Nigrospora Species Associated with Various Hosts from Shandong Peninsula, China

Identification and Characterization of Nigrospora Species and a Novel Species, Nigrospora anhuiensis, Causing Black Leaf Spot on Rice and Wild Rice in the Anhui Province of China

Rice production in the Anhui province is threatened by fungal diseases. We obtained twenty-five fungal isolates from rice and wild rice leaves showing leaf spot disease collected along the Yangtze River. A phylogenetic analysis based on internal transcribed spacer (ITS), translation elongation factor 1 alpha (TEF1-α), and beta tubulin (TUB2) sequences revealed one isolate (SS-2-JB-1B) grouped with Nigrospora sphaerica, one (QY) with Nigrospora chinensis, twenty-two with Nigrospora oryzae, and one isolate (QY-2) grouped in its own clade, which are related to but clearly different from N. oryzae. Nineteen tested isolates, including sixteen strains from the N. oryzae clade and the three isolates of the other three clades, caused disease on detached rice leaves. The three isolates that did not belong to N. oryzae were also able to cause disease in rice seedlings, suggesting that they were rice pathogens. Isolate QY-2 differed from the other isolates in terms of colony morphology, cell size, and susceptibility to fungicides, indicating that this isolate represents a new species that we named Nigrospora anhuiensis. Our analysis showed that N. sphaerica, N. chinensis, and the new species, N. anhuiensis, can cause rice leaf spot disease in the field. This research provides new knowledge for understanding rice leaf spot disease.

Wildfires Increase Concentrations of Hazardous Air Pollutants in Downwind Communities

Due in part to climate change, wildfire activity is increasing, with the potential for greater public health impact from smoke in downwind communities. Studies examining the health effects of wildfire smoke have focused primarily on fine particulate matter (PM2.5), but there is a need to better characterize other constituents, such as hazardous air pollutants (HAPs). HAPs are chemicals known or suspected to cause cancer or other serious health effects that are regulated by the United States (US) Environmental Protection Agency. Here, we analyzed concentrations of 21 HAPs in wildfire smoke from 2006 to 2020 at 309 monitors across the western US. Additionally, we examined HAP concentrations measured in a major population center (San Jose, CA) affected by multiple fires from 2017 to 2020. We found that concentrations of select HAPs, namely acetaldehyde, acrolein, chloroform, formaldehyde, manganese, and tetrachloroethylene, were all significantly elevated on smoke-impacted versus nonsmoke days (P < 0.05). The largest median increase on smoke-impacted days was observed for formaldehyde, 1.3 μg/m3 (43%) higher than that on nonsmoke days. Acetaldehyde increased 0.73 μg/m3 (36%), and acrolein increased 0.14 μg/m3 (34%). By better characterizing these chemicals in wildfire smoke, we anticipate that this research will aid efforts to reduce exposures in downwind communities.

Agrobacterium tumefaciens-mediated transformation of Nigrospora sp. isolated from switchgrass leaves and antagonistic toward plant pathogens

Nigrospora is a diverse genus of fungi colonizing plants through endophytic, pathogenic, or saprobic interactions. Endophytic isolates can improve growth and development of host plants, as well as their resistance to microbial pathogens, but exactly how they do so remains poorly understood. Developing a reliable transformation method is crucial to investigate these mechanisms, in particular to identify pivotal genes for specific functions that correlate with specific traits. In this study, we identified eight isolates of Nigrospora sp. internally colonizing the leaves of switchgrass plants cultivated in North Carolina. Using an Agrobacterium tumefaciens-mediated transformation approach with control and GFP-expressing vectors, we report the first successful transformation of two Nigrospora isolates. Finally, we demonstrate that wild-type and transgenic isolates both negatively impact the growth of two plant pathogens in co-culture conditions, Bipolaris maydis and Parastagonospora nodorum, responsible for the Southern Leaf Blight and Septoria Nodorum Blotch diseases, respectively. The GFP-transformed strains developed here can therefore serve as accurate reporters of spatial interactions in future studies of Nigrospora and pathogens in the plant. Finally, the transformation method we describe lays the foundation for further genetic research on the Nigrospora genus to expand our mechanistic understanding of plant-endophyte interactions.

