Pseudosigmoidea ibarakiensis sp. nov., a dark septate endophytic fungus from a cedar forest in Ibaraki, Japan

Importance of Dark Septate Endophytes in Agriculture in the Face of Climate Change

Climate change is a notable challenge for agriculture as it affects crop productivity and yield. Increases in droughts, salinity, and soil degradation are some of the major consequences of climate change. The use of microorganisms has emerged as an alternative to mitigate the effects of climate change. Among these microorganisms, dark septate endophytes (DSEs) have garnered increasing attention in recent years. Dark septate endophytes have shown a capacity for mitigating and reducing the harmful effects of climate change in agriculture, such as salinity, drought, and the reduced nutrient availability in the soil. Various studies show that their association with plants helps to reduce the harmful effects of abiotic stresses and increases the nutrient availability, enabling the plants to thrive under adverse conditions. In this study, the effect of DSEs and the underlying mechanisms that help plants to develop a higher tolerance to climate change were reviewed.

©Relationship between endophytic fungal diversity and colonization and soil factors of cultured blueberry roots in Guizhou Province, Southwest China

Dark septate endophytes (DSEs) inhabit plant roots and soil in ecosystems and host plants worldwide. DSE colonization is influenced by cultivars, soil factors, and specific habitat conditions. The regular diversity of DSEs in blueberries in Guizhou, China, is still unclear. In this study, four cultivars (Gardenblue, Powderblue, O'Neal, and Legacy) in three areas (Gaopo, Majiang, and Fenggang) in Guizhou were used to identify DSEs by morphological and molecular biological methods and to clarify the relationship between DSE diversity and DSE colonization and soil factors of cultivated blueberries in Guizhou. The DSEs isolated from cultivated blueberry roots in 3 areas in Guizhou Province were different, belonging to 17 genera, and the dominant genera were Penicillium, Phialocephala, and Thozetella. DSEs isolated from Majiang belonged to 12 genera and 16 species, those from Gaopo belonged to 7 genera and 15 species, and those from Fenggang belonged to 5 genera and 7 species. Among the different blueberry varieties, 11 genera were isolated from O'Neal, 12 genera were isolated from Powderblue, 11 genera were isolated from Legacy and 13 genera were isolated from Gardenblue. Coniochaeta is endemic to O'Neal, Chaetomium and Curvularia are endemic to Powderblue, and Thielavia is endemic to Legacy. Correlation analysis showed that DSE diversity was significantly correlated with DSE colonization and soil factors.

Novel Freshwater Ascomycetes from Spain

Freshwater ascomycetes are a group of fungi of great ecological importance because they are involved in decomposition processes and the recycling of organic matter in aquatic ecosystems. The taxonomy of these fungi is complex, with representatives in several orders of the phylum Ascomycota. In the present study, we collected ninety-two samples of plant debris submerged in freshwater in different locations in Spain. The plant specimens were placed in wet chambers and developed several fungi that were later isolated in pure culture. A main phylogenetic tree using the nucleotide sequences of D1-D2 domains of the 28S nrRNA gene (LSU) was built to show the taxonomic placement of all our fungal strains, and, later, individual phylogenies for the different families were built using single or concatenated nucleotide sequences of the most suitable molecular markers. As a result, we found a new species of Amniculicola that produces a coelomycetous asexual state, a new species of Elongatopedicellata that produces an asexual state, a new species of Neovaginatispora that forms both sexual and asexual states in vitro, and the sexual states of two species of Pyrenochaetopsis, none of which have been reported before for these genera. In addition, we describe a new species of Pilidium characterized by the production of copper-colored globose conidiomata, and of Pseudosigmoidea, which produces well-developed conidiophores.

