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Northern peatlands are often dominated by ericaceous shrub species which rely on ericoid mycorrhizal fungi (ERM) for access to organic sources of nutrients, such as nitrogen (N) and phosphorus (P), and host abundant dark septate endophytes (DSE). Relationships between hosts and fungal symbionts may change during deposition of anthropogenic N and P. We studied the long-term effects of N and P addition on two ericaceous shrubs, Calluna vulgaris and Erica tetralix, at Whim Bog, Scotland by analyzing fungal colonization of roots, enzymatic activity, and fungal species composition. Unexpectedly, the frequency of typical ERM intracellular colonization did not change while the occurrence of ERM hyphae tended to increase and DSE hyphae to decrease. Our findings indicate that altered nutrient limitations shift root associated fungal colonization patterns as well as affecting ericaceous root enzyme activity and thereby decomposition potential. Reduction of recalcitrant fungal biomass in melanized DSE may have implications for peatland C sequestration under nutrient addition.

In arid highland environments harsh conditions for vegetation establishment prevail. Plants in these environments develop different strategies to survive, including associations with fungal root endophytes. These associations may improve plant growth, helping plant resistance to adverse environments. The aim of this study was to determine the relationship among arbuscular mycorrhizal fungi (AMF), dark septate endophytes (DSE) and dominance degree of Poaceae in arid highlands of Argentine Puna. We studied AMF and DSE root colonization, and rhizospheric hyphal densities of dominant and subordinate grass species. Dual and positive associations between AMF and DSE prevailed. Dominant grasses had the highest levels of AMF and DSE root colonization. Dominant and intermediate grasses were associated with the highest values of rhizospheric hyphal density. In Puna highlands, the interactions among AMF, DSE and grasses suggest that fungal root endophytes may play a role in structuring grass communities by differentially improving the resistance to harsh conditions.

Pine wilt disease (PWD), a worldwide threat to pine forests, has caused tremendous damage to conifer forest in the world. However, little research has been conducted on the relationship between symbiosis functions of root associated fungi and pine wilt disease. In this study, we assessed the influence of seven ectomycorrhizal fungi (ECMF) and five dark septate endophytic fungi (DSE) on the growth traits and root morphology as well as the correlation of these parameters to the cumulative mortality and the morbidity rates in Pinus tabulaeformis Carr.showed the lowest cumulative mortality rates. We propose that the ECMF/DSE symbiosis enhanced the resistance of pine wilt disease via mitigation the dysfunction of water caused by PWN infection. Our research provided evidence that inoculation of ECMF/DSE could be a potential way for pine wilt disease prevention. To find highly efficient fungi for pine wilt disease management, more ECMF and DSE species should be tested.

Evidence accumulated in recent years supports the crucial role of remodeled cell walls (CWs) in enabling plants to adapt to environmental challenges. However, the metal tolerance and alleviation mechanisms involving the CWs by endophyte-plant interactions to toxic metals have not yet been elucidated. In the present study, these mechanisms are tested by exploring the maize (Zea mays) Cd tolerance by modifying its root CW structure via inoculation with a dark septate endophyte (DSE) fungus Exophiala pisciphila. Our present study demonstrates that the root CWs were the primary site for Cd accumulation, functioning as a sink for toxic Cd ions. Interestingly, E. pisciphila colonization significantly bioaugmented subcellular compartmentalization of maize roots and increased the Cd content of various CW subfractions through a significantly increased enzyme activity, e.g., pectin methylesterase, as well as an upregulated expression of genes involved in CW biosynthesis and changes in the contents of functional groups in pectin and hemicellulose 1 in response to Cd stress. Consequently, the enhanced Cd compartmentation in plant CWs by DSE lowers the entry of trace metals in the protoplast, thereby conferring the tolerant races of plants that can survive and thrive on metal-contaminated soils.

Secondary metabolites from the cultures of the dark septate fungal endophyte (DSE) Drechslera sp., isolated from the roots of rye grass (Lollium sp.) and cultured under different experimental conditions, are described here for the first time. The use of suberoylanilidehydroxamic acid (SAHA) and other histone deacetylase inhibitors as epigenetic modifiers in the culture medium was evaluated by LC/MS and LC/MS/MS. Several differences in the metabolite production were detected by means of supervised principal component analysis (PCA) of LC/MS data. The presence of the compounds in the culture medium or in the mycelium was compared. In order to confirm their structure, many of these natural products were isolated from a larger scale culture. These metabolites were characterized as prenylhydroxybenzoic acids and chromans, two compounds, one of each class were previously undescribed, prenylquinoids, diketopiperazines and macrosphelides. Some of the compounds, which were released to the medium, showed good antifungal activity, suggesting that these compounds could protect Lollium from fungal phytopatogens. The use of SAHA as an additive of the cultures also induced the release of hexosylphytosphyngosine to the culture medium. The biotransformation of the inhibitors was observed in addition to the production of antifungal metabolites, showing the ability of this endophytic strain to control xenobiotics. Fil: Siless, Gastón Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; Argentina Fil: Gallardo, Gabriela Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; Argentina Fil: Rodriguez, Maria Alejandra. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentina Fil: Rincon Galan, Yuliet Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; Argentina Fil: Godeas, Alicia Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentina Fil: Cabrera, Gabriela Myriam. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad de Microanálisis y Métodos Físicos en Química Orgánica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Unidad de Microanálisis y Métodos Físicos en Química Orgánica; Argentina

The root diameters as well as colonization and diversity of the root-associating fungi of Vaccinium oldhamii Miq. were investigated in order to obtain information on their mycorrhizal properties. The distal regions of roots had typical hair roots with diameters of less than 100 μm. Ericoid mycorrhizal fungi (ErMF) and dark septate endophytes (DSE) were frequently observed in the roots. Ascomycetes, particularly helotialean fungi, appeared to be dominant among the endophytic fungi of V. oldhamii roots. Furthermore, Rhizoscyphus ericae (Read) Zhuang & Korf and Oidiodendron maius Barron known as ErMF were detected more frequently than other fungal species.

