Dark Septate Endophytes Research Articles

The dark septate endophyte Phialocephala sphaeroides suppresses conifer pathogen transcripts and promotes root growth of Norway spruce.

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.

Endorhizal fungal symbiosis in lycophytes and metal(loid)-accumulating ferns growing naturally in mine wastes in Mexico

Ferns and lycophytes are pioneer plants that can be useful for revegetation. Their natural distribution and interaction with soil fungal endophytes can increase plant fitness but have received little attention. This study aimed to identify these plant species in mine wastes, and determine colonization by arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE). The pseudo-total and diethylenetriamine pentaacetic acid (DTPA)-extractable rhizosphere concentrations of As, Cu, Cd, Pb, and Zn, bioavailability index (BI), and bioconcentration factor (BCF) were analyzed. Six ferns and one lycophyte were identified. Arsenic and metal concentrations were high, which were plant and site-dependent. All species showed hyperaccumulation of As in fronds, especially Argyrochosma formosa (2,883) and Notholaena affinis (2,160) had the highest concentrations (mg kg−1). All plants were colonized by AMF (3%−24%) and DSE (2%−33%). Astrolepis sinuata and Myriopteris notholaenoides had the maximum colonization by AMF and A. formosa by DSE. This study identifies for the first time five ferns and one lycophyte species on mine wastes, their As hyperaccumulation capacity and the simultaneous fungal colonization by AMF and DSE. These are relevant plant traits for phytoremediation. However, fungal identification and the role colonization by AMF and DSE requires full analysis.

Improved Tolerance of Artemisia ordosica to Drought Stress via Dark Septate Endophyte (DSE) Symbiosis.

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.

Effects of a Dark Septate Fungal Endophyte on the Growth and Physiological Response of Seedlings to Drought in an Epiphytic Orchid.

Dark septate endophytes (DSE) are a group of facultative biotrophic root-colonizing fungi that live within a plant for a part of their life cycle without causing any apparent, overt negative effects. These fungi have been found in >600 different plant species, including orchids. Although the precise ecological functions of dark septate fungal endophytes are not yet well understood, there is increasing evidence that they enhance host growth and nutrient acquisition, and improve the plant’s ability to tolerate biotic and abiotic stresses. In this research, we tested the effects of a DSE isolated from the roots of the epiphytic orchid Coelogyne viscosa on the growth and drought tolerance of orchid seedlings. Our results showed that addition of DSE inoculum significantly enhanced biomass of seedlings and increased the activities of drought resistance related enzymes and the accumulation of osmoregulatory substances. These results suggest that DSE can fulfill important ecological functions in stressful environments and potentially play an important role in the life cycle of epiphytic orchids.

Metabarcoding of fungal assemblages in Vaccinium myrtillus endosphere suggests colonization of above-ground organs by some ericoid mycorrhizal and DSE fungi

Plants harbor in their external surfaces and internal tissues a highly diverse and finely structured microbial assembly, the microbiota. Each plant compartment usually represents a unique ecological niche hosting a distinct microbial community and niche differentiation, which may mirror distinct functions of a specialized microbiota, has been mainly investigated for bacteria. Far less is known for the fungal components of the plant-associated microbiota. Here, we applied a metabarcoding approach to describe the fungal assemblages in different organs of Vaccinium myrtillus plants (Ericaceae) collected in a subalpine meadow in North-West Italy, and identified specific taxa enriched in internal tissues of roots, stems, leaves and flowers. We also traced the distribution of some important fungi commonly associated with plants of the family Ericaceae, namely the ericoid mycorrhizal (ErM) fungi and the dark septate endophytes (DSE), both playing important roles in plant growth and health. Operational taxonomic units attributed to established ErM fungal species in the genus Hyaloscypha and to DSE species in the Phialocephala-Acephala applanata complex (PAC) were found in all the plant organs. Mycorrhizal fungi are thought to be strictly associated with the plant roots, and this first observation of ErM fungi in the above-ground organs of the host plant may be explained by the evolutionary closeness of ErM fungi in the genus Hyaloscypha with non mycorrhizal fungal endophytes. This is also witnessed by the closer similarities of the ErM fungal genomes with the genomes of plant endophytes than with those of other mycorrhizal fungi, such as arbuscular or ectomycorrhizal fungi.

