenylpropanoid biosynthesis. This is the first study revealing the morphological and metabolic mechanisms that contribute to the compatible relationship among ECM fungi, DSEs, and their co-host.

Characterizing the diverse, root-associated fungi in mine wastes can accelerate the development of bioremediation strategies to stabilize heavy metals. Ascomycota fungi are well known for their mutualistic associations with plant roots and, separately, for roles in the accumulation of toxic compounds from the environment, such as heavy metals. We sampled soils and cultured root-associated fungi from blue grama grass (Bouteloua gracilis) collected from lands with a history of uranium (U) mining and contrasted against communities in nearby, off-mine sites. Plant root-associated fungal communities from mine sites were lower in taxonomic richness and diversity than root fungi from paired, off-mine sites. We assessed potential functional consequences of unique mine-associated soil microbial communities using plant bioassays, which revealed that plants grown in mine soils in the greenhouse had significantly lower germination, survival, and less total biomass than plants grown in off-mine soils but did not alter allocation patterns to roots versus shoots. We identified candidate culturable root-associated Ascomycota taxa for bioremediation and increased understanding of the biological impacts of heavy metals on microbial communities and plant growth. [ABSTRACT FROM AUTHOR]

Drought stress profoundly affects native desert plants' survival and performance. Among all the abiotic stresses, drought is considered a major constraint that influences the structure and functions of desert ecosystems. Arid desert ecosystems are characterized by prolonged drought, extreme temperatures, high solar radiation, water scarcity, high salinity, scarcity of soil nutrients, and poor soil structure. Such extreme desert environments are the toughest regions on earth, which present enormous challenges in conserving plant survival, growth and reproduction. Despite the predominance of these environmental conditions, native desert plant species that grow in desert environments develop complex adaptation strategies and resistance mechanisms to ameliorate the abiotic and biotic stresses in the extreme environments including changes in biochemical, physiological, and morphological levels. Arbuscular mycorrhizal fungi (AMF) form positive symbiotic associations with a considerable percentage of terrestrial plants as their host, induce distinct impacts on plant growth and protect plants from abiotic stresses. However, it is necessary to advance our understanding of the complex mechanisms associated with AMF-mediated and other dark septate endophytes (DSE)-mediated amelioration of native desert plants' drought stress resistance and associated biological adjustments such as changes in hormone balance, water and nutrient status, stomatal conductance and osmotic adjustment, antioxidant activity, and photosynthetic activity. This review provides an overview of the relationships of mycorrhiza and fungal endophytes involved in drought stress tolerance, summarizing the current knowledge and presenting possible mechanisms mediated by AMF to stimulate drought tolerance associated with native desert plants. We discuss the research required to fill the gaps and provide suggestions for future research. [ABSTRACT FROM AUTHOR]

Blueberry is a shallow root plant in which the absorption of nutrients is inefficient, resulting in slow growth under artificial cultivation conditions. Endophytes play an important role in promoting plant growth; however, the effects of Trichoderma spp. and dark septate endophytes (DSEs) on host plant growth and soil microorganisms are still debatable. We isolated two endophytic fungal species, Trichoderma koningiopsis (TK) and a DSE (Amesia nigricolor ; AN), from blueberry roots, which can solubilize insoluble phosphorus and produce amylase and cellulase to promote plant growth. We found that under dual inoculation, the colonization rate and colonization intensity of TK were higher than they were under single inoculation with TK, while the colonization rate and colonization intensity of AN were lower under dual inoculation than under single inoculation with AN. The plant nutrients, root activity, available potassium, and parts of soil phosphatase activities were highest under dual inoculation. TK inoculation resulted in the highest diversity and richness in the soil fungi and bacteria, followed by dual inoculation. The abundance of Ascomycota, Acidobacteriae, Firmicutes, and Actinobacteriota increased significantly, resulting in Trichoderma and Vicinamibacteria inoculated with TK, Chaetomium and Alicyclobacillales inoculated with AN, and Hypocreales and Burkholderiacea e with dual inoculation enriched in the soil. [ABSTRACT FROM AUTHOR]