Advances in the Role of Dark Septate Endophytes in the Plant Resistance to Abiotic and Biotic Stresses

Endophytic fungi have been studied in recent decades to understand how they interact with their hosts, the types of relationships they establish, and the potential effects of this interaction. Dark septate endophytes (DSE) are isolated from healthy plants and form melanised structures in the roots, including inter- and intracellular hyphae and microsclerotia, causing low host specificity and covering a wide geographic range. Many studies have revealed beneficial relationships between DSE and their hosts, such as enhanced plant growth, nutrient uptake, and resistance to biotic and abiotic stress. Furthermore, in recent decades, studies have revealed the ability of DSE to mitigate the negative effects of crop diseases, thereby highlighting DSE as potential biocontrol agents of plant diseases (BCAs). Given the importance of these fungi in nature, this article is a review of the role of DSE as BCAs. The findings of increasing numbers of studies on these fungi and their relationships with their plant hosts are also discussed to enable their use as a tool for the integrated management of crop diseases and pests.

Fungal Endophyte: An Interactive Endosymbiont With the Capability of Modulating Host Physiology in Myriad Ways

Endophytic fungi ubiquitously dwell inside the tissue-spaces of plants, mostly asymptomatically. They grow either intercellularly or intracellularly in a particular host plant to complete the whole or part of their life cycle. They have been found to be associated with almost all the plants occurring in a natural ecosystem. Due to their important role in the survival of plants (modulate photosynthesis, increase nutrient uptake, alleviate the effect of various stresses) they have been selected to co-evolve with their hosts through the course of evolution. Many years of intense research have discovered their tremendous roles in increasing the fitness of the plants in both normal and stressed conditions. There are numerous literature regarding the involvement of various endophytic fungi in enhancing plant growth, nutrient uptake, stress tolerance, etc. But, there are scant reports documenting the specific mechanisms employed by fungal endophytes to manipulate plant physiology and exert their effects. In this review, we aim to document the probable ways undertaken by endophytic fungi to alter different physiological parameters of their host plants. Our objective is to present an in-depth elucidation about the impact of fungal endophytes on plant physiology to make this evolutionarily conserved symbiotic interaction understandable from a broader perspective.

Nitrogen and phosphorus concentrations in growth media affect the relationship between root endophytic fungi and host plant

Endophytic fungi (EPF) colonize plant roots and enhance their growth. The relationship between host plant and EPF can be affected by several factors, such as growth media, host species, and fungal species. The objective of this study was to clarify the effect of nutrient concentration in growth media on the relationship between host plant and root EPF. Brassica campestris was grown in 1/100 Murashige and Skoog (MS), 1/10 MS, 1/100 MS and 1/10 nitrogen (high N), and 1/100 MS and 1/10 phosphorus (high P) media. B. campestris was inoculated with four root EPFs isolated from forest soils in Indonesia and harvested 28 days after transplant. Shoot dry weight (SDW) and colonization in roots were measured. All the isolates colonized roots of B. campestris. Two isolates increased the SDW of B. campestris grown on 1/100 MS media. The shoot growth response of B. campestris to EPF colonization on 1/100 MS was higher than that on 1/100 high N and 1/100 high P MS media. These results suggest that concentration of nitrogen and phosphorus in growth media determine the relationship between B. campestris and root EPF.

Dark septate endophytic fungi increase the activity of proton pumps, efficiency of 15N recovery from ammonium sulphate, N content, and micronutrient levels in rice plants

Plants colonised by dark septate endophytic (DSE) fungi show increased uptake of nutrients available in the environment. The objective of the present study was to evaluate the impact of DSE fungi on the activity of proton pumps, nitrogen (N) recovery from ammonium sulphate, and nutrient accumulation in rice plants. Treatments consisted of non-inoculated plants and plants inoculated with two isolates of DSE fungi, A101 and A103. To determine N recovery from the soil, ammonium sulphate enriched with 15N was added to a non-sterile substrate while parameters associated with the activity of proton pumps and with NO3- uptake were determined in a sterile environment. The A101 and A103 fungal isolates colonised the roots of rice plants, promoting 15N uptake, growth, and accumulation of nutrients as compared with the mock control. A103 induced the expression of the plasma membrane H+-ATPase (PM H+-ATPase) isoforms OsA5 and OsA8, the activity of the PM H+-ATPase and H+-pyrophosphatase. Our results suggest that the inoculation of rice plants with DSE fungi represents a strategy to improve the N recovery from ammonium sulphate and rice plant growth through the induction of OsA5 and OsA8 isoforms and stimulation of the PM H+-ATPase and H+-pyrophosphatase.