Effects of Dark Septate Endophytes on the Performance and Soil Microbia of Lycium ruthenicum Under Drought Stress.

In the current study, we explored the effects of dark septate endophytes (DSE) (Neocamarosporium phragmitis, Alternaria chlamydospore, and Microascus alveolaris) on the performance and rhizosphere soil microbial composition of Lycium ruthenicum Murr under drought stress. Differences in plant growth and physiological indexes, soil parameters, and microbial composition under different treatments were studied. Three DSE species could form good symbiotic relationships with L. ruthenicum plants, and the symbionts depended on DSE species and water availability. Inoculation of DSE had the greatest benefit on host plants under drought conditions. In particular, N. phragmitis and A. chlamydospore had a significant positive influence on the biomass, morphological and physiological indexes of host plants. Additionally, the content of arbuscular mycorrhiza (AM) fungi, gram-negative bacteria, and actinomycetes in the soil was significantly elevated after DSE inoculation in the absence of water. Based on a variance decomposition analysis, DSE was the most important factor affecting the growth and physiological parameters of host plants, and DSE inoculation combined with water conditions significantly affected the contents of soil microbial communities. Structural equation model (SEM) analysis showed that the positive effects of DSE on L. ruthenicum varied with DSE species and plant parameters under different water conditions. These results are helpful to understand the ecological function of DSE and its potential application in the cultivation of L. ruthenicum plants in drylands.

Epichloë endophyte affects the root colonization pattern of belowground symbionts in a wild grass

Plants host multiple symbionts that interact with each other affecting plant performance and regulating their establishment. Here, we analyzed how the association with Epichloë endophytes affects belowground colonization by Dark Septate Endophytes (DSE) and arbuscular mycorrhizal fungi (AMF) in the grass Bromus auleticus . Epichloë -symbiotic (E+) and Epichloë -non symbiotic (E−) plants were sampled from a long-term experimental plot and colonization structures were analyzed in the roots. We also examined the influence of Epichloë exudates on the in vitro growth of DSE Microdochium bolleyi isolated from roots. Epichloë symbiosis increased AMF colonization, although differences were not significant. Despite the lack of differences in total DSE colonization, in concordance with in vitro findings, a higher significant abundance of microsclerotia was observed in E+ plants. A negative correlation between total mycorrhizal and DSE was found. Our findings show a more uniform root colonization pattern in E+ plants, suggesting a root symbiosis modulating role. • DSE microsclerotia was significantly more abundant in B . auleticus E+ plants than E−. • Arbuscules abundance was double in plants associated with Epichloë compared to E−. • Epichloë endophytes exudates did not affect DSE strain growth in vitro . • DSE negatively correlate with AMF colonization. • E+ plants presents a more uniform root colonization pattern than Eplichloë -free.

The Dark Septate Endophyte, Phialocephala fortinii J2PC4, Mitigates Southern Rice Black-Streaked Dwarf Disease and Impacts the Mortality of White Back Planthopper

Southern rice black-streaked dwarf disease (SRBSDD), caused by the southern rice black-streaked dwarf virus (SRBSDV) and transmitted by the white-backed planthopper (WBPH), is a severe disease responsible for significant yield losses in Southeast Asia, including China. The present study investigated utilization of dark septate endophyte (DSE) fungi against SRBSDD and WBPHas a new, effective approach for managing this disease. An isolate of the DSE fungus, Phialocephala fortinii J2PC4, was selected based on its effective symbiosis with rice. Phialocephala fortinii J2PC4 significantly promoted the growth of the rice, increasing plant height (14.8%), fresh weight (59.5%), and dry weight (60.5%) relative to the untreated control in growth-promotion experiments. In experiments assessing disease and pest suppression, growth of rice plants P. fortinii J2PC4 also promoted growth, increasing plant height(22.4%), fresh weight (74.0%), and dry mass (32.4%). Plants infested with WBPH for 48 hours exhibited a WBPH mortality rate of 8.2% in P. fortinii J2PC4 treated plants compared to 1.5% in the control plants. Disease incidence of SRBSDD in the plants treated with P. fortinii J2PC4 exhibited a 28.5% reduction in SRBSDD disease incidence compared to control plants. P. fortinii J2PC4 colonization of rice seedlings decreased the malondialdehyde (MDA) content, increased the superoxide dismutase (SOD) and peroxidase (POD) activity in rice leaves and induced the expression of the resistance-related genes, AOS, PR1a, and PR1b. In contrast POX1 and OsSAUR2 were down-regulated, relative to control plants. Larval production by WBPH in P. fortinii J2PC4 treated plants was also 24.7% lower than control plants in the pest resistance experiment. Our results provide new insights on use of the DSE fungus, P. fortinii J2PC4, as a biofertilizer and a biocontrol agent, which can potentially be applied as a new, safe and effective treatments for growth stimulation and disease and pest control in rice plants.