Alternaria arborescens and A. italica Causing Leaf Blotch on Celtis julianae in China

Celtis julianae Schneid. is widely planted as a versatile tree species with ecological and economic significance. In September 2022, a leaf blotch disease of C. julianae was observed in Nanjing, Jiangsu, China, with an infection incidence of 63%. The disease led to severe early defoliation, significantly affecting the ornamental and ecological value of the host tree. The accurate identification of pathogens is imperative to conducting further research and advancing disease control. Koch's postulates confirmed that the fungal isolates (B1-B9) were pathogenic to C. julianae. The morphology of the characteristics of the pathogen matched those of Alternaria spp. The internal transcribed spacer region (ITS), large subunit (LSU) and small subunit (SSU) regions of rRNA, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), Alternaria major allergen gene (Alt a 1), RNA polymerase second largest subunit (RPB2), and portions of translation elongation factor 1-alpha (TEF1-α) genes were sequenced. Based on multi-locus phylogenetic analyses and morphology, the pathogenic fungi were identified as Alternaria arborescens and A. italica. The findings provided useful information for disease management and enhanced the understanding of Alternaria species diversity in China. This is the first report of A. arborescens and A. italica causing leaf blotch of C. julianae in China and worldwide.

Promising drought and salinity tolerance features of Nigrospora species existing as endophytes in Oryza sativa

In this study, we report the discovery of novel Nigrospora species isolated from the extensively cultivated PUSA 44 rice variety in Punjab, India. Out of the 120 isolates examined, 6.6% and 5% isolates exhibited tolerance to high salinity and drought stress. Isolates 6OSFR2e and 7OSFS3a exhibited the highest indole acetic acid and gibberellic acid production, with 268.32 ± 08.10 and 25.72 ± 0.04 µg/mL. Additionally, isolates 7OSFS3a, 6OSFR2e and 6OSFL4c had highest antioxidant potential with IC50 345.45 ± 11.66, 391.58 ± 10.66, and 474.529 ± 11.08 µg/mL. The isolates 6OSFR2e and 6OSFL4c also exhibited phosphate solubilisation with a PI of 1.06 ± 0.00 and 1.04 ± 0.02. The highest cellulase and laccase production with EI 1.24 ± 0.00 and 1.16 ± 0.00 was observed by isolates 6OSFR2e and 6OSFL4c. Promising results were observed in the case of ammonia production. The isolates belonged to the same phylum, Ascomycota and were identified as Nigrospora zimmermanii (6OSFR2e) and Nigrospora oryzae (7OSFS3a), and Nigrospora sphaerica (6OSFL4c) using morpho-taxonomic and molecular identification. The present study provides a critical insight into the characteristics of these Nigrospora species, which could be used to develop a bio-consortium for the rejuvenation of PUSA-44 cultivation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03679-9.