Plant-associated microbes including dark septate endophytes (DSEs) of forest trees play diverse functional roles in host fitness including growth promotion and increased defence. However, little is known about the impact on the fungal transcriptome and metabolites during tripartite interaction involving plant host, endophyte and pathogen. To understand the transcriptional regulation of endophyte and pathogen during co-infection, Norway spruce (Picea abies) seedlings were infected with DSE Phialocephala sphaeroides , or conifer root-rot pathogen Heterobasidion parviporum , or both. Phialocephala sphaeroides showed low but stable transcripts abundance (a decrease of 40%) during interaction with Norway spruce and conifer pathogen. By contrast, H. parviporum transcripts were significantly reduced (92%) during co-infection. With RNA sequencing analysis, P. sphaeroides experienced a shift from cell growth to anti-stress and antagonistic responses, while it repressed the ability of H. parviporum to access carbohydrate nutrients by suppressing its carbohydrate/polysaccharide-degrading enzyme machinery. The pathogen on the other hand secreted cysteine peptidase to restrict free growth of P. sphaeroides. The expression of both DSE P. sphaeroides and pathogen H. parviporum genes encoding plant growth promotion products were equally detected in both dual and tripartite interaction systems. This was further supported by the presence of tryptophan-dependent indolic compound in liquid culture of P. sphaeroides. Norway spruce and Arabidopsis seedlings treated with P. sphaeroides culture filtrate exhibited auxin-like phenotypes, such as enhanced root hairs, and primary root elongation at low concentration but shortened primary root at high concentration. The results suggested that the presence of the endophyte had strong repressive or suppressive effect on H. parviporum transcripts encoding genes involved in nutrient acquisition. [ABSTRACT FROM AUTHOR]

As the only evergreen relict species in the desert environment of western China, Ammopiptanthus mongolicus (Leguminosae) roots is colonized with dark septate endophytes (DSE), but the potential of DSE to alleviate the adverse effects of drought on seedling roots remains uncertain. This study examined the effects of DSE on root growth, physiology and transcriptome of A. mongolicus under drought stress. Drought drastically reduced root biomass by 47.7%, while all DSE strains established positive symbiosis with A.mongolicus, with G.hyphopodioides having the most pronounced promoting effect. Inoculation with G. hyphopodioides alleviated drought stress injury by increasing CAT activity, AsA content and soluble sugar content in the roots, with a significant reduction in MDA accumulation by 97.7%. G. hyphopodioides also significantly increased zeatin and brassinosteroid contents, which in turn regulated the root structure and increased root activity, resulting in a 208.6% increase in root biomass. Transcriptome analysis screened 1246 differentially expressed genes (542 up-regulated and 704 down-regulated) between G. hyphopodioides inoculation under drought treatment, mainly associated with phenylpropanoid biosynthesis, ascorbic acid and aldehyde metabolism, hormone synthesis and signalling, sucrose and starch metabolism, and vitamin B6 metabolism, and further investigated and identified key potential genes and transcription factors (DREB, ERF, NAC, MYB, C2H2). These findings reveal the physiological and molecular mechanisms by which DSE symbiosis improves the drought resistance of A. mongolicus seedlings, providing valuable guidance on the use of DSE resources to promote ecological construction and production of desert plants., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

To evaluate the applicability of desert dark septate endophytes (DSEs) in crop cultivation, Alternaria alternata (Fr.) Keissl. (Aa), Paraphoma pye Moslemi & P.W.J. Taylor (Pp), and Paraphoma radicina (McAlpine) Morgan-Jones & J.F. White (Pr) were inoculated into nonhost wheat growing under three water conditions. The plants' biomass, vegetative growth, and physiological parameters were investigated. At harvest, all DSE strains were effective colonizers under all treatments. These DSEs generally positively affected wheat growth but varied among different DSE species, and this promoting effect was more obvious under drought conditions. Under mild drought (MD) treatments, Aa and Pr increased the leaf number and plant height of hosts. Pr showed a significant beneficial influence on the wheat's total biomass under all treatments, while Aa and Pp showed benefits only under the well-watered or MD treatment. The response mechanisms of DSE-inoculated wheat under stress may be due to the enhanced photosynthetic efficiency and antioxidant system. Generally, Pr had a stronger beneficial effect. The improved growth and fitness of the inoculated hosts under drought stress may reduce their water supply requirements during seedling growth. We speculate that inoculating wheat with this strain could be a promising approach for water-saving cultivation in arid environments. [ABSTRACT FROM AUTHOR]

Drought is a major abiotic stress factor affecting plant growth and production, while utilizing beneficial endophytic fungi is one of the most promising strategies for enhancing plant growth and drought tolerance. In the current study, a pot experiment was conducted to investigate the beneficial effects of dark septate endophyte (DSE) (Macrophomina pseudophaseolina, Paraphoma radicina) and Trichoderma (Trichoderma afroharzianum, Trichoderma longibrachiatum) inoculum on Astragalus mongholicus grown in sterile soil under drought stress, alone, or in combination. The addition of Trichoderma enhanced the DSE colonization in roots regardless of the water condition. Under well-watered conditions, M. pseudophaseolina inoculation significantly enhanced the biomass and root length of A. mongholicus. The two DSE and Trichoderma inoculum significantly improved calycosin-7-O-β-D-glucoside content. However, M. pseudophaseolina + T. afroharzianum inoculation better promoted root growth, whereas co-inoculation had higher active ingredient contents compared with single inoculation, except for P. radicina + T. afroharzianum. Under drought stress, DSE and Trichoderma inoculum significantly improved root biomass, root length, calycosin-7-O-β-D-glucoside content, and activities of nitrate reductase and soil urease. P. radicina + T. afroharzianum and P. radicina + T. longibrachiatum better increased root length, and all combinations of DSE and Trichoderma had a greater impact on the increase in formononetin content compared with the single treatments. Additionally, Trichoderma relies on antioxidant enzymes, growth hormones, and the redox system (ascorbic acid–glutathione) to resist drought, while DSE strains have an additional osmotic regulation system in addition to the drought resistance function possessed by Trichoderma, and the effect of co-inoculation (especially M. pseudophaseolina + T. longibrachiatum and P. radicina + T. afroharzianum) on plant physiological parameters was greater than that of single inoculation. This study provides a new research direction for the effects of DSE and Trichoderma on medicinal plant cultivated in dryland. [ABSTRACT FROM AUTHOR]

