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Endophytic fungi are diverse microorganisms that colonize plants symbiotically without causing overt infections. While numerous studies have focused on endophytes in terrestrial plants, there are no prior reports of endophytes associated with algae in Iran. Samples of Ulva sp. were collected during the fall of 2022 from the Bandar Abbas Fishery Coast, Iran, and transported to the laboratory. Following surface sterilization, the samples were cultured on potato dextrose agar (PDA) medium and incubated at 25 °C for 3 weeks. The resulting isolates were purified using the hyphal tip method. This study identified 33 fungal isolates from Ulva sp. collected at the Bandar Abbas Fishery Coast, Iran. Morphological and molecular analyses classified these isolates into 7 species across 6 genera: Alternaria, Aspergillus, Chaetomium, Cladosporium, Penicillium, and Syncephalastrum. Aspergillus was the most abundant genus (34% of isolates), while Alternaria and Syncephalastrum were the least frequent (9% each). Phylogenetic analyses of ITS, β-tubulin, GAPDH, TEF, and LSU gene sequences supported the morphological identification of the isolates. Species identified included Alternaria alternate, Aspergillus caespitosus, Aspergillus terreus, Chaetomium globosum, Cladosporium cladosporioides, Penicillium digitatum, and Syncephalastrum racemosum. All species are reported here for the first time as endophytes of Ulva sp. in Iran. Furthermore, this study represents the first documentation of endophytic fungi associated with the marine alga Ulva sp. in Iranian waters. This research enhances understanding of the ecological interactions between fungal endophytes and marine algae in Iranian ecosystems, emphasizing the diversity of symbiotic relationships in aquatic environments.
Introduction
The southern coasts of Iran, bordering the Persian Gulf and the Sea of Oman, are recognized for their rich biological resources, particularly marine macroalgae (seaweeds). Seaweed communities rank among the most productive and biodiverse marine ecosystems, serving as primary producers and a significant contribution to global oxygen production. Investigating endophytic fungi associated with these macroalgae is essential to understanding the ecological dynamics and biodiversity of Iran’s coastal regions. Globally, over 6,000 seaweed species have been identified, with approximately 300 species documented in the Persian Gulf and the Sea of Oman1. The southern coasts of Iran, bordering the Persian Gulf and the Sea of Oman, exhibit remarkable biodiversity, particularly in marine macroalgae (seaweeds). Seaweed communities rank among the most productive marine ecosystems globally, with primary production rates even those from tropical regions’ rainforests2. The high productivity of multicellular seaweeds and eukaryotic organisms3 is critical to marine ecosystems. Ulva species are key elements in the stability of coastal ecosystems by playing important roles in primary production, biogeochemical cycles, and bioremediation. In addition, many Ulva species serve as food for invertebrates and fish, thereby supporting biodiversity4. Endophytic fungi, a diverse group of microorganisms, colonize plants symbiotically without causing overt harm5– 6. Over recent decades, these fungi have attracted considerable research interest due to their functional traits, including enhancing plant growth and tolerance to biotic and abiotic stresses7, 8–9. They offer promising strategies for mitigating yield losses caused by abiotic stress10 and can protect host plants from pathogens6. Additionally, endophytes produce bioactive metabolites with applications in medicine, agriculture, and industry11– 12.
Endophytic colonization has been documented across diverse plant ecosystems, from tropical rainforests to temperate herbaceous communities. However, studies on endophytic fungi associated with marine macroalgae, such as Ulva sp. (family: Ulvaceae), remain limited. The coastal regions of Bandar Abbas, Iran, host abundant Ulva populations, yet their fungal endophytes remain understudied. This study addresses this gap by investigating endophytic fungi in Ulva sp. from the Shilat-Bandar Abbas coastline. Insights from this research could advance understanding of fungal-algal symbioses and their potential applications in agriculture and ecology.