Occurrence of Nigrospora osmanthi Causing Leaf Blight on Water Lettuce in China

Water lettuce (Pistia stratiotes L.), is one of the emerging invasive weeds for inland water bodies in Asia and become a major problem for local water ecosystem. Biocontrol of water lettuce by mycobiota is being considered as a promising and sustainable method (Kongjornrak et al. 2019). During July 2021, a leaf blight of water lettuce was observed within about 1.5 ha in Shenxi stream (N25°66', E119°05') in Putian, Fujian, China. The disease severity was about 100% with 80% incidence, early symptoms appeared as small irregularly yellow or brown blight, severely infected leaves turned to be rot, then death and sink. Small pieces (5 × 5 mm) of symptomatic leaves were excised and surface disinfected with 75% ethanol and 0.1% HgCl2 solution, air dried and plated on potato dextrose agar (PDA). 3~5 days after incubation at 28°C, six fungal pure cultures showing similar morphology were obtained from the infected leaves. On PDA, colonies were flat, aerial mycelium grew sparsely, most of it grew inside the agar medium, it reverses white to grey to black with age. Hyphae were branched, septate, smooth and hyaline. Conidiophores mostly reduced to conidiogenous cells and setae were not observed. Conidiogenous cells were monoblastic, discrete and solitary, at first hyaline, subspherical, then turning to pale brown, ampulliform, 4.5-10 × 3.5-6 μm in size. Conidia were solitary, globose or ellipsoidal, black, smooth, some of it formed directly from the mycelia, aseptate, 8-12 μm diam (n=10). Genomic DNA was extracted from one of the representative isolate Z1. ITS1/ITS4 (Mills et al. 1992), Bt-2a/Bt-2b (Glass and Donaldson 1995) and EF1-728F/EF-2 (O'Donnell et al. 1998) primer pairs were used to amplify the isolate's internal transcribed spacer (ITS), the Beta-tubulin fragment (TUB) and the partial translation elongation factor (TEF1), respectively. The isolate's sequences were deposited in the GenBank with accession numbers of OM279539 (ITS), OM296034 (TUB) and OM296035 (TEF1). Phylogenetic analysis using maximum likelihood based on the ITS-TUB-TEF1 concatenated sequences from Nigrospora species revealed that isolate Z1 is closely clustered with N. osmanthi strain LC4487. The fungus was identified as N. osmanthi based on the morphological characteristics and molecular analyses (Hao et al. 2020; Wang et al. 2017). Pathogenicity test were performed using twenty inoculated and control plants, respectively. Conidial suspensions (107 CFU/ml) of Z1 isolate were spray-inoculated on the leaves of healthy water lettuce seedlings, while sterile distilled water was used as control. Inoculated and control plants were kept in the differential 50-liter plastic tanks and maintained in a greenhouse at room temperature (19 to 24°C) for one month. Symptoms appeared 7 days post inoculation, which was similar to what occurs in the field. No symptoms occurred on controls. Pathogen was reisolated and confirmed by morphology and molecular analysis. Koch's postulates were conducted twice. N. osmanthi is a pathogenic fungus of many crop plants, such as buckwheat (Shen et al 2021), Java tea (Ismail et al. 2022) or buffalograss (Mei et al. 2019) in Asia and particularly in China. However, to our knowledge, this is the first report of N. osmanthi causing leaf blight on water lettuce. Further studies on how to apply formulated N. osmanthi will be required so that the strain could be effectively used to control water lettuce, moreover, its environmental safety also need a rigorous experimental evaluation.

The diversity of microfungi associated with grasses in the Sporobolus indicus complex in Queensland, Australia

There are five closely related Sporobolus species, collectively known as weedy Sporobolus grasses (WSG) or the rat's tail grasses. They are fast growing, highly competitive, unpalatable weeds of pastures, roadsides and woodlands. An effective biological control agent would be a welcomed alternative to successive herbicide application and manual removal methods. This study describes the initial exploratory phase of isolating and identifying native Australian microfungi associated with WSG, prior to evaluating their efficacy as inundative biological control agents. Accurate species-level identification of plant-pathogenic microfungi associated with WSG is an essential first step in the evaluation and prioritisation of pathogenicity bioassays. Starting with more than 79 unique fungal morphotypes isolated from diseased Sporobolus grasses in Queensland, Australia, we employed multi-locus phylogenetic analyses to classify these isolates into 54 fungal taxa. These taxa belong to 22 Ascomycete families (12 orders), of which the majority fall within the Pleosporales (>24 taxa in 7 families). In the next phase of the study, the putative species identities of these taxa will allow us to prioritise those which are likely to be pathogenic based on existing literature and their known ecological roles. This study represents the first step in a systematic, high-throughput approach to finding potential plant pathogenic biological control agents.

Secondary metabolites of the genus Nigrospora from terrestrial and marine habitats: Chemical diversity and biological activity

Secondary metabolites produced by the ascomycetes have attracted wide attention from researchers. Their diverse chemical structures and rich biological activities are essential in medicine, food, and agriculture. The monophyletic Nigrospora genus belongs to the Apiosporaceae family and is a rich source of novel and diverse bioactive metabolites. It occurs as a common plant pathogen, endophyte, and saprobe distributed in many ecosystems worldwide. Researchers have focused on discovering new species and secondary metabolites in the past ten years. The host diseases caused by Nigrospora species are also investigated. This review describes 50 references from Web of Science, CNKI, Google Scholar and PubMed related to the secondary metabolites from Nigrospora. Here, a total of 231 compounds isolated from five known species and 21 unidentified species of Nigrospora from January 1991 to June 2022 are summarized. Their structures are attributed to polyketides, terpenoids, steroids, N-containing compounds, and fatty acids. Meanwhile, 77 metabolites exhibited various biological activities like cytotoxic, antifungal, antibacterial, antiviral, antioxidant, anti-inflammatory, antileukemic, antimalarial, phytotoxic, enzyme inhibitory, etc. Notably, this review presents a comprehensive literature survey focusing on the chemistry and bioactivity of secondary metabolites from Nigrospora.