Sweet cherry is one of the most popular fresh fruits in the world. Previously, we isolated a soilborne dark septate endophyte (DSE) strain, S16, which promoted the growth of Gisela 5 sweet cherry rootstock. However, little is known about the molecular mechanism of the effect of S16 on the growth of sweet cherry. In this study, the physiological parameters and transcript profiles of sweet cherry roots were analyzed under S16 treatment compared with a control to elucidate the molecular mechanisms of the effect of this strain on sweet cherry growth. After inoculation with S16, sweet cherry seedlings exhibited more vigorous growth. Moreover, we identified 4249 differentially expressed genes (DEGs) between S16-treated plants and the control. Many of the DEGs are involved in pathways related to plant growth, such as cellular metabolic and plant hormone pathways. Additionally, some genes involved in nitrate regulation were also enriched; and these genes may be involved in the regulation of nitrate uptake in plants. Physiological index detection demonstrated that S16 could improve the nitrate assimilation of sweet cherry via NO3− transporters. This RNA-seq dataset provides comprehensive insight into the transcriptomic landscape to reveal the molecular mechanisms whereby the DSE influences the growth of sweet cherry.

Dark septate endophytes (DSEs) usually colonize plant roots, especially in stress environments. However, their relationship with plants ranges from beneficial to harmful and has remained largely uncharacterized. In the present study, 14 DSE species grouped into 11 genera were isolated from the roots of a desert plant, Artemisia ordosica, which is widely distributed in northwest China. Three dominant DSE species—Paraphoma chrysanthemicola (Pc), Alternaria chartarum (Ac), and Acrocalymma vagum (Av)—were selected and tested for their resistance to drought in vitro. Furthermore, we characterized the responses of A. ordosica under drought conditions in relation to the presence of these DSEs following inoculation. The results showed that all three strains grew well under in vitro drought stress, and the biomass of Ac and Av was significantly higher than that of the unstressed control. The effects of DSE inoculation on the growth of A. ordosica under drought stress varied according to the different DSE species but were generally beneficial. Under drought stress, Av and Pc promoted plant growth, antioxidant enzyme activity, and root development of the hosts. The Ac strain conferred obvious positive effects on the antioxidant enzyme activity of the hosts. In general, Av and Pc demonstrated better application potential for improving the drought resistance of A. ordosica. [ABSTRACT FROM AUTHOR]

Dark septate endophytes (DSE) exert a plethora of effects in regulating plant growth, signalling and stress tolerance. The advent of metagenomics has led to the identification of various species of DSE to be associated with plant organs. They are known to modulate growth, nutrient uptake, phytohormone biosynthesis and production of active bioconstituents in several plants. The interactions between the DSE and host plants are mostly mutualistic but they can also be neutral or exhibit negative interactions. The DSE has beneficial role in removal/sequestration of toxic heavy metals from various environmental sites. Here, we discuss the beneficial role of DSE in enhancing plant tolerance to heavy metal stress, drought conditions, high salinity and protection from various plant pathogens. Furthermore, the underlying mechanism of stress resilience facilitated by DSE-plant interaction has also been discussed. The article also provides insights to some important future perspectives associated with DSE-mediated phytoremediation and reclamation of polluted land worldwide thus facilitating sustainable agriculture. [ABSTRACT FROM AUTHOR]

Plants’ mineral nutrition in acidic soils can be facilitated by phosphate solubilizing fungi inhabiting the root systems of these plants. We attempt to find dark septate endophyte (DSE) isolates in the roots of wild-heather plants, which are capable of improving plants’ phosphorus nutrition levels. Bright-field and confocal laser scanning microscopy were used for the visualization of endophytes. A model system of co-cultivation with Vaccinium macrocarpon Ait. was used to study a fungal isolate’s ability to supply plants with phosphorus. Fungal phytase activity and phosphorus content in plants were estimated spectrophotometrically. In V. vitis-idaea L. roots, we obtained a Phialocephala fortinii Wang, Wilcox DSE2 isolate with acid phytase activity (maximum 6.91 ± 0.17 U on 21st day of cultivation on potato-dextrose broth medium) and the ability to accumulate polyphosphates in hyphae cells. The ability of the isolate to increase both phosphorus accumulation and biomass in V. macrocarpon is also shown. The data obtained for the same isolate, as puzzle pieces put together, indicate the possible mediation of P. fortinii DSE2 isolate in the process of phosphorus intake from inorganic soil reserves to plants.