New and Interesting Fungi. 2

One order, seven families, 28 new genera, 72 new species, 13 new combinations, four epitypes, and interesting new host and / or geographical records are introduced in this study. Pseudorobillardaceae is introduced for Pseudorobillarda (based on P. phragmitis). New genera include: Jeremyomyces (based on J. labinae) on twigs of Salix alba (Germany); Neodothidotthia (based on N. negundinicola) on Acer negundo (Ukraine); Neomedicopsis (based on N. prunicola) on fallen twigs of Prunus padus (Ukraine); Neophaeoappendicospora (based on N. leucaenae) on Leucaena leucocephala (France) (incl. Phaeoappendicosporaceae); Paradevriesia (incl. Paradevriesiaceae) (based on P. americana) from air (USA); Phaeoseptoriella (based on P. zeae) on leaves of Zea mays (South Africa); Piniphoma (based on P. wesendahlina) on wood debris of Pinus sylvestris (Germany); Pseudoconiothyrium (based on P. broussonetiae) on branch of Broussonetia papyrifera (Italy); Sodiomyces (based on S. alkalinus) from soil (Mongolia), and Turquoiseomyces (incl. Turquoiseomycetales and Turquoiseomycetaceae) (based on T. eucalypti) on leaves of Eucalyptus leptophylla (Australia); Typhicola (based on T. typharum) on leaves of Typha sp. (Germany); Xenodevriesia (incl. Xenodevriesiaceae) (based on X. strelitziicola) on leaves of Strelitzia sp. (South Africa). New species include: Bacillicladium clematidis on branch of Clematis vitalbae (Austria); Cercospora gomphrenigena on leaves of Gomphrena globosa (South Africa); Cyphellophora clematidis on Clematis vitalba (Austria); Exophiala abietophila on bark of Abies alba (Norway); Exophiala lignicola on fallen decorticated trunk of Quercus sp. (Ukraine); Fuscostagonospora banksiae on Banksia sp. (Australia); Gaeumannomycella caricicola on dead leaf of Carex remota (Germany); Hansfordia pruni on Prunus persica twig (Italy) (incl. Hansfordiaceae); Microdochium rhopalostylidis on Rhopalostylis sapida (New Zealand); Neocordana malayensis on leaves of Musa sp. (Malaysia); Neocucurbitaria prunicola on fallen twigs of Prunus padus (Ukraine); Neocucurbitaria salicis-albae on Salix alba twig (Ukraine); Neohelicomyces deschampsiae on culm base of dead leaf sheath of Deschampsia cespitosa (Germany); Pararoussoella juglandicola on twig of Juglans regia (Germany); Pezicula eucalyptigena on leaves of Eucalyptus sp. (South Africa); Phlogicylindrium dunnii on leaves of Eucalyptus dunnii (Australia); Phyllosticta hagahagaensis on leaf litter of Carissa bispinosa (South Africa); Phyllosticta austroafricana on leaf spots of unidentified deciduous tree host (South Africa); Pseudosigmoidea alnicola on Alnus glutinosa leaf litter (Germany); Pseudoteratosphaeria africana on leaf spot on unidentified host (Angola); Porodiplodia vitis on canes of Vitis vinifera (USA); Sodiomyces alkalinus from soil (Mongolia), Sodiomyces magadiensis and Sodiomyces tronii from soil (Kenya), Sympodiella quercina on fallen leaf of Quercus robur (Germany) and Zasmidium hakeicola on leaves of Hakea corymbosa (Australia). Epitypes are designated for: Cryptostictis falcata on leaves of E. alligatrix (Australia), Hendersonia phormii on leaves of Phormium tenax (New Zealand), Sympodiella acicola on needles of Pinus sylvestris (Netherlands), and Sphaeria scirpicola var. typharum on leaf of Typha sp. (Germany). Several taxa originally described from rocks are validated in this study. New taxa include: Extremaceae fam. nov., and new genera, Arthrocatena, Catenulomyces, Constantinomyces, Extremus, Hyphoconis, Incertomyces, Lapidomyces, Lithophila, Monticola, Meristemomyces, Oleoguttula, Perusta, Petrophila, Ramimonilia, Saxophila and Vermiconidia. New species include: Arthrocatena tenebrosa, Catenulomyces convolutus, Constantinomyces virgultus, C. macerans, C. minimus, C. nebulosus, C. virgultus, Exophiala bonariae, Extremus adstrictus, E. antarcticus, Hyphoconis sterilis, Incertomyces perditus, Knufia karalitana, K. marmoricola, K. mediterranea, Lapidomyces hispanicus, Lithophila guttulata, Monticola elongata, Meristemomyces frigidus, M. arctostaphyli, Neodevriesia bulbillosa, N. modesta, N. sardiniae, N. simplex, Oleoguttula mirabilis, Paradevriesia compacta, Perusta inaequalis, Petrophila incerta, Rachicladosporium alpinum, R. inconspicuum, R. mcmurdoi, R. monterosanum, R. paucitum, Ramimonilia apicalis, Saxophila tyrrhenica, Vermiconidia antarctica, V. calcicola, V. foris, and V. flagrans.