Materials and methods
Collection of plant material and isolation of endophytes
In autumn 2022, during one sampling session, thirty-eight fresh, healthy, and disease-free Ulva sp. specimens were collected from the Fishery Coast in Bandar Abbas, Iran. Samples were rinsed with seawater to remove sand and epiphytes, stored in sterile plastic bags, and transported to the mycology laboratory of the Faculty of Agriculture at Tarbiat Modares University. Samples were washed with sterile distilled water and refrigerated at 4 °C. A multi-step surface sterilization protocol was applied:
Immersion in 70% ethanol for 1 min.
Rinsing with sterile distilled water.
Immersion in 70% ethanol for 15 s.
Triple rinsing with sterile distilled water.
To validate sterilization efficacy, aliquots from the final rinse water were cultured on potato dextrose agar (PDA). The absence of fungal growth in these controls confirmed successful surface disinfection. Samples were air-dried, cut into 1 cm² fragments, and placed on three culture media:
PDA (Potato Dextrose Agar),
PDA-SW (PDA supplemented with 200 mL L⁻¹ sterilized seawater),
PDA-SLE (PDA supplemented with 200 mL L⁻¹ sterilized Ulva extract).
Petri dishes were incubated at 25 °C for 3 weeks. Emerging fungal colonies were isolated using the hyphal tip method and identified morphologically with standard taxonomic keys. Initial genus-level identification relied on macroscopic traits (colony morphology, pigmentation) and microscopic traits (spore structure, hyphal characteristics). Isolates were further cultured on Czapek’s Yeast Extract Agar (CYA), Malt Extract Agar (MEA), and Potato Carrot Agar (PCA) for detailed species-level identification. An Olympus BX51 light microscope was used to observe the morphological features of the fungal isolates.
The identification of fungal species was conducted using established taxonomic keys from authoritative sources: Alternaria alternata was identified following Simmons (2007)13, Aspergillus species identification was based on Klich (2002)14. For Chaetomium globosum, identification relied on the key by Watanabe (2002)15. Cladosporium cladosporioides was identified using the key by Bensch et al.. (2012)16. The identification of Penicillium digitatum was based on the works of Carmichael (1955)17 and Pitt and Hocking (2009)18. Finally, Syncephalastrum racemosum was identified using keys from Benjamin (1966)19, Domsch and Gams (1980)20, and Zycha et al.. (1969)21.
Molecular identification
Morphological analysis classified the isolates into six genera: Aspergillus, Penicillium, Chaetomium, Cladosporium, Alternaria, and Syncephalastrum. For molecular identification, genomic DNA was extracted from eight isolates. Fungi were cultured on PDA at 28 °C for 7 days, after which mycelia were harvested, frozen in liquid nitrogen, and disrupted using a mortar and pestle. Genomic DNA from fungi was extracted using the cetyltrimethylammonium bromide (CTAB) method, with slight modifications, following the protocol of Gardes and Bruns (1993)22.
PCR amplification
Gene targets for amplification included the ITS rDNA region, β-tubulin, TEF, LSU, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and were selected based on taxonomic requirements. To amplify the genetic regions ITS, TUB2, TEF-1α, GAPDH, and D1/D2, the following primers were utilized respectively: ITS1 5′-CTTGGTCATTTAGAGGAAGTAA-3′, ITS4 5′-TCCTCCGCTTATTGATATGC-3′23, T1 5′-AACATGCGTGAGATTGTAAGT-3′, T22 5′-TCTGGATGTTGTTGGGAATCC-3′24, EF1-728 F 5′-CATCGAGAAGTTCGAGAAGG-3′, EF1-986R 5′-TACTTGAAGGAACCCTTACC-3′25, gpd1 5′-CAACGGCTTCGGTCGCATTG-3′, gpd2 5′-GCCAAGCAGTTGGTTGTGC-3′26, D1 5′-AACTTAAGCATATCAATAAGCGGAGGA-3′, and D2 5′-GGTCCGTGTTTCAAGACGG-3′27.