Pine wilt disease (PWD) is a deadly disease to pines (Pinus spp.) worldwide. The occurrence of PWD can reduce the relative abundance of root ectomycorrhizal fungi (ECMF) and dark septate endophytes (DSE). However, the effects of exogenous ECMF/DSE inoculation on the rhizosphere microbial community structure of Pinus tabulaeformis infected by pine wood nematode (PWN) is little known. Here, we tested how ECMF/DSE may improve resistance to PWD by quantifying microbial carbon biomass and soil enzymatic activity among different treatments at 6 and 9 months after PWN infection. Denaturing gradient gel electrophoresis (DGGE) was used to study the microbial community structure at 3, 6, and 9 months after PWN infection in the rhizosphere of P. tabulaeformis seedlings inoculated with ECMF/DSE. The results showed that exogenous ECMF/DSE inoculation reduced the disease severity caused by PWN infection. After PWN infection, the rhizosphere microbial carbon of seedlings inoculated with Amanita vaginata, Suillus bovinus, Gaeumannomyces cylindrosporus, and Paraphoma chrysanthemicola was 38.16, 49.67, 42.11, and 96.05% higher than that of the control group, respectively. Inoculation of ECMF/DSE inhibited the decrease of rhizosphere microbial biomass caused by PWN infection. The richness and diversity of P. tabulaeformis rhizosphere fungi at 9 months were reduced by PWN infection but partially recovered by the exogenous fungi (ECMF/DSE) inoculation except for P. chrysanthemicola, which indicates a role of ECMF/DSE in maintaining stability of the microbial community. Inoculation with ECMF/DSE increased the beneficial bacterial (Thauera sp., Mesorhizobium sp., etc.) and fungal groups (Tomentella ellisii, Wilcoxina mikolae, etc.) of in the rhizosphere. In summary, exogenous ECMF/DSE inoculation could increase P. tabulaeformis resistance to PWD probably by improving the rhizosphere microenvironment.

Copyright of Mycosystema is the property of Mycosystema Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Mycosystema is the property of Mycosystema Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Pine wilt disease (PWD) is a deadly disease to pines (Pinus spp.) worldwide. The occurrence of PWD can reduce the relative abundance of root ectomycorrhizal fungi (ECMF) and dark septate endophytes (DSE). However, the effects of exogenous ECMF/DSE inoculation on the rhizosphere microbial community structure of Pinus tabulaeformis infected by pine wood nematode (PWN) is little known. Here, we tested how ECMF/DSE may improve resistance to PWD by quantifying microbial carbon biomass and soil enzymatic activity among different treatments at 6 and 9 months after PWN infection. Denaturing gradient gel electrophoresis (DGGE) was used to study the microbial community structure at 3, 6, and 9 months after PWN infection in the rhizosphere of P. tabulaeformis seedlings inoculated with ECMF/DSE. The results showed that exogenous ECMF/DSE inoculation reduced the disease severity caused by PWN infection. After PWN infection, the rhizosphere microbial carbon of seedlings inoculated with Amanita vaginata , Suillus bovinus , Gaeumannomyces cylindrosporus , and Paraphoma chrysanthemicola was 38.16, 49.67, 42.11, and 96.05% higher than that of the control group, respectively. Inoculation of ECMF/DSE inhibited the decrease of rhizosphere microbial biomass caused by PWN infection. The richness and diversity of P. tabulaeformis rhizosphere fungi at 9 months were reduced by PWN infection but partially recovered by the exogenous fungi (ECMF/DSE) inoculation except for P. chrysanthemicola , which indicates a role of ECMF/DSE in maintaining stability of the microbial community. Inoculation with ECMF/DSE increased the beneficial bacterial (Thauera sp., Mesorhizobium sp., etc.) and fungal groups (Tomentella ellisii , Wilcoxina mikolae , etc.) of in the rhizosphere. In summary, exogenous ECMF/DSE inoculation could increase P. tabulaeformis resistance to PWD probably by improving the rhizosphere microenvironment. [ABSTRACT FROM AUTHOR]