Discovery of Tropolone Stipitaldehyde as a Potential Agent for Controlling Phytophthora Blight and Its Action Mechanism Research

The fermentation of endophytic Nigrospora chinensis GGY-3 resulted in the isolation of tropolone stipitaldehyde (1), which exhibited broad-spectrum inhibition activity against fungi and bacteria, especially against Phytophthora capsici, with an EC₅₀ value of 0.83 μg/mL and Xanthomonas oryzae pv. oryzicola, with a minimum inhibitory concentration value of 4.0 μg/mL. The in vitro and in vivo assays demonstrated that 1 had a significant protective effect on P. capsici. Furthermore, 1 inhibited the spore germination of P. capsici and damaged the plasma membrane structure. As observed by SEM and TEM, after exposure to 1, mycelia exhibited swelling, shrunken, branch-increasing phenomena, cell wall and membrane damage, and disordered content. Transcriptome analysis revealed that 1 might affect starch and sucrose metabolism and fatty acid biosynthesis by suppressing the expression of genes relevant to cell wall synthetases and cell membrane-associated genes. These findings indicate that 1 may be a potential agrochemical fungicide for controlling phytophthora blight.

Mycobiomes of the Ocular Surface in Bacterial Keratitis Patients

Inflammation of the cornea is known as keratitis, and bacteria, fungi, protozoans, and viruses are the etiological agents of this disease. Delayed treatment of keratitis could result in loss of vision and, under certain severity conditions, the removal of an eye and its associated structures. In the current study, the ocular surface (conjunctiva and cornea) mycobiomes of individuals with bacterial keratitis were compared with the ocular mycobiome (conjunctiva) of healthy individuals, free of any ocular morbidity. Mycobiomes were generated through NGS approach using conjunctival swabs and corneal scrapings as the source of DNA from which ITS2 was amplified and sequenced, as a proxy to identify fungi. The results indicated significant changes in the alpha-diversity indices and in the abundance at the phylum and genera level. Hierarchical clustering using a heatmap showed that the mycobiomes were different. Furthermore, NMDS plots also differentiated the mycobiomes in the three cohorts, implying dysbiosis in the mycobiomes of the conjunctivae and corneal scrapings of bacterial keratitis individuals compared to control individuals. A preponderance of negative interactions in the hub genera in the conjunctival swabs of bacterial keratitis individuals compared to healthy controls further re-emphasized the differences in the mycobiomes. The dysbiotic changes at the genera level in conjunctivae and corneal scrapings of bacterial keratitis individuals are discussed with respect to their possible role in causing or exacerbating ocular surface inflammation. These results demonstrate dysbiosis in the ocular mycobiome in bacterial keratitis patients compared to healthy controls for the first time.

Natural Plant Extracts and Microbial Antagonists to Control Fungal Pathogens and Improve the Productivity of Zucchini (Cucurbita pepo L.) In Vitro and in Greenhouse

Background: Natural plant extracts and microbial antagonists have the potential for use in increasing the fungal resistance and productivity of horticulture plants. Methods: The purpose of this study was to evaluate the ability of both natural plant extracts and microbial antagonists as a biotical control of some fungal pathogens, i.e., Fusarium ssp., Exserohilum ssp. and Nigrospora ssp., along with improving the growth and productivity performance of zucchini under greenhouse conditions. Eucalyptus camaldulensis leaf extract (LE), Citrus sinensis LE, Ficus benghalensis fruit extract (FE), and two microbial antagonists Pseudomonas fluorescens (accession no. MW647093) and Trichoderma viride (accession no. MW647090) were tested under in vitro and in vivo conditions. Through morphological characteristics and the internal transcribed spacer (ITS) region, Fusarium solani (accession no. MW947256), F. oxysporum (accession no. MW947254), Exserohilum rostratum (accession no. MW947255), and Nigrospora lacticolonia (accession no. MW947253) were identified. HPLC analysis was used for the identification of phenolic compounds (PCs) and flavonoid compounds (FCs) in the extracts. Results: The highest inhibition percentage of fungal growth (IPFG) against F. oxysporum was obtained with P. fluorescens, T. viride, and E. camaldulensis LE (4000 mg/L); F. solani with P. fluorescens, T. viride, and C. sinensis LE (4000 mg/L); Exserohilum rostratum with P. fluorescens, Ficus benghalensis FE (4000 mg/L) and E. camaldulensis LE (4000 mg/L), and N. lacticolonia with P. fluorescens. Using HPLC analysis, the abundant PCs in E. camaldulensis LE were pyrogallol, and caffeic acid, those in C. sinensis LE were syringic acid and ferulic acid, and those in F. benghalensis FE were gallic acid and syringic acid. In addition, the abundant FCs in E. camaldulensis LE were kaempferol, and naringin, those in C. sinensis LE were hesperidin and quercetin, and those in F. benghalensis FE were kaempferol and quercetin. Under greenhouse experiments, T. viride and E. camaldulensis LE (4000 mg/L) followed by P. fluorescens + T. viride treatments gave the best results of zucchini plants in terms of leaf area, fruits number per plant, yield per plant, and total yield (marketable and non-marketable). Conclusions: Plant extracts and bioagents can be used to control some zucchini fungal pathogens and increase the productivity performance of zucchini plants.