Dark septate endophytes (DSE) ubiquitously colonize the roots of plants growing in extreme heavy metals (HMs)-contaminated soils. Little is known about the overall molecular response of DSE to excessive HMs. Therefore, RNA-seq was performed through Illumina Hiseq 2000 sequencing based on two cDNA libraries of the DSE strain Exophiala pisciphila, cultured under cadmium (Cd)-free and Cd-stressed conditions, and 21,376 unigenes were generated. In total, 575 differentially expressed genes (DEGs) were obtained. Approximately 40% of the DEGs (228 unigenes) were involved in 10 well-known HMs-tolerant pathways, conferring the extreme cadmium (Cd) tolerance of E. pisciphila, including metal ion binding and transportation, organic acid metabolism and transportation, reactive oxygen species (ROS) scavenging, redox homeostasis, transcription factors production, sulfate assimilation, DNA repair and cell wall integrity maintenance, etc. Our results indicate that integral tactics associated with the collaboration of extracellular and intracellular mechanisms contribute to the enhanced HMs tolerance of this fungus. This study represents the first investigation of the transcriptome of DSE under Cd stress, and our results provide valuable information for future molecular studies of HMs tolerance in fungi.

Mycorrhizal fungi are ecologically significant because they form relationships with the host plants and provide a better knowledge about the nutrition and growth of the plants. The present investigation was carried out in three sites to examine mycorrhizal colonization in twenty plants. Among the twenty plants, arbuscular mycorrhizal (AM) fungal and dark septate endophytes (DSE) colonization was found in 18 and 11 species, respectively. Dual association of AM fungi and DSE were found in 10 plants. The presence of only vesicles and aseptate hyphae were observed in Alternanthera dentata and Bambusa vulgaris. The arbuscular mycorrhizal colonization (%) was highest recorded in Eupatorium odoratum. Root length with DSE fungal structures (%) was maximum in A. dentata. A total of 16 AM fungal species was isolated from the three soil samples. There were five, eleven and eight species of AM fungi were found from three sites belonging to the spore of Acaulospora, Ambispora, Diversispora, Funneliformis, Glomus, Paraglomus, Rhizophagus and Sclerocystis. This study revealed the wide spread occurrence of AM fungi and DSE fungal association in the studied ecosystem.

Dark Septate Endophytes (DSE) is a diverse group of Ascomycetes that colonize the roots of a wide range of plants species. They can be found in all ecosystems, from deserts to the tropics, but also in agroecosystems associated to the crops. Despite the ubiquitous of these fungi, only a few major crops were assessed for this association in field conditions. In general terms, a complex consortium of DSE fungi were observed to colonize the roots of some crops. In this work we study the DSE community associated to soybean in the most productive area of this crop in Argentina. We hypothesized that DSE root colonization level, and the identity/frequency of the isolates switch according to the growth stage of the crop. A total of 34 dark fungal colonies were isolated from two growth stages, being only six isolates asyntomatic in the resynthesis assay. Some taxa as Boeremia sp., Cadophora sp., Coniothyrium sp., Corynespora cassicola, Peyronellaea sp. and Phaeosphaeria sp. were exclusively isolated from seedlings, supporting the hypothesis of DSE fungal consortium switching. The soybean pathogens Corynespora cassicola and Macrophomina phaseolina were isolated from young and mature plants respectively. Additional studies should focus on a fine analysis of the dynamics of these fungi, considering also the driving factors that could determine these changes. To understand these mechanisms may be fundamental for a better sustainable management of the crop. Fil: Rothen, Carolina Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentina Fil: Miranda, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentina Fil: Aranda Rickert, Adriana Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentina Fil: Fracchia, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentina Fil: Rodríguez, M.A.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Microbiología del Suelo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentina

Dark septate endophytes (DSEs) are a heterogeneous group of endophytic fungi that frequently colonize the roots of plants growing in trace metal element-contaminated soils. However, the functional role of DSEs in host plants growing in metal-stressed environments remains to be elucidated. In this study, two DSE strains of Phialophora mustea Neerg. (K36 and Z48) were separately inoculated in tomato (Lycopersicon esculentum Miller) seedlings under metal stress conditions (0, 5, 10 mg kg−1 Cd or 0, 300, 600 mg kg−1 Zn) to evaluate the effects of DSE inoculation on tomato seedlings in pot cultures. The results showed that DSE colonization increased tomato seedling biomass whether or not there was metal addition. DSE-inoculated tomatoes had a lower Cd and Zn accumulation in both the shoots and roots compared with their respective non-inoculated controls. Under metal stress conditions, DSE inoculation significantly enhanced the activities of antioxidant enzymes, such as superoxide dismutase (SOD) and peroxidase (POD), thus relieving the membrane lipid peroxidation damage caused by metal stress, and reduced the leaf malondialdehyde (MDA) concentrations more than that of the non-inoculated treatments. The results revealed that DSE enhanced metal tolerance and improved tomato plant growth, both by the reduced metal uptake into root and shoot accumulation and by the enhanced activities of antioxidant enzymes to eliminate reactive oxygen species (ROS) stress induced by excessive metals.

a b s t r a c t Green roof plants must survive hot and dry conditions in low nutrient artificial growing media. Although soil microorganisms such as arbuscular mycorrhizal fungi (AMF) can ameliorate these constraints by increasing water and mineral uptake, virtually nothing is known about the microbes associated with the roots of green roof plants. We determined levels of AMF and dark septate endophyte (DSE) colonization of plants grown for four years on an experimental green roof in Halifax, Nova Scotia. Green roof plant species included the forb Solidago bicolor, the grasses Danthonia spicata and Poa compressa and the suc- culent Sedum acre. We also assessed root colonization of these same species, as well as three additional succulents (Sedum spurium, Rhodiola rosea and Hylotelephium telephium), collected from their natural habi- tats. We further assessed the inoculum potential of a commercial green roof substrate before and after the introduction of host plants. Levels of AMF colonization were similar within plant species, regardless of collecting location (roof or field). All plant species were colonized except for the succulent S. acre, which is commonly utilized as a green roof plant. The commercial growing medium contained extremely low levels of viable AMF propagules, but this increased significantly after planting with Solidago. Con- versely, all species (from roof, field and bioassay) were well colonized by DSE, which appear to differ from the AMF with respect to their pattern of dispersal onto the green roof. Although the widespread use of non-mycorrhizal succulent species such as S. acre precludes the ecosystem services provided by the AMF symbiosis, the benefits of both succulent tissue and AMF could be obtained simultaneously with careful green roof plant selection.