High-elevation ecosystems are expected to be particularly sensitive to climate warming because cold temperatures constrain biological processes. Deeper understanding of the consequences of climate change will come from studies that consider not only the direct effects of temperature on individual species, but also the indirect effects of altered species interactions. Here we show that 20 years of experimental warming has changed the species composition of graminoid (grass and sedge) assemblages in a subalpine meadow of the Rocky Mountains, USA, by increasing the frequency of sedges and reducing the frequency of grasses. Because sedges typically have weak interactions with mycorrhizal fungi relative to grasses, lowered abundances of arbuscular mycorrhizal (AM) fungi or other root-inhabiting fungi could underlie warming-induced shifts in plant species composition. However, warming increased root colonization by AM fungi for two grass species, possibly because AM fungi can enhance plant water uptake when soils are dried by experimental warming. Warming had no effect on AM fungal colonization of three other graminoids. Increased AM fungal colonization of the dominant shrub Artemisia tridentata provided further grounds for rejecting the hypothesis that reduced AM fungi caused the shift from grasses to sedges. Non-AM fungi (including dark septate endophytes) also showed general increases with warming. Our results demonstrate that lumping grasses and sedges when characterizing plant community responses can mask significant shifts in the responses of primary producers, and their symbiotic fungi, to climate change.

Soil contamination by metals is of particular interest, given that their retention times within the profile can be indefinite. Thus, phytostabilization can be viewed as a means of limiting metal toxicity in soils. Due to their ability to grow on contaminated soils, alders have repeatedly been used as key species in phytostabilization efforts. Alder ability to grow on contaminated sites stems, in part, from its association with microbial endophytes. This work emphasizes the fungal endophytes populations associated with Alnus incana ssp. rugosa and Alnus alnobetula ssp. crispa (previously A. viridis ssp. crispa) under a phytostabilization angle. Fungal endophytes were isolated from alder trees that were growing on or near disturbed environments; their tolerances to Cu, Ni, Zn, and As, and acidic pH (4.3, 3, and 2) were subsequently assessed. Cryptosporiopsis spp. and Rhizoscyphus spp. were identified as fungal endophytes of Alnus for the first time. When used as inoculants for alder, some isolates promoted plant growth, while others apparently presented antagonistic relationships with the host plant. This study reports the first step in finding the right fungal endophytic partners for two species of alder used in phytostabilization of metal-contaminated mining sites.

To evaluate the applicability of desert dark septate endophytes (DSEs) in crop cultivation, Alternaria alternata (Fr.) Keissl. (Aa), Paraphoma pye Moslemi & P.W.J. Taylor (Pp), and Paraphoma radicina (McAlpine) Morgan-Jones & J.F. White (Pr) were inoculated into nonhost wheat growing under three water conditions. The plants’ biomass, vegetative growth, and physiological parameters were investigated. At harvest, all DSE strains were effective colonizers under all treatments. These DSEs generally positively affected wheat growth but varied among different DSE species, and this promoting effect was more obvious under drought conditions. Under mild drought (MD) treatments, Aa and Pr increased the leaf number and plant height of hosts. Pr showed a significant beneficial influence on the wheat’s total biomass under all treatments, while Aa and Pp showed benefits only under the well-watered or MD treatment. The response mechanisms of DSE-inoculated wheat under stress may be due to the enhanced photosynthetic efficiency and antioxidant system. Generally, Pr had a stronger beneficial effect. The improved growth and fitness of the inoculated hosts under drought stress may reduce their water supply requirements during seedling growth. We speculate that inoculating wheat with this strain could be a promising approach for water-saving cultivation in arid environments.

Dryland communities may mitigate the loss of limited resources by exchanging nutrients through subterranean fungal connections, termed fungal loops. In arid grasslands, fungal loops can influence community composition and primary productivity, yet their ecological significance across dryland systems remains unexplored. We investigated the functional role of fungal loops in nutrient translocation in a North American shrubland ecosystem.We traced the movement of 15N from moss‐dominated biocrusts to the dominant xeric shrub Larrea tridentata, and the movement of 13C from L. tridentata to biocrusts in plots established in situ in the Sonoran Desert. Measurements occurred at three time points spanning 1 week following a simulated 2.5 mm rainfall event, and at distances up to 1 m from tracer application. We also used ITS sequencing to investigate changes in fungal community composition in soils over the 1‐week period.We discovered movement of 15N from biocrusts into L. tridentata foliage as well as 15N movement to other spatially isolated moss‐dominated biocrust patches, yet this movement did not occur until 4–6 days post‐rainfall, when significantly higher δ15N was observed in L. tridentata and biocrusts compared to previous days. We did not observe consistent patterns of 13C movement from L. tridentata into neighbouring shrubs or biocrusts, suggesting differential environmental drivers for carbon movement in this system. Fungal communities exhibited a decrease in alpha diversity on the last day of the study, indicative of a delayed community response to rainfall concomitant with nutrient translocation. Fungal endophyte orders Pleosporales and Pezizales dominated all plot soils, and order Pleosporales was significantly more abundant in 15N enriched plots, suggesting that dark septate endophytic fungi were involved in nitrogen translocation. The delay in nutrient translocation may reflect a rainfall‐triggered rebuilding of mycelial networks between community members following drought.Synthesis. Our results point to fungal‐mediated nutrient exchange pathways in a previously uninvestigated vegetation type, shrublands, where nutrients are translocated between moss‐dominated biocrusts and nearby shrubs. We provide the first evidence that nutrient transfer may be delayed up to 6 days following rainfall, consistent with pulse‐dynamic responses in drylands, and that moss‐dominated biocrusts play a role in fungal loops. [ABSTRACT FROM AUTHOR]