Thermal Infrared Evaluation of the Influence of Arbuscular Mycorrhizal Fungus and Dark Septate Endophytic Fungus on Maize Growth and Physiology

Thermal infrared imaging technology was used to understand the effects of arbuscular mycorrhizal fungi (AMF) and dark septate endophytic (DSE) fungi, both separately and together, on plant growth and physiological status, and to screen and develop efficient microbial agents in a pot experiment design. Eight treatments comprised the control (CK), AMF inoculation alone, DSE fungal treatments (DSE20%, DSE40% and DSE80%; 2, 4, 8 × 105 CFU mL−1) and combined inoculation treatments (DSE20% + AMF, DSE40% + AMF, and DSE80% + AMF). Canopy temperature (Tcanopy) and stomatal conductance (gs) were monitored at different growth stages, and plant biomass-related indicators were obtained at harvest. These indicators were used to assess plant growth and the physiological status resulting from the different inoculation treatments. During plant growth, the plant Tcanopy decreased following inoculation. Differences in Tcanopy between control and inoculated plants were detected by thermal infrared imaging technology and were −3.8 to + 9.3 °C (control–inoculation treatment). Growth index and Tcanopy monitoring indicate that the growth-promoting effect of combined inoculation was higher than that of either fungal type alone, with DSE80% + AMF producing the highest growth promotion. During the growth process of inoculated maize, the effect of inoculated AMF on the physiological condition of maize growth can be better monitored by thermal infrared at 10 a.m., 12 p.m., 2 p.m. and 4 p.m. on the 31st–57th days of the growth period. The method and results of this experiment are conducive to the rapid and efficient monitoring of the effects of microorganisms on plant growth and physiological status and can be applied to the screening, application, and promotion of microbial agents.

Root‐associated fungi not tree density influences stand nitrogen dynamics at the larch forest–tundra ecotone

Abstract Greater tree density and forest productivity at the tundra–taiga ecotone (TTE) are expected with climate warming, with potential feedbacks to the climate system. Yet, competition for nitrogen (N) may impact TTE dynamics. Greater tree density will likely increase N demand, while reducing N supply through soil shading and slower decomposition rates. We explored whether characteristics of roots and root‐associated fungi important to N acquisition responded to changes in density at the TTE and were related to above‐ground stand productivity and N cycling. We measured rooting depth, uptake of N forms among soil layers and ectomycorrhizal (EcM) colonization and composition along a natural tree density gradient of monodominant larch Larix cajanderi in northeastern Siberia. We tested relationships between larch root and fungal characteristics, above‐ground productivity and stand‐level N cycling parameters. Overall, there was preferential uptake of ammonium compared to glycine or nitrate. Nitrogen uptake was greatest in shallow soils of the organic horizon and related to root chemistry, root‐associated fungi and above‐ground N cycling parameters, but the direction of these relationships depended on N form. Uptake of different N forms, rooting depth and EcM colonization and composition were not related to tree density, but fungal composition was correlated with root N chemistry and above‐ground N cycling parameters. In addition to EcM, the abundance of dark septate endophytes and other ascomycetous taxa was positively related to N uptake and above‐ground N cycling parameters. Synthesis. There was little impact of tree density on root and fungal parameters related to N acquisition suggesting intraspecific larch competition for N was not amplified with increased density. There was, however, a strong impact of root‐associated fungi on N uptake and stand N dynamics regardless of tree density. Together, this suggests an important role of root‐associated fungi on broadscale patterns of N cycling in TTE larch forests independent of changes in tree density expected with climate warming.