We assessed the arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungal associations in 57 ferns and 3 lycophytes (belonging to 15 families in 39 genera) of different life forms (epiphytic, saxicolous and terricolous) occurring in Palni Hills of Western Ghats. Fungal symbiosis was absent in all the three lycophytes examined. Fifty-five of the 57 ferns (91.66 %) examined had AM and 37 (64.91 %) had DSE fungal association. This is the first report on AM and DSE fungal association for 22 and 30 species, respectively. In addition, AM morphology was evaluated for the first time in 34 species. Sixty-five percentage of the mycorrhizal ferns had intermediate-type AM and 19.30 % had typical Paris-type AM morphology. Both Paris- and intermediate-type AM morphologies were observed in 10.53 % of ferns. The root length colonized by AM and DSE fungal structures significantly varied among species, and a significant negative relation existed between the root length colonized by AM and DSE fungi.

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.

We examined the extent and type of arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungal associations in three lycophyte and 44 fern species collected from three different sites in the Kolli Hills, Eastern Ghats, southern India. Of the 47 plant taxa (belonging to 21 families and 33 genera) examined, 46 had AM fungal and 33 had DSE fungal associations. But, fungal structures were absent in the aquatic fern Azolla pinnata (Azollaceae). This is the first report of AM and DSE fungal status for 16 and 28 species, respectively. Among terrestrial lycophytes and ferns, 26 species had dual association of both AM and DSE fungi, whereas 11 species had only AM fungal association. Vittaria elongata from epiphytic habitats had dual association of AM and DSE fungi. Likewise, Cheilanthes tenuifolia (saxicolous or terrestrial), Cheilanthes opposita, Lepisorus nudus, Pyrrosia lanceolata (terrestrial or epiphytic), and Asplenium lanceolatum (saxicolous or epiphytic) examined from different sites or habitats also had dual association of AM and DSE fungi. Seventy two percent of the mycorrhizal lycophytes and ferns had intermediate-type AM and 15 percent had both Paris- and intermediate-types at different sites. Significant variations in AM fungal structures were evident in 16 ferns occurring in two or more sites. Nine AM fungal spore morphotypes belonging to Acaulospora, Funneliformis, Glomus, Gigaspora, and Sclerocystis were found to be associated with lycophytes and ferns.

Dark septate endophyte (DSE) fungi are the most frequent colonists on the roots of Salix caprea in highly metal-contaminated soils. The present study was performed to obtain insights into the physiology and potential role(s) of DSE fungi for Salix caprea growing in metal-enriched sites. Fungal isolates from S. caprea roots were identified using molecular methods, and tested for their tolerance and metal accumulation in axenic cultures. In addition, an inoculation experiment was performed to monitor the effects of the fungi on the metal uptake by the plant host. Fitness of S. caprea cuttings was assessed by photosynthetic pigment quantification and measurements of transpiration. Fungal isolates were identified as members of the Phialophora/Cadophora complex. They showed different levels of metal tolerance and maintained growth on metal-enriched media. In comparison to non-inoculated cuttings, the DSE-inoculated cuttings had lower leaf Cd content, and for isolates DB146 and DB148, also lower Zn concentrations. All DSE isolates increased the chlorophyll levels of the cuttings, with isolate DB146 also positively affecting the transpiration rate of S. caprea. Our findings suggest that DSE reduced the metal uptake by the S. caprea cuttings, thus suggesting a beneficial role for S. caprea in metal-enriched soils.

International audience; Belowground interactions between plants and microorganisms are involved in numerous ecosystems processes such as carbon and nutrient cycling. Understanding their responses to on-going climate warming is thus of paramount importance to better predict future ecosystem functioning. We hypothesized that climate warming alters the interactions between Sphagnum litter phenolics and the fungal root symbiosis of the Ericale plant Andromeda polifolia in a Jura mountain peatland (France). We initiate a climate warming treatment (+1°C) in April 2008 in two microhabitats (lawns and hummocks). We measured polyphenolic contents, mycorrhizal and dark septate endophyte (DSE) root colonization, phenoloxidase and peroxidase activities in the A. polifolia rhizosphere from 2010 to 2012. We found that four years of warming modulated rhizospheric parameters (fungal root symbiosis and enzyme activities) of A. polifolia, but the response differed between microhabitats. Enzyme activities and fungal root colonization displayed different responses to warming according to the microhabitats. DSE root colonization increased and peroxidase activities decreased in warmed Hummocks while they remained stable in warmed lawns. We found a significant positive correlation between DSE root colonization and litter phenolics recovered in both microhabitats but only under in ambient conditions. On the contrary, significant negative correlation was observed between mycorrhizae and litter phenolics recovered in warmed plots while no relationship was found in control plots. Our work thus provides evidences that interplay between phenolics from Sphagnum litter and fungal symbiosis of an Ericale species in peatlands was affected by climate warming. It highlights different plant biological responses to climate warming according to peatland microhabitats and confirm that belowground activities are crucial to understand the response of peatlands to climate change.

We studied the arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungal associations in five species of pot-grown Asparagus (A. aethiopicus, A. densiflorus, A. setaceus, A. racemosus, and A. umbellatus). Root colonization by AM and DSE fungi and AM spore numbers in the soil were assessed. AM fungal diversity indices like species richness, Shannon-Weiner index, Simpson's index, evenness, and Jaccard's index were determined. Relationships among the fungal and soil variables were also examined. All the species of Asparagus examined were colonized by both AM and DSE fungi, and these associations have been reported for the first time in four species. Root colonization by both the fungi varied significantly among Asparagus species and was related to each other and soil factors. The AM colonization patterns reported in four Asparagus species for the first time were characterized by either intermediate or Arum-Paris type. The AM fungal community was dominated by members belonging to the Glomerales and was significantly influenced by Asparagus species and soil factors. We conclude that Asparagus species could support a diverse AM fungal community even under pot conditions; however, certain AM fungal species are sensitive to changes in soil factors and host species.