In nature conditions, mutualization of ericaceous plant (Ericaceae) roots with mycorrhizal fungi or other soil symbiotic fungi improves efficiency on nutrient uptake and tolerance to heavy metal stress. Effects of ericoid mycorrhizal fungi (EMF) or dark septate endophyte (DSE) colonization have been evaluated in highbush blueberry (Vaccinium corymbosum) but remained unclear in rabbiteye blueberry (V. virgatum Ait.). In this study, callused cuttings of 'NTU-104' rabbiteye blueberry were grown in substrate containing either sterilized (SP) or unsterilized (UP) nature Finnish peat moss as a fungal inoculum. Vegetative growth, fungal colonization frequency (Cf) and intensity (Ci), substrate pH and electrical conductivity (EC), and plant nutritional elements were assessed. Sterilization did not completely exclude fungi resources in the peat moss and colonization of EMF and DSE was found in both SP and UP substrate types. Regardless, UP treatment resulted in greater total Cf (69.3%) and Ci (9.91%) than those of SP (41.49% and 6.17%, respectively). In either substrate type, both Cf and Ci of DSE were greater than those of EMF. Plants in UP treatment produced more shoots (2.33), number of leaves (76.33), greater total leaf area (494.18 cm2), and shoot length (121.78 cm) than in SP substrate (1.67, 24.17, 116.13 cm2, and 30.22 cm, respectively). Fresh weights of roots, shoots, and leaves in UP plants were significantly greater (7.57, 9.64, and 15.25 g, respectively) than in SP plants (1.29, 2.62, and 3.08 g, respectively). Dry weights of roots, shoots, and leaves in UP plants were also significantly greater (4.34, 2.37, and 4.51 g, respectively) than in SP plants (0.67, 0.47, and 0.90 g, respectively). Concentrations of phosphorous and magnesium in roots and potassium in shoots were increased in UP plants while other nutritional elements remained consistent. Contents of all nutritional elements were increased in UP plants due to greater dry weight. After the establishment of the transplants, pH and EC of both substrate types were in the optimal range for blueberries but significant lower pH while higher EC were measured in UP substrate. The results indicated that using nature Finnish peat moss as a symbiotic fungi inoculum was capable of establishing symbiotic fungal colonization and promoting rooting and vegetative growth in rabbiteye blueberry cuttings. [ABSTRACT FROM AUTHOR]

This study determined the influence of soil nitrogen and phosphorus on the colonisation dynamics of arbuscular mycorrhizal fungi (AMF) and Dark Septate Endophytes (DSE) in plant species adapted to nutrient poor soils. Plant colonisation dynamics were investigated using a field experiment and a manipulative greenhouse experiment on Australian native seedlings. Tubestock of Poa labillardierei were transplanted into the field to large tracts of land of high and low nutrient availability, near Sydney, Australia, and root colonisation was determined from monthly plant collections over three months, between late austral autumn and through winter. In the greenhouse experiment, two native shrubs and one grass, respectively, Rhagodia candolleana, Dodonaea triquetra and P. labillardierei, were germinated from seeds and grown under a full factorial nitrogen and phosphorus fertilisation experiment for three months before root colonisation was determined. The selected study species were of varied mycotrophy. AMF colonisation in both experiments was lowest in plants from high nutrient treatments. Removal of either nitrogen or phosphorus from the fertiliser resulted in the same patterns of colonisation, with AMF being greater when either nutrient was removed. DSE colonisation was greatest in high nutrient soils. However, colonisation did not vary with nutrient treatments in the glasshouse experiment, suggesting that nitrogen and phosphorus minimally affect DSE colonisation. The difference in AMF and DSE colonisation patterns demonstrates a distinction in how different fungal symbionts are affected by abiotic factors. Both nitrogen and phosphorus are important drivers of colonisation dynamics of AMF. The results indicate the potential for disparate controls of AMF and DSE root associations. [ABSTRACT FROM AUTHOR]