Ontogenetic changes in root traits and root‐associated fungal community composition in a heteroblastic epiphytic bromeliad

Heteroblastic variations among leaf traits is a well‐known process, especially in bromeliad species that show abrupt changes, but little effort was directed to test whether comparable ontogenetic variation occurs among root traits and their fungal partners. Usually considered for their mechanical role, roots of bromeliads may also play a role in resource use that we expect to differ between ontogenetic stages, namely nutrient pulse‐supplied atmospherics (young stage) and continuously‐supplied tanks (later stage). On a selection of adventitious roots of the heteroblastic epiphyte Lutheria splendens, we explored 1) ontogenetic variations in morphological and anatomical root traits, namely the number of adventitious roots and tips, total root length, average root diameter, root tissue density, specific root length and root tissue areas, and 2) ontogenetic changes in the composition of the root‐associated fungal communities using ITS1 region‐based high‐throughput sequencing. Plant size, taken as an indicator of gradual ontogenetic variations, and plant stage had significant effects on root traits, unless for root tissue density. The number of adventitious roots and tips, the total root length, average root diameter and all root tissue areas (i.e. velamen, outer cortex, inner cortex, vascular cylinder) increased gradually with ontogeny while the specific root length decreased abruptly. The root‐associated fungal communities varied with plant stage. The tank stage showed higher proportion of mycorrhizal fungi and a lower abundance of dark septate endophyte as compared to atmospheric stage. Overall, we demonstrated significant ontogenetic variations of root traits and fungal partners in bromeliad species that suggest important changes in the strategy for resource use as plants mature. We invite future root trait studies to better account for ontogenetic variations.

Insights into the beneficial roles of dark septate endophytes in plants under challenging environment: resilience to biotic and abiotic stresses.

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.

Relationship of root dark septate endophytes and soil factors to plant species and seasonal variation in extremely arid desert in Northwest China

Investigations on host affiliations, seasonal variation and physiological response to drought tolerance of dark septate endophytes (DSE) in extremely arid desert environments can help explain the adaptive mechanisms of these endophytes in desert ecosystems. The colonization and species diversity of DSE and the soil factors in the rhizospheres of five desert shrubs were therefore determined in Anxi extremely arid environment in Northwest China in July, September and December 2020. Subsequently, six DSE strains were selected to test the growth and metabolic response of DSE strains to drought stress in vitro. The sampled plants and seasons significantly influenced the morphology, colonization and species diversity of DSE. Of the 15 DSE species isolated in the roots of these plants, Triangularia allahabadensis was reported in desert ecosystems for the first time. DSE colonization was predominately affected by season and soil factors, while species composition was more corresponded to plant species. The composition of metabolites of DSE strains varied significantly due to levels of drought stress and DSE identity, which indirectly reflected the difference of their traits to respond to drought stress. This study confirmed the establishment of relationship between DSE and roots of xerophytic plants, and proved the drought tolerance of DSE in vitro, providing insight into the application of DSE to assist desert plants to resist drought.

Dark septate endophytes: mutualism from by-products?

Plant roots are abundantly colonized by dark septate endophytic (DSE) fungi in virtually all ecosystems. DSE fungi are functionally heterogeneous and their relationships with plants range from antagonistic to mutualistic. Here, we consider the role of by-product benefits in DSE and other root-fungal symbioses. We compared host investments against symbiont-derived benefits for the host plant and categorized these benefits as by-products or benefits requiring reciprocal investment from the host. By-product benefits may provide the variability required for the evolution of invested mutualisms between the host and symbiont. We suggest that DSE could be considered as 'a by-product mutualist transitional phase' in the evolution of cooperative mycorrhizal symbionts from saprotrophic fungi.

Characterization and biological activities of melanin pigment from root endophytic fungus, Phoma sp. RDSE17.