Plant roots in natural ecosystems are colonized by a diverse group of fungi among which the most common and widespread are arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungi. Though AM and DSE fungal associations are well reported for terricolous plant species, they are rather poorly known for lithophytic plant species. In this study, we examined AM and DSE fungal association in 72 non-orchidaceous vascular plant species growing as lithophytes in Siruvani Hills, Western Ghats of Tamilnadu, India. Sixty-nine plant species had AM and 58 species had DSE fungal associations. To our knowledge, we report AM fungal association in 42 and DSE fungal association in 53 plant species for the first time. There were significant differences in total root length colonization and root length colonized by different AM and DSE fungal structures among plant species. In contrast, the differences in AM and DSE fungal colonization among plants in various life-forms and lifecycles were not significant. AM morphology reported for the first time in 56 plant species was dominated by intermediate type AM morphology. A significant negative relationship existed between total root length colonized by AM and DSE fungi. These results clearly suggest that AM and DSE fungal associations are widespread in lithophytes.

The root diameters as well as colonization and diversity of the root-associating fungi of Vaccinium oldhamii Miq. were investigated in order to obtain information on their mycorrhizal properties. The distal regions of roots had typical hair roots with diameters of less than 100 μm. Ericoid mycorrhizal fungi (ErMF) and dark septate endophytes (DSE) were frequently observed in the roots. Ascomycetes, particularly helotialean fungi, appeared to be dominant among the endophytic fungi of V. oldhamii roots. Furthermore, Rhizoscyphus ericae (Read) Zhuang & Korf and Oidiodendron maius Barron known as ErMF were detected more frequently than other fungal species.

Abiotic stress is one of the major limiting factors for plant development and productivity, which makes it important to identify microorganisms capable of increasing plant tolerance to stress. Dark septate endophytes can be symbionts of plants. In the present study, we evaluated the ability of dark septate endophytes isolates to reduce the effects of water stress in the rice varieties Nipponbare and Piauí. The experiments were performed under gnotobiotic conditions, and the water stress was induced with PEG. Four dark septate endophytes were isolated from the roots of wild rice (Oryza glumaepatula) collected from the Brazilian Amazon. Plant height as well as shoot and root fresh and dry matter were measured. Leaf protein concentrations and antioxidant enzyme activity were also estimated. The dark septate endophytes were grown in vitro in Petri dishes containing culture medium; they exhibited different levels of tolerance to salinity and water stress. The two rice varieties tested responded differently to inoculation with dark septate endophytes. Endophytes promoted rice plant growth both in the presence and in the absence of a water deficit. Decreased oxidative stress in plants in response to inoculation was observed in nearly all inoculated treatments, as indicated by the decrease in antioxidant enzyme activity. Dark septate endophytes fungi were shown to increase the tolerance of rice plants to stress caused by water deficiency.

Species composition and diversity of arbuscular mycorrhizal fungi (AMF) in three Solanum species (Solanum khasianum, Solanum sisymbriifolium, and Solanum torvum) were investigated. The extent of AMF colonization was highest in S. sisymbriifolium and lowest in S. torvum, whereas, AMF spore density in the rhizosphere soil was lowest in S. sisymbriifolium and highest in S. torvum. Low percentage of dark septate endophyte (DSE) was also observed in all the species. A total of 24 AMF species belonging to four genera (Acaulospora, Glomus, Gigaspora, and Scutellospora) were isolated and identified from the rhizosphere soils. S. khasianum harbored 12 AMF species, while S. sisymbriifolium and S. torvum contained 11 AMF species each. Glomus and Acaulospora were the most frequently encountered AMF species. These findings indicate that Solanum species are rich in AM fungal diversity, and selection and inoculation of appropriate microbial strains could be of great value in improving the quality and quantity of plant material.

A survey of 35 tree species (belonging to 28 genera in 19 families) in Aliyar, South India was carried out to ascertain their arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungal status. All the tree species examined had AM association. AM and DSE colonization is reported for the first time in 20 and 14 species respectively. Cooccurrence of AM and DSE was observed in 14 (40%) tree species. The extent of DSE colonization was inversely related to the extent of AM fungal colonization. Six tree species had Arum-type, 18 had intermediatetype and 11 had typical Paris-type AM morphology. AM fungal spore morphotypes belonging to 11 species in two genera were isolated from the rhizosphere soil. AM fungal spore numbers were not related to the extent of AM colonization and Glomus dominated spore diversity. AM association individually and along with DSE were found respectively in the 63% and 44% of the economically important tree species. The occurrence of AM and DSE fungal association in economically important indigenous tree species indicates the possibility of exploiting this association in future conservation programmes of these species.

A survey on the endorhizal status of 39 fruit crops of 25 families, indicated that 22 fruit crops had arbuscular mycorrhizal (AM)–, four had dark septate endophyte (DSE)–fungal association, and 13 had dual colonization of AM and DSE fungi. Fruit crops were capable of forming Arum-, Paris-, or intermediate-types of AM morphologies of which intermediate-type was common. To our knowledge, we report for the first time AM in 10 fruit crops and DSE-fungal association in 17 fruit crops. The extent of AM- and DSE-fungal colonization ranged from 41% to 98% and < 1% to 89.9%, respectively, in different fruit crops. Arbuscular mycorrhizal–fungal spore numbers in the rhizosphere ranged from 6 to 61 spores per 25 g of soil. Arbuscular mycorrhizal–fungal spores belonging to Acaulospora, Glomus, and Scutellospora were isolated from the rhizosphere soil.