PCR reactions (25 µL total volume) were prepared with the following components:
2.5 µL 10× PCR buffer,
1.5 mM MgCl2,
200 µM dNTPs,
0.1 µM forward and reverse primers,
0.04 U/µL Taq DNA polymerase (Cinagene, Iran),
10 ng template DNA.
The thermal cycling protocol for DNA amplification employing different primers is detailed in Table 1. The gene region was amplified using a SimpliAmp thermal cycler (Thermo Fisher Scientific, Waltham, Massachusetts, USA).
Table 1. Thermal cycling protocol for amplification using different primers.
Genomic region | Initial denaturation (Temperature// time) | 36 thermal cycles (Temperature//time) | Final extension (Temperature// time) | ||
|---|---|---|---|---|---|
Denaturation | Annealing | Extension | |||
ITS-rDNA | 95 °C// 1 min | 95 °C//1 min | 56 °C// 30 S | 72 °C// 1 min | 72 °C// 5 min |
β-tubulin | 94 °C// 1 min | 94 °C//30 S | 47 °C//30 S | 72 °C//150 S | 72 °C// 10 min |
LSU | 94 °C// 5 min | 94 °C// 60 S | 52 °C// 60 S | 72 °C// 120 S | 72 °C// 10 min |
EF- 1α | 94 °C// 5 min | 94 °C// 15 S | 61 °C// 30 S | 72 °C// 30 S | 72 °C// 8 min |
GAPDH | 95 °C// 5 min | 95 °C//30 S | 57 °C// 30 S | 72 °C// 1 min | 72 °C// 7 min |
Sequencing and phylogenetic analysis
PCR products were visualized via agarose gel electrophoresis under UV light. Amplicons were sequenced bidirectionally (Codon Genetics, Iran) and edited using BioEdit v7.2.5. Sequences were aligned with reference data from GenBank using MAFFT v7.4 and curated in Mesquite v3.6.
Phylogenetic trees in Fig. 1 (Aspergillus, Penicillium, and Chaetomium genera), Fig. 3 (Cladosporium), and Fig. 4 (Syncephalastrum) were constructed using the Bayesian method, while the tree in Fig. 2 (Alternaria) was constructed using maximum parsimony. All analyses were performed through the CIPRES Science Gateway, and final visualizations were prepared in Adobe Illustrator 2019.
Fig. 1 [Images not available. See PDF.]
The MrBayes phylogenetic tree was constructed for various species within the Aspergillus, Penicillium, and Chaetomium genera by integrating the ITS-rDNA region and the β-tubulin gene, utilizing the CIPRES Science Gateway. ML/PP bootstrap support values and posterior probabilities (PP) are shown at the nodes. The phylogenetic tree was rooted with Xylaria wallichii(Accession: ON222810/MZ695797) (Specimen No.: FCATAS911 (HT)). Bold font denotes the species investigated in this study.
Fig. 2 [Images not available. See PDF.]
The Maximum Parsimony (MP) phylogenetic tree for Alternaria spp. was constructed by integrating the ITS-rDNA region and the GAPDH gene, using the CIPRES Science Gateway. ML/MP bootstrap support values and posterior probabilities are shown at the nodes. The phylogenetic tree was rooted with Alternaria alternantherae strain CBS 124,392(Accession: KC584179/KC584096). Bold font denotes the species investigated in this study.
Fig. 3 [Images not available. See PDF.]
The MrBayes phylogenetic tree was constructed for various species within the Cladosporium genus by integrating the ITS-rDNA region and the TEF gene, utilizing the CIPRES Science Gateway. ML/PP bootstrap support values and posterior probabilities (PP) are shown at the nodes. The phylogenetic tree was rooted with Cercospora beticola strain CBS 116,456(Accession: NR_121315/AY840494). Bold font denotes the species investigated in this study.