Antimicrobial properties of marine fungi from sponges and brown algae of Mauritius

Purpose of the study: Marine fungi of Mauritius have been poorly studied. There are numerous reports on the bioactive secondary metabolites that are produced by fungi around the world. Yet, research on the molecular characterisation and the pharmaceutical potential of marine fungi in Mauritius is rather scanty. Method: The samples, which consisted of three sponges Haliclona sp., Iotrochota sp. and Biemna sp. and two brown algae Turbinaria conoides and Sargassum portierianum, were collected in the North of Mauritius during winter. No sporulating structures were observed from the fungal cultures making morphological analysis impossible. The molecular characterisation of the selected isolates was carried out by the amplification of the ITS regions and phylogenetic analysis. The antimicrobial properties were then determined using the disc diffusion and the minimum inhibitory concentration (MIC) assay. Results: Genus level identification was made from molecular data and for some isolates, species-level identification was even possible. Twelve fungi that showed the best antimicrobial properties were identified as Peniophora sp., Aspergillus cristatus, Acremonium sp., Cordyceps memorabilis, Aspergillus ochraceus, Biscogniauxia sp., Aspergillus keratitidis, Exserohilum rostratum, Chromocleista sp., Nigrospora oryzae, Aspergillus flavipes and Mycosphaerella. The lowest MIC result of 0.0098 mg/mL was obtained with Chromocleista sp. mycelium extract against Staphylococcus aureus. The MIC of the mycelium extracts was lower than the broth extracts for most isolates indicating that the antimicrobial compounds are not secreted. Conclusion: Marine fungi from the Mauritian waters have immense potential in the search for natural products against antibiotic-resistant bacteria.

Fungi in PAH-contaminated marine sediments: Cultivable diversity and tolerance capacity towards PAH

The cultivable fungal diversity from PAH-contaminated sediments was examined for the tolerance to polycyclic aromatic hydrocarbon (PAH). The 85 fungal strains, isolated in non-selective media, revealed a large diversity by ribosomal internal transcribed spacer (ITS) sequencing, even including possible new species. Most strains (64%) exhibited PAH-tolerance, indicating that sediments retain diverse cultivable PAH-tolerant fungi. The PAH-tolerance was linked neither to a specific taxon nor to the peroxidase genes (LiP, MnP and Lac). Examining the PAH-removal (degradation and/or sorption), Alternaria destruens F10.81 showed the best capacity with above 80% removal for phenanthrene, pyrene and fluoranthene, and around 65% for benzo[a]pyrene. A. destruens F10.81 internalized pyrene homogenously into the hyphae that contrasted with Fusarium pseudoygamai F5.76 in which PAH-vacuoles were observed but PAH removal was below 20%. Thus, our study paves the way for the exploitation of fungi in remediation strategies to mitigate the effect of PAH in coastal marine sediments.