We investigated the colonization status of mycorrhizal and endophytic fungi in roots of plants established on an acidic barren at volcano Esan, Hokkaido, Japan. In total, 87 individuals of 21 plant taxa were investigated in four different vegetation sites and the surrounding area. Ericaceous plants such as Empetrum nigrum var. japonicum, Ledum palustre var. diversipilosum, Vaccinium vitis-idaea var. minus and Loiseleuria procumbens were the main colonizers at the study sites and dominated under even the most severe conditions of low soil moisture and nutrient content. They were associated with ericoid mycorrhizal (ERM) fungi at all vegetation sites and erratically with dark septate endophytic (DSE) fungi. They commonly associated together with arbuscular mycorrhizal (AM) fungi only at sites where Sasa senanensis dominated. Among the ericaceous plants, only Enkianthus campanulatus associated with AM and DSE fungi and had no associations with ERM fungi. Other herbaceous and woody plants associated commonly with AM or erratically with DSE fungi, except for Carex sp. and Polygonum spp. which erratically associated with AM and DSE fungi. Mycorrhizal associations were common in representative vegetation on the crater basin of Mt. Esan. In particular, ERM associations might play a significant role in invasion and establishment of ericaceous plants, and also in the development of plant communities in the harsh environment at Mt. Esan.

Dark septate endophytes (DSEs) live asymptomatically in the roots of vascular plants, are common in arctic and alpine areas, and are thought to play a quasimycorrhizal role. It is not known, however, whether they precede or arrive with their hosts. Previously reported enzymatic abilities of Phialocephala fortinii suggest that DSEs can live on organic debris in the soil, but there is little direct or experimental evidence for this. Phialocephala fortinii , Leptodontidium orchidicola , Cadophora melinii , Cadophora luteo-olivacea , and Lecythophora sp. were inoculated onto autoclaved Hylocomium splendens gametophytes and incubated for 3 months to determine if they degrade this organic material based on observations made using light and scanning electron microscopy. All fungi were able to colonize the bryophyte tissue to some extent. Lecythophora sp. and L. orchidicola penetrated cells by forming bore holes. Cadophora luteo-olivacea and P. fortinii were also observed inside cells, but bore holes through bryophyte cell walls were not observed. Cadophora melinii sporulated and grew abundantly on the surface of gametophytes but did not appear to penetrate cell walls. Phialocephala fortinii and L. orchidicola formed sclerotia in the gametophytes similar to those formed in roots. These results suggest that DSE fungi can persist and produce propagules, i.e., sclerotia and conidia, in the absence of host roots. These observations support the hypothesis that DSE fungi are able to precede their hosts during primary succession events.

A total of 91 isolates of dark septate endophytes( DSE) were isolated from the family Ericaceae plants. InternalTranscribed Spacer (ITS) and 5.8S rDNA sequence were determined in 10 non-pathogenic isolates of DSE,including a Heteroconium chaetospira. The determined sequences were subjected to Neighbor-joining analysis ofMEGA4. We identified Heteroconium chaetospira( syn. Cladophialophora chaetospira) on the first time in Japanfrom Ericaceae plant. Three isolates had a close relationship with Leptodontidium orchidicola. Identities of nonDSE isolates like Pj029 and Ro034 were still unknown and remain so until isolates sporulate or until more taxawill be sequenced. Strong bootstrap support within the phylogenetic tree between the Pleosporales isolates andPj022 confirmed their congeneric status, while Ro24 and Ro012 were exhibited close affinity to Cyphellophora sp.All DSE isolates had the ability to form intercellular structures within the epidermal cells of blueberry( Vacciniumcorymbosum L.).

Melanin produced by a dark septate endophyte, Exophiala pisciphila, was isolated and purified. The solubility properties, Ultraviolet–visible and Fourier transform infrared spectra of the purified E. pisciphila melanin were similar to those of typical melanin. Inhibition of melanin production was observed when colonies exposed to tricyclazole (1,8-dihydroxynaphthalene (DHN) melanin inhibitor), but not to kojic acid (3,4-dihydroxyphenylalanine melanin inhibitor). Thus the E. pisciphila melanin was a member of DHN melanin family. In addition, the antioxidant activities of E. pisciphila melanin were evaluated in vitro by 1,1-diphenyl-2-picryl-hydrazyl radical-scavenging assay. E. pisciphila melanin exhibited a strong antioxidant activity. Addition of 50–350 mg L−1 Cd(II) to the medium increased the melanin production in E. pisciphila.

O objetivo deste trabalho foi avaliar a ocorrência de fungos endofíticos "dark septate" (DSEF) em Oryza glumaepatula, na Amazônia, e sua capacidade de colonização in vitro. Foram coletadas plantas de O. glumaepatula em área de cerrado e de mata em Roraima. As raízes foram tratadas para a observação de hifas melanizadas septadas e de microescleródios. Os fungos foram isolados em meio ágar malte. Os DSEF foram observados em plantas coletadas em ambos os ambientes, com maior colonização nas coletadas da mata. Um isolado foi capaz de colonizar o hospedeiro original e também plantas de Oryza sativa, exibindo as estruturas características de DSEF em plantas de arroz saudáveis. The objective of this work was to assess the occurrence of dark septate endophyte fungi (DSEF) in Oryza glumaepatula in Amazonia, and its in vitro colonization capacity. Oryza glumaepatula plants were collected in forest and cerrado areas of the Roraima state, Brazil. The roots were prepared to observe septate melanized hyphas and microesclerotia. The isolation of fungi was done in agar malte medium. Dark septate endophyte fungi were observed in plants from both environments, with higher colonization on those collected in the forest. One isolate was able to colonize the original host and also Oryza sativa plants, exhibiting typical DSEF structures in rice healthy plants.

Arbuscular mycorrhizal fungi (AMF) and dark septate endophyte (DSE) associations were studied in 36 medicinal plant species from 33 genera and 17 families, collected from the Botanical Garden of the Jagiellonian University in Kraków. Arbuscular mycorrhiza (AM) was found in 34 species (94%); 26 were of the Arum-type, 4 – Paris and 4 taxa revealed intermediate morpho­logy. The abundance of AMF hyphae in roots varied with particular species, ranging from 2.5% (Helianthus tuberosus) to 77.9% (Convallaria majalis). The mycelium of DSE was observed in 13 plant species (36%), however, the percentage of root colonization by these fungi was low. Spores of 7 AMF species (Glomeromycota) were isolated from trap cultures established from rhizosphere soils of the investigated plants: Archaeospora trappei (Archaeosporaceae), Glomus aureum, Glomus caledonium, Glomus claroideum, Glomus constrictum, Glomus mosseae, Glomus versiforme (Glomeraceae). Our results are the first detailed report of root endophyte associations of the plant species under study. Moreover, the mycorrhizal status of 14 plant species is reported for the first time.