Melanins are high molecular weight hydrophobic pigments which have gained popularity for their role in virulence against different pathogens. In the present study, we isolated and characterized the melanin pigment produced by a dark septate endophyte fungus Phoma sp. RDSE17, which was associated with the roots of an indigenous Oryza sativa cv. 'Chakhao amubi' in Manipur, Northeast India. The biological properties of purified melanin from the fungus were evaluated for their antioxidant, antimicrobial and anticancerous activities. The pigment was extracted from Phoma sp. by alkaline-acid hydrolysis method and confirmed as melanin through physico-chemical tests and spectral (UV, FTIR, and EPR) analysis. The analyses of the elemental composition indicated that the pigment possessed a low percentage of nitrogen (N) contents, and therefore, would not fall under DOPA class of melanin. Exposure of the fungus to melanin pathway inhibitors revealed a positive melanin inhibition by tricyclazole, but not by kojic acid. Thus, the melanin from Phoma sp. may be a member of the DHN family. Moreover, the purified melanin showed high DPPH (1, 1-Diphenyl-2-picrylhydrazyl) free radical-scavenging activity with an EC50 of 69µg/mL and inhibited human lung cancer cell (A549 cells) proliferation at 80µg/mL. The present study demonstrates that melanin from Phoma sp. RDSE17 could be employed as a potential biological (antioxidant) and antimicrobial agent for inhibiting the growth of humans and phytopathogens.

Intraspecific Variation in Responses of a Montane Grass, Festuca thurberi, to Simulated Biological Invasion

High elevation plant populations, such as those found in sub-alpine meadows, are at the forefront of climate change and likely to experience novel interactions with migrating plants from lower elevations, including non-native species. Some of these non-native plants, particularly members of the Brassicaceae, produce secondary metabolites that have been shown to inhibit root fungi in other ecosystems. We conducted a growth experiment with plant leachates in order to evaluate the degree to which the dominant high elevation grass species, Festuca thurberi would be affected by future novel interactions with the non-native mustard, Thlaspi arvense, relative to a native mustard (Noccaea fendleri). We assessed growth, chlorophyll content, biomass, mortality, and percent colonization of arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) in different genotypes of F. thurberi exposed to leachates from native and non-native mustards as well as F. thurberi leachate and a deionized (DI) water control. New growth and mortality varied more by genotype than by treatment with leachate of F. thurberi, T. arvense, and N. fendleri. Treatment, genotype, and the treatment × genotype interaction all had significant effects on chlorophyll content, with N. fendleri treatments demonstrating higher relative greenness levels than control treatments. Percent of fine roots with dark septate endophytes was significantly affected by individual genotype and treatment × genotype interaction, but there were no effects of treatment, genotype, or their interaction on percent root colonization by arbuscules or vesicles. Overall, we show that performance of a dominant high-altitude grass species varies in its response to the presence of an expanding, non-native plant, which may become increasingly common due to climate change.

Evaluation and management of soil microbial potentialities for improving the carob tree tolerance to water constraints

The carob tree (Ceratonia siliqua L.), an ecological, cultural and industrial component of the Mediterranean basin, has been experiencing a decline of its abundance in recent decades. Three contributing factors have been identified, an agricultural policy in favour of other plant species, an increasing urbanisation of the Mediterranean coastline, which leads to habitat fragmentation, and negative climatic conditions, notably longer periods of drought. The dependency of the carob tree on water resources is an underestimated trait, and yet a crucial one for its survival. The optimisation of the symbiotic association between carob and mycorrhizal fungi has been proposed as a promising strategy to improve its resistance to water stress. However, a more holistic view of plant-microorganism interactions within the environment seems essential to sustainably address the challenges of plant adaptation to environmental stresses. The central hypothesis of the thesis is that the management of interactions between the carob tree and the microbiota of some pioneer plants in its habitat could be the key for a better adaptation of the carob tree to drought. The objectives were (i) to assess the specificity of microbiota associated with plants living with the carob, and (ii) to quantify their impact on carob growth and resistance to water deficit. The results showed a predominance of actinobacteria, proteobacteria and ascomycetes in the studied habitats, with significant functional divergences between North and South of Morocco. Common garden experiments revealed that the type of microbiota was a major driver of the effect on carob growth and resistance, with strong variations depending on the water status. Indeed, the native microbiota of the carob tree is one of the most efficient under non-limiting water conditions but confers little resistance to drought. On the other hand, the microbiota associated with the lentisk provides the best growth-resistance trade-off. This benefit seems to be attributable to a higher abundance of DSE (dark septate endophytes) fungi and an increase in mycorrhizal colonisation in response to water stress. The integration of lentisk in technical practices as a lever for the management of a beneficial microbiota could therefore represent a future strategy for the adaptation of carob to increasing drought in the Mediterranean basin.