We investigated the effects of ericoid mycorrhizal fungi (ERMFs) or dark septate endophytic fungi (DSEFs) on secondary metabolite production and growth promotion of Rhododendron pseudochrysanthum. The strains Rf9 (Cryptosporiopsis sp.) and Rf32 (Cryptosporiopsis sp.) were isolated from Rhododendron formosanum, whereas strains Rp7 (Phialocephala fortinii), Rp9 (Hyaloscyphaceae sp.), and Rp28 (Phialocephala fortinii) were isolated from R. pseudochrysanthum (R. morii). We studied their molecular relationships using phylogenetic analysis and divided these five strains into three groups (Cryptosporiopsis sp., Phialocephala fortinii, and Hyaloscyphaceae sp.). We found that strains Rf9 and Rf32 belonged to ERMFs, which form a hyphal complex with R. pseudochrysanthum, whereas strains Rp7, Rp9, and Rp28 belonged to DSEFs, which form microsclerotia on R. pseudochrysanthum. The endophytic fungi can promote the growth of R. pseudochrysanthum seedlings, and the total fresh weight of inoculated seedlings was higher than that of the control seedlings. In addition, the phytochemical profile showed that the methanolic extract of Rp7-inoculated seedlings had the highest content of rutin, hyperoside, quercitrin, and (2R,3S)-catechin among all inoculated seedlings. In conclusion, DSEFs and ERMFs promoted the growth response and secondary metabolite production of R. pseudochrysanthum seedlings. [ABSTRACT FROM AUTHOR]

PREMISE: Root‐associated fungi provide a wide range of functions for their host plants, including nutrient provisioning, pathogen protection, and stress alleviation. In so doing, they can markedly influence host‐plant structural and physiological traits, although the degree to which these effects vary within particular plant host species is not well understood. METHODS: We conducted a 7‐month common‐garden inoculation experiment to test the potential effects of a marine fungus (Lulwoana sp.) on the phenotypic traits of different genotypes of the host, the salt marsh plant species Spartina alterniflora. Lulwoana belongs to the dark septate endophytes (DSE), a polyphyletic group of fungi that are commonly found colonizing healthy plant roots, though their ecological role remains unclear. RESULTS: We documented significant impacts of Lulwoana on S. alterniflora morphology, biomass, and biomass allocation. For most traits in our study, these impacts varied significantly in direction and/or magnitude across S. alterniflora genotypes. Effects that were consistent across genotype were generally negative. Plant response was not predicted by the percentage of roots colonized, consistent with findings that dark septate endophytes do not necessarily influence plant growth responses through direct contact with roots. CONCLUSIONS: The observed changes in stem height, biomass, and biomass allocation have important effects on plant competitive ability, growth, and fitness, suggesting that plant–fungal interactions have community and ecosystem level effects in salt marshes. [ABSTRACT FROM AUTHOR]

Background and aims: Dark septate endophytes (DSE) are a group of multifunctional fungi that ubiquitously colonize the roots of numerous plants worldwide, benefiting the nutrition and adaptation of hosts to various stressed environments. How DSE benefit phosphorus absorption by their host plants remains unclear. Methods: We established pot cultures and compartmentalized microcosms in the greenhouse and used transcriptomic analysis to examine the response of maize to inoculation with a DSE strain, Exophiala pisciphila H93, which has been found to be capable of promoting plant growth and enhancing the tolerance of maize to heavy metals. Results: H93 promoted the biomass, phosphorus absorption and photosynthesis of inoculated maize by enhancing phosphorus enzyme activities in the rhizosphere and by decreasing the pH of the rhizosphere compared with non-inoculated controls, either in sufficient or deficient phosphorus conditions in pot cultures. H93 inoculation changed the transcriptional pattern of maize related to 8 metabolic pathways. While H93 did not induce particular phosphate transporter gene expression under deficient phosphorus conditions, it dissolved the sparingly soluble phosphates (tricalcium phosphate) in the rhizosphere. Conclusions: Enhanced phosphorus absorption by the host plant by DSE (H93) seemed to occur independently of DSE-induced genes involved in phosphorus absorption. The greatest contribution of DSE to phosphorus utilization of hosts might be their efficiency in transferring sparingly soluble phosphorus into soluble phosphate (Pi). [ABSTRACT FROM AUTHOR]

Copyright of Journal of Southern Agriculture is the property of Journal of Southern Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This is the first study to discuss the effects of dark septate endophytes (DSE) on the growth promotion and berberine concentration in Mahonia oiwakensis, whose extract (MOE) has been suggested to have potential therapeutic effects against human lung cancer. First, as per phylogenetic analysis, the strains were divided into four groups: CkDB2, CkDB5, MoAL2 and MoAL5. All of these were DSEs, which could form microsclerotia in M. oiwakensis. The growth response experiment revealed that inoculation of the plant with MoAL5 and CkDB5 promoted an increase in the total fresh weight of the seedlings. Chemical composition analysis showed that seedlings inoculated with CkDB5 had the highest berberine concentration. These results showed that some DSEs have the ability to promote growth and induce phytochemical responses in the host plant.