We examined arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungal association in 50 south Indian grasses from four different sites. AM fungal diversity was also compared among the different sites. Forty-four of the 50 grasses examined had AM association and dual association with DSE fungi occurred in 25 grasses. We report for the first time AM and DSE fungal status in 23 and 27 grasses respectively. Arum-type AM morphology was the dominant occurring in 21 grasses with typical Paris-type colonization occurring in 6 grasses. AM morphology is reported for the first time in 35 grasses. Over the different sites, spore density in the soil ranged from 5–22 per 100 g air-dried soil. Spores of 11 AM fungal taxa were isolated from the soil samples of grasses of which nine belonged to Glomus, one to Acaulospora and one to Scutellospora. No significant relationship existed between AM fungal colonization and spore numbers. Species richness was high in site II and Glomus aggregatum, Glomus viscosum and Glomus mosseae were most frequent species at different sites. Overall species diversity indices (Simpson index, Shannon-Weaver index, species equitability index) differed significantly between sites.

Changes in plant–fungal interactions were often suggested as one of possible mechanisms behind facilitative plant–plant effects in harsh environments. We asked how the mycorrhizal and dark septate endophyte (DSE) colonisations of understorey crowberry ( Empetrum nigrum ssp. hermaphroditum ) are affected by proximity to mature mountain birch trees ( Betula pubescens ssp. czerepanovii ) along three abiotic stress gradients (pollution, elevation, seashore) in the Kola peninsula, NW Russia. Stress level affected shoot growth and reproduction in crowberry, but had no effect on root fungal colonisation. In contrast, proximity to a mountain birch tree had no effect on either growth or reproduction of crowberry, but changed all characteristics of root colonisation. The mycorrhizal coil colonisation of crowberry was on average 21% higher near a birch tree, whereas other parameters were higher outside of canopy area (hyaline hyphae: 12%; DSE hyphae: 16%; DSE sclerotia: 42%). Effects of birch tree on root fungal colonisation in crowberry did not depend on the level of abiotic stress. Although we detected a weak positive association between growth of crowberry and its mycorrhizal coil colonisation, we conclude that mycorrhizal and DSE colonisations of crowberry are primarily affected by the abiotic environment. None of the detected patterns was consistent with the patterns expected from the theories concerning stress effects on plant–plant interactions.

To address paucity of the mycorrhizal studies in bamboo, we have investigated arbuscular mycorrhizal fungal (AMF) distribution and dark septate endophyte (DSE) colonization on four species of bamboo from Northeast India. Bambusa tulda exhibits Arum type of AMF morphology, and other bamboo species have Paris type. AMF colonization was significantly higher than DSE colonization (P

Since mycorrhizal symbionts are dependent on host carbon availability, shading and grazing of the host plant often decrease mycorrhizal colonization in host roots. We conducted field experiments on an intensively mycorrhizal host, Autumn gentian, Gentianella amarella to investigate the effects of neighbor removal and simulated grazing on host growth and reproduction as well as mycorrhizal colonization. In the neighbor removal experiment, we manually removed the above-ground parts of companion plants of gentians. Reduced competition tended to improve the performance of both the host and the symbionts. Total fungal as well as arbuscular, hyphal, and coiled hyphal colonizations were higher in gentians with neighbors removed. Simulated grazing (clipping off 50% of shoot height) reduced host shoot and seed biomass, whereas the responses of the root symbionts were most often positive or neutral. In the first experiment (with late-flowering plants), clipping increased arbuscular, hyphal, and total colonizations but decreased dark septate endophyte colonization. In the second experiment (with both early- and late-flowering plants), clipping did not affect total mycorrhizal colonization. Higher arbuscular, hyphal, and total colonizations were found in late-flowering gentians compared to early-flowering ones. Early-flowering plants, on the other hand, tolerated simulated grazing better compared to late-flowering plants, which may indicate a higher cost of the symbionts for the late-flowering plants. Above-ground herbivory tends to increase carbon limitation, and under these conditions, regrowing shoots and the fungal symbionts may appear as alternative, competing sinks for the host’s limited carbon reserves.

Associations of arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungi with 38 ginger species (Zingiberaceae) and two spiral gingers (Costaceae) were investigated. All species were mycorrhizal, and the status of 35 gingers and one spiral ginger has been investigated for the first time. The extent of AM colonization and the root length colonized by AM structures varied significantly among species. AM structures were also observed in non-root portions such as scale leaves. Arbuscular mycorrhizae were of either Arum-type or intermediate- type; AM-type is reported for the first time in 37 species. Spores of 16 morphotypes belonging to 4 genera ( Glomus , Acaulospora , Scutellospora , Racocetra ) were identified from the rhizosphere soil. DSE colonization was found in 22 gingers and 2 spiral gingers. Twenty-two plant species are reported as hosts of DSE fungi for the first time. The extent of total AM and DSE colonization was not correlated.

We compared arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungal associations in 2 crops and 31 weeds commonly occurring in pulp and paper mill effluent irrigated and well-water irrigated soils. Soil pH, organic C, N, P and K, were higher in pulp and paper mill effluent irrigated than in well-water irrigated soils. In contrast, the average AM fungal colonization, root length with AM fungal hyphae/hyphal coils, spore numbers and diversity were lower in pulp and paper mill effluent irrigated soils compared to well-water irrigated soils. However, no significant variation was found in DSE fungal colonization nor root length with AM fungal arbuscules/arbusculate coils and vesicles between pulp and paper mill effluent irrigated and well-water irrigated soils. A significant negative correlation existed between AM and DSE fungal colonization in both effluent and well-water irrigated soils. Twelve AM fungal spore morphotypes belonging to Acaulospora, Dentiscutata, Glomus, Racocetra and Scutellospora were isolated from the well-water irrigated soils, whereas spores of six morphotypes were isolated from effluent irrigated soils. AM fungal spore numbers were correlated significantly and positively to AM fungal colonization in effluent and well-water irrigated soils.