Nigrospora oryzae Causing Black Leaf Spot Disease of Hibiscus mutabilis in China

Cotton rose (Hibiscus mutabilis Linn.) is a deciduous shrub native to China. It has been widely cultivated in many provinces in China for its ornamental and ecological value (Shang et al., 2020). In May 2017, an unknown leaf spot symptom was first observed on H. mutabilis at the Chengdu Campus of Sichuan Agricultural University (30°42'31″ N, 103°51'28″ E). The disease occurred from May to September with approximately 81% incidence by field sample survey of 300 plants in Chengdu Greenway. The symptoms at first appeared as irregular black spots on the leaves. Then the lesions grew and coalesced into large, black necrotic areas, which later produced leaf chlorosis and abscission (Fig. 1-A). This disease seriously reduced the ornamental value of H. mutabilis. Forty diseased lesions (4 × 5 mm) were surface sterilized with 75% alcohol for 60 s and 3% NaClO for 45 s, rinsed three times in sterile water, placed onto potato dextrose agar (PDA), and then incubated in a dark at 25°C. From the 7 obtained isolates, 4 isolates exhibited the morphology described as Nigrospora oryzae (Hao et al., 2020). The fungus produced initially circular white colonies, and then the centers turned dark gray or black with age on the PDA. Hyphae were smooth, branched, septate, hyaline, or pale brown. Conidia (N = 100 spores) were abundant, and were solitary, dark-brown to black, smooth, aseptate, and measured 11 to 15 μm in diameter (Fig. 1). DNA was extracted from the fungal colonies using a DNeasyTM Plant Mini Kit (Qiagen). The internally transcribed spacer (ITS), β-tubulin gene (TUB), and translation elongation factor 1-alpha (TEF1) were amplified with primers ITS1/ITS4 (White et al., 1990), BT2A/BT2B (Glass and Donaldson 1995), and EF1-728F/EF1-986R (O'Donnell et al., 1998; Carbone and Kohn 1999), respectively. BLAST results indicated that the ITS, TUB, and TEF1 sequences (GenBank accession Nos. MN515070, MN733956, and MN635723, respectively) had 99% identity with N. oryzae sequences (GenBank accession Nos. KX986031, KY019553, and KY019358). The result was confirmed by multilocus phylogenetic analysis (Fig. 2). The morphological characteristics and molecular analyses of the isolate matched the description of N. oryzae. To confirm pathogenicity, Koch's postulates were fulfilled under controlle conditions. The seedlings of 20 two-year-old potted H. mutabilis plants were inoculated by spraying conidial suspension at the concentration of 1 × 106 conidia/ml on both sides of leaves. Sterilized distilled water (20 seedlings) were used as negative controls. The experiment was performed three times. All plants were incubated at 25°C ± 2°C under a 16 h/8 h photoperiod and 70%-75% relative humidity (RH) after inoculation, and observed daily for disease development. Two weeks later, the inoculated plants showed the same symptoms as the original diseased plants and the controls remained asymptomatic. The pathogen N. oryzae was re-isolated from all ioculated plants, and the culture and fungus characteristics were the same as those of the original isolate. But N. oryzae was not isolated from the control plants. The results indicated that N. oryzae is a causal agent of the disease. N. oryzae was reported as a leaf pathogen on cotton (Zhang et al., 2012), but this is the first report of N. oryzae causing leaf black spot on H. mutabilis in the world. The identification could provide relevant information for adopting appropriate management strategies to control the disease.

Dark Septate Endophytic Fungi Associated with Sugarcane Plants Cultivated in São Paulo, Brazil

Dark septate endophytes (DSEs) constitute a polyphyletic group within the Ascomycota, with global distribution and a wide range of host plant species. The present study evaluated the diversity of DSE in sugarcane roots of the varieties RB867515, RB966928, and RB92579, and four varieties of not commercialized energy cane. A total of 16 DSE strains were isolated, mostly from the varieties RB966928 and RB867515, with six and five isolates, respectively. Just one of the four energy cane varieties had fungi with DSE appearance. The analyses of the DNA sequences from the internal transcribed spacer (ITS) and the large subunit (LSU), in association with the micromorphology of the isolates, allowed the differentiation of the 16 isolates in at least five species, within the families Periconiaceae, Pleosporaceae, Lentitheciaceae, Vibrisseaceae, and Apiosporaceae and the orders Pleosporales, Helotiales, and Xylariales. The order Pleosporales represented 80% of the isolates, and the species Periconia macrospinosa, with six isolates, accounted for the highest isolation frequency. The results confirm the natural occurrence of the DSE symbiosis in sugarcane varieties and the generalist character of these fungi as some of the detected species have already been reported associated with other host plants, ecosystems, and regions of the world.