Dark Septate Endophytic Fungi Increase Green Manure-15N Recovery Efficiency, N Contents, and Micronutrients in Rice Grains

An understanding of the interaction between rice and dark septate endophytic (DSE) fungi, under green fertilization, may lead to sustainable agricultural practices. Nevertheless, this interaction is still poorly understood. Therefore, in this study, we aimed to evaluate the accumulation of macro- and micronutrients, dry matter, and protein and N recovery efficiency from Canavalia ensiformis (L.)-¹⁵N in rice inoculated with DSE fungi. An experiment under greenhouse conditions was conducted in a randomized complete block design comprising split-plots, with five replicates of rice plants potted in non-sterilized soil. Rice (Piauí variety) seedlings were inoculated with DSE fungi, A101 and A103, or left uninoculated (control) and transplanted into pots containing 12 kg of soil, which had previously been supplemented with dry, finely ground shoot biomass of C. ensiformis enriched with 2.15 atom % ¹⁵N. Two collections were performed in the experiment: one at 54 days after transplanting (DAT) and one at 130 DAT (at maturation). Growth indicators (at 54 DAT), grain yield, nutrient content, recovery efficiency, and the amount of N derived from C. ensiformis were quantified. At 54 DAT, the N content, chlorophyll content, and plant height of inoculated plants had increased significantly compared with the control, and these plants were more proficient in the use of N derived from C. ensiformis. At maturation, plants inoculated with A103 were distinguished by the recovery efficiency and amount of N derived from C. ensiformis and N content in the grain and shoot being equal to that in A101 inoculation and higher than that in the control, resulting in a higher accumulation of crude protein and dry matter in the full grain and panicle of DSE-rice interaction. In addition, Fe and Ni contents in the grains of rice inoculated with these fungi doubled with respect to the control, and in A103 inoculation, we observed Mn accumulation that was three times higher than in the other treatments. Our results suggest that the inoculation of rice with DSE fungi represents a strategy to improve green manure-N recovery, grain yield per plant, and grain quality in terms of micronutrients contents in cropping systems with a low N input.

Dark Septate Endophytic Fungi Help Tomato to Acquire Nutrients from Ground Plant Material