Dual inoculation of dark septate endophytes and Trichoderma viride drives plant performance and rhizosphere microbiome adaptations of Astragalus mongholicus to drought.

SummaryRhizosphere microbiome adapts their structural compositions to water scarcity and have the potential to mitigate drought stress of plants. To unlock this potential, it is crucial to understand community responses to drought in the interplay between soil properties, water management and exogenous microbes interference. Inoculation with dark septate endophytes (DSE) (Acrocalymma vagum, Paraboeremia putaminum) and Trichoderma viride on Astragalus mongholicus grown in the non‐sterile soil was exposed to drought. Rhizosphere microbiome were assessed by Illumina MiSeq sequencing of the 16S and ITS2 rRNA genes. Inoculation positively affected plant growth depending on DSE species and water regime. Ascomycota, Proteobacteria, Actinobacteria, Chloroflexi and Firmicutes were the dominant phyla. The effects of dual inoculation on bacterial community were greater than those on fungal community, and combination of P. putaminum and T. viride exerted a stronger impact on the microbiome under drought stress. The observed changes in soil factors caused by inoculation could be explained by the variations in microbiome composition. Rhizosphere microbiome mediated by inoculation exhibited distinct preferences for various growth parameters. These findings suggest that dual inoculation of DSE and T. viride enriched beneficial microbiota, altered soil nutrient status and might contribute to enhance the cultivation of medicinal plants in dryland agriculture.

Effects of Phosphorus on Cadmium Tolerance and Accumulation in a Dark Septate Endophyte

This study evaluated the effects of different phosphorus (P) concentrations on the growth of the dark septate endophyte (DSE)-Exophiala pinsciphila strain (ACCC 32496) under cadmium stress (100 mg L-1). Also evaluated were the mineral nutrient contents (calcium, magnesium, nitrogen, phosphorus, and sulfur) and cadmium accumulation in the fungus. The mycelial mineral contents (Ca, Mg, S) and the culture media pH at low P concentrations (0.37-3.64 mmol L-1) were higher than at high P conditions (18.35-36.7 mmol·L-1). The highest biomass, P content, and Cd content and accumulation in mycelium were obtained at high (18.35-36.7 mmol·L-1) P conditions. The mycelial biomass and Cd contents were significantly positively correlated with the mycelial P content. We conclude that high P concentrations improve the P content of DSE mycelium, enhance Cd tolerance in DSE, and increase Cd accumulation in mycelium.

Lignocellulolytic enzyme potential of dark septate endophyte (dse) from Pinus merkusii roots in Dramaga Bogor Indonesia

The ability of Dark Septate Endophyte (DSE) derived from the roots of P. merkusii in decomposing organic matter is not much published. This study aims to determine the activity of lignolytic and cellulolytic enzymes, as well as the value of the cellulolytic index of Apls, isolates from P. merkusii roots taken from IPB Dramaga Bogor. Enzyme activity was tested by measuring the clear zone formed, while the cellulolytic index value was obtained by measuring the ratio of the clear zone formed around the colony. Data were analyzed descriptively. The results identified 10 isolates, 8 Apls isolates had potential enzyme activity that able to form clear zone, 5 isolates had lignolytic enzyme activity (Apls 1.4.1, Apls 2.3.1.1, Apls 3.4.2, Apls 2.1.1 and Apls 3.4 1.1) and 1 isolate had cellulolytic enzyme activity (Apls 3.1.3), and 2 isolates had lignocellulolytic enzyme activity (Apls 1.5.3 and Apls 3.4.3b), with the highest cellulolytic index value in Apls 1.5.3 isolates of 0,87 mm. 2 isolates had not lignocellulolytic enzymes activity (Apls 3.4.3 and Apls 3.1.4). The DSE roots of P. merkusii from IPB Dramaga Bogor had the potential for lignocellulolytic enzymes of 20 per cent of the total DSE found.