Fig. 4 [Images not available. See PDF.]
The MrBayes phylogenetic tree was constructed for various species within the genus of Syncephalastrum by integrating the ITS-rDNA region and the D1/D2 gene, utilizing the CIPRES Science Gateway. ML/PP bootstrap support values and posterior probabilities are shown at the nodes. The phylogenetic tree was rooted with Rhizopus americanus strain CBS 340.62(Accession: MH869767/HM999967). Bold font denotes the species investigated in this study.
Table 2. Taxa and phyla of endophytic fungi isolated from Ulva sp. with GenBank accession numbers and gene regions used in the phylogenetic analyses.
Taxa | Phylum | GenBank Accession Numbers | Gene regions |
|---|---|---|---|
Alternaria alternata Alternaria alternata | Ascomycota | PQ614901.1 | ITS |
PQ766530.1 | GAPDH | ||
Alternaria alternata | Ascomycota | PQ614905.1 | ITS |
Alternaria alternata | PQ766531.1 | GAPDH | |
Aspergillus caespitosus | Ascomycota | PQ619416.1 | ITS |
Aspergillus caespitosus | PQ766532.1 | β-tubulin | |
Aspergillus terreus | Ascomycota | PQ588088.1 | ITS |
Aspergillus terreus | PQ766533.1 | β-tubulin | |
Chaetomium globosum | Ascomycota | PQ588476.1 | ITS |
Chaetomium globosum | PQ766535.1 | β-tubulin | |
Cladosporium cladosporioides | Ascomycota | PQ614852.1 | ITS |
Cladosporium cladosporioides | PQ766529.1 | TEF | |
Penicillium digitatum | Ascomycota | PQ619432.1 | ITS |
Penicillium digitatum | PQ766534.1 | β-tubulin | |
Syncephalastrum racemosum | Mucoromycota | PP176476.1 | ITS |
Syncephalastrum racemosum | PQ665121.1 | LSU |
Results
This study aimed to isolate and identify endophytic fungi associated with the genus Ulva in Iran. Morphological characterization identified the seaweed as Ulva sp., characterized by vivid grass-green, tubular fronds with unbranched thalli28– 29. A total of 33 fungal isolates were obtained from Ulva sp. collected at the Bandar Abbas Fishery Coast, Iran. Three different culture media were employed to isolate fungi. According to the findings and observations, the highest number of isolates was obtained from the PDA-SLE medium, which was therefore chosen as the optimal culture medium for this study. Based on cultural and morphological characteristics, all isolates were classified into 7 species across 6 genera: Alternaria, Aspergillus, Chaetomium, Cladosporium, Penicillium (Ascomycota), and Syncephalastrum (Mucoromycota) (Table 2).
Taxonomic distribution
Aspergillus (11 isolates, 34% of total),
Penicillium (7 isolates, 21%),
Chaetomium (5 isolates, 15%),
Cladosporium (4 isolates, 12%),
Alternaria (3 isolates, 9%),
Syncephalastrum (3 isolates, 9%).
Aspergillus was the most abundant genus, while Alternaria and Syncephalastrum were the least frequent.
Molecular validation
Eight isolates were selected for molecular analysis. Sequences of the ITS rDNA region, β-tubulin, TEF, LSU, and GAPDH genes were compared to GenBank databases using BLAST. Morphological identifications were confirmed for all isolates.
Species descriptions
Alternaria alternata
Morphology: Grayish-green colonies (50 mm) on PCA. Conidiophores were vertical (40–70 × 3–4 μm), with ellipsoidal conidia (24.5–35 × 5.5–9 μm).
Molecular: ITS and GAPDH sequences matched A. alternata (3 isolates).
Aspergillus caespitosus
Morphology: Colonies grew 50 mm in 7 days; green/olive conidia with light yellow reverse. Conidiophores were smooth (150–250 × 5–6 μm), with hemispherical vesicles (9–15 μm). Conidia were globose, rough-walled (3.5–4.5 μm).