Exophiala pisciphila is one of the dominant dark septate endophytes (DSEs) colonizing metal-polluted slag heaps in southwest China. It shows numerous super-metal-tolerant characteristics, but the molecular mechanisms involved remain largely unknown. In the present study, the functional roles of a specific set of ATP-binding cassette (ABC) transporters in E. pisciphila were characterized. In total, 26 EpABC genes belonging to 6 subfamilies (ABCA to ABCG) were annotated in previous transcriptome sequencing libraries, and all were regulated by metal ions (Pb, Zn, and Cd), which was dependent on the metal species and/or concentrations tested. The results from the heterologous expression of 3 representative EpABC genes confirmed that the expression of EpABC2.1, EpABC3.1, or EpABC4.1 restored the growth of metal-sensitive mutant Saccharomyces cerevisiae strains and significantly improved the tolerance of Arabidopsis thaliana to Pb, Zn, and Cd. Interestingly, the expression of the 3 EpABC genes further altered metal (Pb, Zn, and Cd) uptake and accumulation and promoted growth by alleviating the inhibitory activity in yeast and thale cress caused by toxic ions. These functions along with their vacuolar location suggest that the 3 EpABC transporters may enhance the detoxification of vacuolar compartmentation via transport activities across their membranes. In conclusion, the 26 annotated EpABC transporters may play a major role in maintaining the homeostasis of various metal ions in different cellular compartments, conferring an extreme adaptative advantage to E. pisciphila in metal-polluted slag heaps. IMPORTANCE Many ABC transporters and their functions have been identified in animals and plants. However, little is known about ABC genes in filamentous fungi, especially DSEs, which tend to dominantly colonize the roots of plants growing in stressed environments. Our results deepen the understanding of the function of the ABC genes of a super-metal-tolerant DSE (E. pisciphila) in enhancing its heavy metal resistance and detoxification. Furthermore, the genetic resources of DSEs, e.g., numerous EpABC genes, especially from super-metal-tolerant strains in heavy metal-polluted environments, can be directly used for transgenic applications to improve tolerance and phytoextraction potential. [ABSTRACT FROM AUTHOR]

Soil contamination by metals is of particular interest, given that their retention times within the profile can be indefinite. Thus, phytostabilization can be viewed as a means of limiting metal toxicity in soils. Due to their ability to grow on contaminated soils, alders have repeatedly been used as key species in phytostabilization efforts. Alder ability to grow on contaminated sites stems, in part, from its association with microbial endophytes. This work emphasizes the fungal endophytes populations associated with Alnus incana ssp. rugosa and Alnus alnobetula ssp. crispa (previously A. viridis ssp. crispa) under a phytostabilization angle. Fungal endophytes were isolated from alder trees that were growing on or near disturbed environments; their tolerances to Cu, Ni, Zn, and As, and acidic pH (4.3, 3, and 2) were subsequently assessed. Cryptosporiopsis spp. and Rhizoscyphus spp. were identified as fungal endophytes of Alnus for the first time. When used as inoculants for alder, some isolates promoted plant growth, while others apparently presented antagonistic relationships with the host plant. This study reports the first step in finding the right fungal endophytic partners for two species of alder used in phytostabilization of metal-contaminated mining sites. [ABSTRACT FROM AUTHOR]

Seed endophytes, as primary symbionts, may influence formation of secondary symbioses in maturing hosts. We hypothesize that such priority effects are a function of the presence and the identity of the primary symbiont, and are simulated via inoculation with primary symbionts. We sampled primary symbionts in winter wheat using culture-based techniques and next generation sequencing. Ninety-one percent of 6300 seeds had either one or no isolates. NGS data supported this with over 99% fewer reads detected in seeds having no isolates. Alternaria and Cladosporium spp., accounted for almost 80% of the primary symbionts isolated from seeds but only 36% of OTUs. Bacteria accounted for 13% of isolates but 27% of OTUs. We grew seedlings with or without primary symbiont isolates aseptically in vitro with roots in contact with a suspension of the rhizosphere symbiont Phialocephala fortinii. Seedlings having Cladosporium spp. or bacteria as primary symbionts increased the P. fortinii root colonization in 3 weeks by 30% and 50%, respectively, compared to seedlings lacking symbionts. Alternaria primary symbionts had no effect on root colonization by P. fortinii. However, Cladosporium and Alternaria inocula reduced P. fortinii colonization by 75% and 42%, respectively, at 3 weeks, so natural priority effects were not simulated by inoculation with fungi. Bacillus inoculum doubled P. fortinii colonization, but colonization was delayed. Primary symbionts of wheat seed can have strong, natural priority effects dependent on their presence and identity, but inoculation does not always simulate natural effects. [ABSTRACT FROM AUTHOR]