We analyzed mycorrhizal types and dark septate endophyte (DSE) fungal associations in a shola vegetation of Western Ghats region, southern India. Plants belonging to 29 species of 19 families were assessed for mycorrhizal type and DSE fungal association. Five mycorrhizal classes were classified based on morphological traits: arbuscular, ecto-, ectendo-, ericoid-, and orchid mycorrhizas. Arbuscular mycorrhizal (AM) association was the most predominant mycorrhizal type, occurring in 16 plant species, followed by orchid (3 species), ericoid- (2 species), and ecto- and ectendomycorrhizas (1 species each). Mycorrhizal association is reported for the first time in 19 plant species. DSE fungal association was found in six plant species. Arum- and Paris-type AM morphology was found, respectively, in 10 and 5 plant species, with intermediate type recorded in one species. In this study, some new records on the morphological types of AM in some plant families were obtained. Further occurrence of ectendomycorrhizas in Pinus oocarpa and dark septate fungal association in Eleaocarpus munronii, Symplocos cochinchiensis, Daphniphyllum neilgherrense, Euodia roxburghiana, Syzygium arnottianum, and Syzygium montanum are reported for the first time. Roots of Berberis tinctoria, Mahonia leschenaultii (Berberidaceae), Elaeagnus latifolia (Elaeagnaceae), and Elaeocarpus oblongus (Elaeocarpaceae) lacked any fungal structures.

Effect of disturbance on root colonization and vertical distribution of arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE) was investigated at two adjacent sites of Lal Suhanra Biosphere Reserve, Pakistan. Disturbance clearly affected AMF and DSE colonization, vertical distribution of AMF and plant community structure. Mean colonization of AMF and DSE was slightly less at the disturbed site. Average spore densities, diversity and richness of AMF and DSE were higher at the undisturbed site. A study of the vertical distribution of AMF associated with the five plant species most common to each study site indicated that beside AMF and DSE colonization disturbance may affect AMF species composition. Correlation of AMF with DSE is also discussed.

Arbuscular mycorrhizal and dark septate endophyte associations of 31 medicinal plant species collected from the Garden of Medicinal Plants of the Faculty of Pharmacy, Jagiellonian University, Collegium Medicum in Krakow were investigated. Arbuscular mycorrhiza (AM) was found in 30 species; 23 were of the Arum-type, 5—Paris and 2 taxa revealed intermediate morphology. Many plants were strongly colonized by arbuscular mycorrhizal fungi (AMF). The mycelium of dark septate endophytes (DSE) was observed in 21 taxa. However, the percentage of root colonization by these fungi was low. Spores of 15 species of AMF (Glomeromycota) were found in the rhizosphere of the investigated plants. Our results are the first detailed report of both AMF and DSE associations of these plant species. The use of AMF and DSE during the process of medicinal plant cultivation for pharmaceutical purposes is discussed.

The evaluation of fungal root endophytes of two multizonal mountain plant species (Soldanella carpatica and Homogyne alpine) in relation to altitude was conducted. The comparison of root colonization by coarse arbuscular mycorrhizal fungi (AMF) and the fine AMF endophyte (Glomus tenue), as well as the presence of dark septate endophytes (DSE) were assessed along altitudinal gradients (1000–2050 m a.s.l.) on calcareous and non-calcareous substrata in the Tatra Mts. (Western Carpathians). Additionally, AMF species composition in the rhizosphere of the investigated plants was determined. Coarse AMF dominated over the fine endophyte in roots of S. carpatica and H. alpina. In the case of S. carpatica, there was a tendency for coarse AMF colonization decline with increasing altitude, while the reverse trend was observed for the fine endophyte. In contrast, the altitudinal patterns of the two types were opposite in H. alpina. Fifteen AMF species associated with the rhizosphere of S. carpatica were ident...

The effects of the interactions of soil filamentous fungi (including saprotrophic, mycorrhizal and endophytic fungi) on several morphological and physiological parameters of Norway spruce seedlings [Picea abies (L.) Karst.] were studied in a pot experiment. Both mycorrhizal variants (Hebeloma bryogenes and Cadophora finlandica) were slightly inhibited with respect to the accumulation of aboveground biomass. However, these variants exhibited significantly improved foliar content of N, P, and Ca (H. bryogenes variant also K), compared to controls. The presence of the saprotrophic fungus Setulipes androsaceus attenuated the positive effect of mycorrhizal fungi on Ca, P, and K content, but did not reduce the positive effect of mycorrhizal fungi on the N content of the seedlings’ needles. Raman spectroscopy revealed that both mycorrhizal fungi increased the foliar content of carotenoids compared to the controls, but the effect diminished in the presence of S. androsaceus. In contrast, in the presence of the dark septate endophyte Phialocephala fortinii, needles exhibited significantly higher wax content and lower carotenoid content compared to the mycorrhizal variants. The presence of the saprotrophic isolate Serpula himantoides resulted in a decrease in needle waxes in comparison to controls. The needles’ carotenoid concentration was positively correlated with the levels of needle nutrients (N, P, K, Ca, Mg), while correlation of needle nutrients (N, P) with the needle wax concentration was negative. We conclude that not only individual fungi but also their interactions profoundly affect the nutrition and needle composition of Norway spruce seedlings.

We examined the mycorrhizal type of 128 plant species in two patches of native vegetation of the Chaco Serrano Woodland, central Argentina, the largest dry forest area in South America. Of the 128 plant species investigated (belonging to 111 genera in 53 families), 114 were colonized by arbuscular mycorrhizal fungi (AM), orchid mycorrhizal associations were present in the five terrestrial orchid species analyzed, one ectomycorrhiza was only present in Salix humboldtiana Willd., and 96 harbored a dark septate endophyte (DSE) association. Co-occurrence of AM and DSE was observed in 88 plant species. We determine morphological types of arbuscular mycorrhizal fungi (Arum, Paris, and intermediate AM structures) and report the mycorrhizal status in 106 new species, 12 of which are endemic to central Argentina and two, Aa achalensis Schltr. and Buddleja cordobensis Griseb., are declared to be vulnerable species. Root colonization in the Chaco Serrano Woodland is widespread and should be considered in revegetation programs due to the deterioration of this particular ecosystem. Considering the predominance of AM and DSE associations and the various potential benefits that these associations may bring to plant establishment, they should receive special attention in conservation and reforestation of these woodlands. Fil: Fracchia, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Aranda Rickert, Adriana Marina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; Argentina Fil: Gopar, Analia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Silvani, Vanesa Analia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Fernandez Bidondo, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Godeas, Alicia Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