Molecular: ITS and β-tubulin sequences matched A. caespitosus (1 isolate).
Aspergillus terreus
Morphology: Colonies on MEA reached 55 mm in 7 days at 25 °C, with pale orange-buff surfaces and yellow reverse. Conidial heads were dense, and double-columned; conidiophores were smooth to slightly rough (148–247 μm), with globose vesicles (14.5–20 μm). Conidia were globose (2–2.5 μm).
Molecular: ITS and β-tubulin sequences matched A. terreus (10 isolates).
Chaetomium globosum
Morphology: Olive-green colonies (8 cm) on PDA. Perithecia were spherical with club-shaped asci (45–57 × 10–12 μm) and lemon-shaped ascospores.
Molecular: ITS and β-tubulin sequences matched C. globosum (5 isolates).
Cladosporium cladosporioides
Morphology: Olive colonies (41 mm) on SNA. Conidiophores were cylindrical (27–160.5 × 2.9–4 μm), with ovoid conidia (3.5–5 × 2–3 μm).
Molecular: ITS and TEF sequences matched C. cladosporioides (4 isolates).
Penicillium digitatum
Morphology: Green colonies (41 mm) on MEA. Conidiophores were thin (62–154 × 5–6.5 μm), with cylindrical phialides and oval conidia (6.3–9.5 × 3–6 μm).
Molecular: ITS and β-tubulin sequences matched P. digitatum (7 isolates).
Syncephalastrum racemosum
Morphology: Rapid growth on PDA (white to black colonies). Sporangiophores were branched (3–4 μm), with spherical vesicles (11–16 μm) and ovoid sporangiospores (2–6 μm).
Molecular: ITS and LSU sequences matched S. racemosum (3 isolates).
In this study, phylogenetic analyses were performed using gene regions selected for their taxonomic utility in fungal classification. Phylogenetic trees for Aspergillus, Penicillium, and Chaetomium were constructed using sequences from the ITS rDNA region and β-tubulin gene (Fig. 1). For Cladosporium, the ITS region and translation elongation factor (TEF) gene were analyzed (Fig. 3). Alternaria phylogenies were resolved using the ITS region and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene (Fig. 2). Finally, Syncephalastrum was analyzed using the ITS region and large subunit (LSU) rDNA (Fig. 4).
For the phylogenetic analysis of Aspergillus, Penicillium, and Chaetomium, a dataset containing 19 ingroup taxa and the outgroup Xylaria wallichii (Accession: ON222810/MZ695797) (Specimen No.: FCATAS911 (HT)) was analyzed. The results supported the morphological identification of the isolates from the genera Aspergillus, Penicillium, and Chaetomium. Specifically, the A. terreus isolate grouped with the reference strain CBS 117.37 (Accession: FJ531206/FJ491704), and the A. caespitosus isolate clustered with strains V313-04(Accession: OR418500/OR451368) and NRRL 1929 (Accession: EF652428/EF652252) in the phylogenetic tree based on ITS and β-tubulin gene sequences. Additionally, the isolates of P. digitatum and C. globosum formed clusters with their respective reference strains CBS 112,082 (Accession: MH862889/KJ83444) and strain CBS 160.62 (Accession: MH858130/KT214742), showing strong genetic similarity and confirming the accuracy of their identification (Fig. 1).
Phylogenetic analysis of Alternaria involved selecting three isolates identified as A. alternata based on morphological features, which were analyzed using ITS and GAPDH gene sequences. A dataset comprising 14 ingroup taxa and the outgroup Alternaria alternantherae strain CBS 124,392 (Accession: KC584179/KC584096) was used. The resulting phylogenetic tree (Fig. 2) showed that two isolates of A. alternata clustered within the subclade of section Alternata and grouped with reference strains EGS 34 − 016 1 (accession: AF347031/AY278808) and strain EGS 34 − 015 (accession: AF347032/AY278809). Furthermore, the genetic variation within the Alternata section led to the formation of distinct subclades, indicating considerable genetic heterogeneity within this section.