Dark septate endophytic (DSE) fungi are facultative biotrophs that associate with hundreds of plant species, contributing to their growth. These fungi may therefore aid in the search for sustainable agricultural practices. However, several ecological functions of DSE fungi need further clarification. The present study investigated the effects of DSE fungi inoculation on nutrient recovery efficiency, nutrient accumulation, and growth of tomato plants fertilized with organic and inorganic N sources. Two experiments were carried out under greenhouse conditions in a randomized blocks design, with five replicates of tomato seedlings grown in pots filled with non-sterile sandy soil. Tomato seedlings (cv. Santa Clara I-5300) inoculated with DSE fungi (isolates A101, A104, and A105) and without DSE fungi (control) were transplanted to pots filled with 12 kg of soil which had previously received finely ground plant material [Canavalia ensiformis (L.)] that was shoot enriched with 0.7 atom % 15N (organic N source experiment) or ammonium sulfate-15N enriched with 1 atom % 15N (mineral N source experiment). Growth indicators, nutrient content, amount of nitrogen (N) in the plant derived from ammonium sulfate-15N or C. ensiformis-15N, and recovery efficiency of 15N, P, and K by plants were quantified 50 days after transplanting. The treatment inoculated with DSE fungi and supplied with an organic N source showed significantly higher recovery efficiency of 15N, P, and K. In addition, the 15N, N, P, K, Ca, Mg, Fe, Mn, and Zn content, plant height, leaf number, leaf area (only for the A104 inoculation), and shoot dry matter increased. In contrast, the only positive effects observed in the presence of an inorganic N source were fertilizer-K recovery efficiency, content of K, and leaf area when inoculated with the fungus A104. Inoculation with A101, A104, and A105 promoted the growth of tomato using organic N source (finely ground C. ensiformis-15N plant material).

Lulwoana sp., a dark septate endophyte in roots of Posidonia oceanica (L.) Delile seagrass

Posidonia oceanica is the most common, widespread and important monocotyledon seagrass in the Mediterranean Basin, and hosts a large biodiversity of species, including microorganisms with key roles in the marine environment. In this study, we ascertain the presence of a fungal endophyte in the roots of P. oceanica growing on different substrata (rock, sand and matte) in two Sicilian marine meadows. Staining techniques on root fragments and sections, in combination with microscope observations, were used to visualise the fungal presence and determine the percentage of fungal colonisation (FC) in this tissue. In root fragments, statistical analysis of the FC showed a higher mean in roots anchored on rock than on matte and sand. In root sections, an inter- and intracellular septate mycelium, producing intracellular microsclerotia, was detected from the rhizodermis to the vascular cylinder. Using isolation techniques, we obtained, from both sampling sites, sterile, slow-growing fungal colonies, dark in colour, with septate mycelium, belonging to the dark septate endophytes (DSEs). DNA sequencing of the internal transcribed spacer (ITS) region identified these colonies as Lulwoana sp. To our knowledge, this is the first report of Lulwoana sp. as DSE in roots of P. oceanica. Moreover, the highest fungal colonisation, detected in P. oceanica roots growing on rock, suggests that the presence of the DSE may help the host in several ways, particularly in capturing mineral nutrients through lytic activity.

The role of dark septate endophytic fungal isolates in the accumulation of cesium by chinese cabbage and tomato plants under contaminated environments

Following the 2011 Fukushima Daiichi Nuclear Power Plant accident, the preservation of the food chain from radionuclides contamination has become of crucial importance. The potential of Dark septate endophytic fungi in the management of Cs accumulation in plants under contaminated environments was investigated using Chinese cabbage and tomato plants. Four endophytic fungal isolates of different species, i.e. Pseudosigmoidea ibarakiensis I.4-2-1, Veronaeopsis simplex Y34, Helminthosporium velutinum 41-1, and as yet unidentified taxon 312-6 were tested In Vitro in two levels of Cs (5ppm and 10ppm). On the plant growth, the inoculation of the selected DSEs to both Chinese cabbage and tomato resulted in an increased biomass of up to 82% and 122%, respectively compared to control (non-inoculated) plants. With regards to the Cs accumulation, it varied with the host plant considered. In Chinese cabbage, DSEs inoculation caused higher Cs accumulation in above ground plant parts, whereas in tomato, Cs accumulation decreased significantly with three of the isolates tested, i.e., V. simplex Y34, P. ibarakiensis I.4-2-1, and the as yet unidentified taxon 312-6 suggesting low-risk transfer on the above ground plants parts as a result of high and negative plant reactions rather than high and positive reactions as it is the case with Chinese cabbage. These results suggested that DSEs can be recommended for use with Chinese cabbage to enhance phytoremediation of Cs in surrounding contaminated areas. With tomato, DSEs can be recommended for decreasing the accumulation of Cs in plants under contaminated environments.