To understand the possible role of the plant root associated fungi on metal tolerance, their role in the uptake of heavy metals and the potential transfer of these metal ions to the plant, three strains of dark septate endophytic (DSE) fungi were isolated from a waste smelter site in southwest China, and one strain was isolated from a non-contaminated site. According to molecular phylogenetic analysis of the ITS 1-5.8S rDNA-ITS 2 gene regions and morphological characteristics, one is identified as Exophiala pisciphila, and the other three are non-sporulating fungi under the experiment condition with the nearest phylogenetic affinities to the Thysanorea papuana strain EU041814. Tolerance and accumulation abilities of the three DSE strains for metals were investigated in liquid culture. Minimum inhibitory concentrations (MIC) of Pb, Zn, and Cd were determined. It was demonstrated that the tolerance of the DSE strains varied between metal species and strains. The E. pisciphila strain is able to accumulate lead and cadmium over 20% and 5% of dry weight of biomass, respectively. Partial of the sequestrated metals can be washed with CaCh. Morphological and enzyme activity changes taking place in the presence of excessive Pb, Cd, and/or Zn also indicate that the mechanism of heavy metal tolerance and accumulation of the DSE strains would be a complex process. The findings indicated promising tolerance and accumulation of the DSE strains with potential values in metal cycling and restoration of soil and water system.

Fungi were isolated from the roots of 17 plant species from the families Apiaceae, Cunoniaceae, Cyperaceae, Droseraceae, Fabaceae-Mimosoideae, Lomandraceae, Myrtaceae, Pittosporaceae, Proteaceae and Stylidiaceae at a sclerophyll forest site in New South Wales, Australia. Internal transcribed spacer (ITS) restriction fragment length polymorphism (RFLP) and sequence comparisons indicated that the isolated fungi had affinities to a range of ascomycetes, basidiomycetes and zygomycetes. Four RFLP types had closest affinities to previously identified Helotiales ericoid mycorrhizal (ERM) or Oidiodendron spp. Isolates representing six RFLP types, which were variously isolated from all 17 plant species, formed ERM coils in hair root epidermal cells of Woollsia pungens (Ericaceae) under gnotobiotic conditions. Three of these isolates formed intercellular hyphae, intracellular hyphae and/or microsclerotia, which are typical of dark septate endophyte infection, in roots of Stylidium productum (Stylidiaceae), indicating an ability to form different types of association with roots of different hosts. Overall the data indicate that a broad range of plant taxa may act as repositories for ERM fungi in sclerophyll forest soil.

To determine the mycorrhizal status and to identify the fungi colonising the roots of the plants, common buckwheat (Fagopyrum esculentum) and tartary buckwheat (F. tataricum) were inoculated with an indigenous fungal mixture from a buckwheat field. Root colonisation was characterised by the hyphae and distinct microsclerotia of dark septate endophytes, with occasional arbuscules and vesicles of arbuscular mycorrhizal fungi. Sequences of arbuscular mycorrhizal fungi colonising tartary buckwheat clustered close to the Glomus species group A. Sequences with similarity to the Ceratobasidium/Rhizoctonia complex, a putative dark septate endophyte fungus, were amplified from the roots of both common and tartary buckwheat. To the best of our knowledge, this is the first report of arbuscular mycorrhizal colonisation in tartary buckwheat and the first molecular characterisation of these fungi that can colonise both of these economically important plant species.

A growing body of evidence suggests that plant root-associated fungi such as dark septate endophytes (DSE) can help plants overcome many biotic and abiotic stresses, of great interest is DSE-plant metal tolerance and alleviation capabilities on contaminated soils. However, the tolerance and alleviation mechanisms involved have not yet been elucidated. In the current study, the regulation and physiological response of Zea mays to its root-associated DSE, Exophiala pisciphila was analyzed under increased soil Cd stress (0, 10, 50, 100 mg kg−1). Under Cd stress, DSE inoculation significantly enhanced the activities of antioxidant enzymes and low-molecular weight antioxidants, while also inducing increased Cd accumulation in the cell wall and conversion of Cd into inactive forms by shoot and root specific regulation of genes related to metal uptake, translocation and chelation. Our results showed that DSE colonization resulted in a marked tolerance to Cd, with a significant decrease in cadmium phytotoxicity and a significant increase in maize growth by triggering antioxidant systems, altering metal chemical forms into inactive Cd, and repartitioning subcellular Cd into the cell wall. These results provide comprehensive evidence for the mechanisms by which DSE colonization bioaugments Cd tolerance in maize at physiological, cytological and molecular levels.

During an extended search in Western Canada for fungal root endophytes useful as biocontrol agents against soil-borne pathogens, we isolated Heteroconium chaetospira, as well as Phialocephala fortinii or similar taxa, from seven samples of forest soil using herbaceous seedlings of four different species (i.e., barley, Chinese cabbage, eggplant, and melon) as bait plants. Our results support a previous observation that eggplant is a particularly effective species for baiting H. chaetospira from soil and confirm the ability of this fungus to grow as an endophyte in the roots of axenically reared host plants. Cultural characters show that this species is similar to P. fortinii and other melanized fungi in the dark septate endophyte (DSE) group (e.g., Leptodontidium orchidicola, P. sphaeroides, and Cadophora finlandica) in that it produces darkly pigmented colonies on agar media. Heteroconium chaetospira differs from P. fortinii and other melanized members of the Leotiomycetes in the DSE group in that its conidia are fusiform and develop in blastic acropetal chains. Heteroconium chaetospira is phylogenetically distant from most DSE taxa because DNA sequences for the nuclear small subunit (SSU) ribosomal RNA gene (rDNA) indicate that the taxon is affiliated with the Herpotrichiellaceae of the Chaetothyriales rather than with the Leotiomycetes.