The morphological analysis identified the four isolates as C. cladosporioides. To confirm this, a phylogenetic analysis was performed using ITS-rDNA and translation elongation factor (TEF) gene sequences. The dataset included 18 ingroup taxa and the outgroup Cercospora beticola strain CBS 116,456(Accession: NR_121315/AY840494). BLAST comparisons revealed high sequence similarity between the isolate under study and reference strains of C. cladosporioides. Phylogenetic analysis (Fig. 3) placed C. cladosporioides, the species obtained in this study, within the C. cladosporioides clade, clustering it with the reference strain CBS 112,388(Accession: HM148003/HM148244), thereby confirming the morphological observations.
BLAST analysis revealed that the ITS-rDNA and LSU sequences of the isolate identified as S. racemosum based on morphological characteristics closely matched S. racemosum reference sequences in the NCBI GenBank. To resolve species boundaries, a multigene phylogenetic analysis was performed using MrBayes, incorporating 10 ingroup taxa and the outgroup Rhizopus americanus strain CBS 340.62(Accession: MH869767/HM999967). Phylogenetic results placed the isolate from this study within the S. racemosum clade, clustering with strains CBS 302.65 (Accession: MH870214/MH858577) and CBS 441.59 (Accession: MH869451/MH857910) (Fig. 4). Morphological traits characterized by fast spore production, round vesicle structures, and oval-shaped sporangiospores further supported this identification.
Discussion
Fungi represent one of Earth’s most diverse organisms, with approximately 156,000 documented species globally (Species Fungorum, 2024). Marine fungi, despite their ecological significance in nutrient cycling and symbiotic interactions, remain understudied. This study offers the first report of endophytic fungi associated with Ulva sp. in Iran, identifying seven species across six genera (Aspergillus, Penicillium, Cladosporium, Alternaria, Chaetomium, and Syncephalastrum), thus expanding knowledge of fungal diversity in Iran’s coastal ecosystems and revealing novel host-fungus associations. Aspergillus dominated the isolates (34%), consistent with its widespread occurrence in marine algae30– 31, while Alternaria and Syncephalastrum had the lowest percentages, each at 9%.
A. caespitosus and S. racemosum were documented as endophytes of Ulva sp. for the first time globally. Although previously isolated from soil and terrestrial plants, respectively32– 33, their presence in marine algae underscores their adaptability to diverse environments. Also, the fungi A. alternata, P. digitatum, and C. cladosporioides were identified as endophytes of Ulva sp. for the first time globally. This study reports, for the first time, the isolation of C. globosum and A. terreus as endophytic fungi from the green macroalga Ulva sp. in Iran. A. alternata and A. tenuissima were recorded in Iranian waters for the first time, suggesting biogeographic variability in algal-fungal partnerships34.
Robust species delimitation was achieved through the combined morphological and multi-gene phylogenetic analyses (ITS, β-tubulin, GAPDH, TEF, LSU). For instance, A. terreus was characterized by pale orange-buff colonies and globose conidia (2–2.5 μm), confirmed by ITS/β-tubulin sequencing, while S. racemosum exhibited rapid sporulation and ovoid sporangiospores (2–6 μm), validated by LSU/ITS data. Comparisons with global studies reveal consistency with prior records of A. terreus and C. globosum as marine endophytes35– 36.
Previous studies in Iran have primarily focused on fungi associated with mangroves or fish, while endophytes in Ulva remain largely unexplored. In a recent study investigating fungal endophytes associated with algae from the southern shores of the Persian Gulf and the Sea of Oman, several species were isolated and reported. The fungi identified include A. niger, A. flavus, A. terreus, A. puniceus, A. carlsbadensis, A. egyptiacus, A. chevalieri, P. chrysogenum, Penicillium sp., C. spicifera, and C. macrocarpum. Notably, this study did not report any endophytic fungi from the genus Ulva. This highlights a substantial gap in our understanding of the diversity of endophytic fungi associated with marine algae within the Iranian ecosystem37. Globally, only a few studies have investigated Ulva endophytes, such as research conducted in Bangladesh38. The endophytic fungus Beauveria sp. has been reported to be isolated from the algae Ulva sp., specifically collected along the Mediterranean coastline39. Rigidoporus vinctus, a basidiomycete fungus, and Candida railenensis, a yeast, were identified in a study focused on the multi-functional bioactive secondary metabolites derived from endophytic fungi associated with marine algae. Specifically, these fungi were sourced from algae belonging to the genera Enteromorpha and Ulva, both of which are part of the Ulvaceae family40.In a study focused on antioxidant activities, cytotoxicity and anticancer properties of extracts of endophytic fungi isolated from algae, different species of Ulva spp. were identified. The isolated endophytic fungi included Chaetomium sp., Phomopsis sp., Acremonium sp., A. niger and Cladosporium sp.41. Ulva lactuca algae as host of fungal endophytes A. niger, A. terreus, Chatomium sp., Cladosporium sp., Eurotium sp., Leotiomyceta sp., P.chrysogenum, and Wigrospora sp. and Ulva linza algae as the host of the fungal endophyte Alternaria sp. have been reported. Additionally, fungal endophytes such as Aspergillus sp. from the algae Ulva intestinalis and Penicillium sp. from Ulva sp. have been reported42. The species S. racemosum has been isolated and identified as an endophytic fungus from the red algae Gracilaria corticata34. In a study conducted on 14 different algae species from the Bay of Fundy in Canada, researchers aimed to explore the natural compounds produced by endophytic fungi associated with macroalgae. In this study, fungal species Bionectria ochroleuca, Cordyceps sp., Penicillium sp., and Leptosphaeria sp. were identified and isolated in connection with Ulva intestinalis31. From the Ulva fasciata algae gathered along the coast of Tamil Nadu, South India, endophytic fungi have been identified, including A. niger, Curvularia species (Curvularia sp. and Curvularia lunata), Chaetomium species, Aspergillus species (Aspergillus sp. and A. terreus), and Paecilomyces species35. The fungal endophyte C. globosum has been isolated from the marine green alga Ulva pertusa from China36. The functional roles of these endophytes, such as nutrient exchange or stress tolerance, remain unexplored but deserve further study. For example, A. terreus is recognized for its production of bioactive compounds43. Endophytes support host plant growth through processes like nitrogen fixation, phosphate solubilization, and biological control of plant pathogens44. Broadening the scope of sampling to include additional Iranian coastal areas, such as the Persian Gulf and Sea of Oman, and diverse macroalgal hosts like Gracilaria and Sargassum, may reveal more extensive biogeographic patterns and co-evolutionary relationships. Additionally, endophytes like A. caespitosus may aid algal adaptation to climate change-induced stressors, such as warming oceans, a critical avenue for future research45.
This study examines fungal endophytes associated with Ulva species in a specific marine region of Iran. Given the widespread distribution of Ulva species along both the southern and northern coasts of Iran, this research could serve as an important step toward expanding future studies and enhancing our understanding of the ecological interactions between fungal endophytes and seaweeds in Iranian marine ecosystems.
Conclusion
This study offers the first report of endophytic fungi in Iranian Ulva sp., revealing 7 new records and highlighting the need for integrative approaches (morphology + genomics) in mycological research.
Acknowledgements
The authors acknowledge Tarbiat Modares University, Tehran, Iran, for its financial support.
Author contributions
The research was designed, executed, and finalized through the collective efforts of Maryam Besharati-Fard, S. Ali Moosawi-Jorf, Mehdi Razzaghi-Abyaneh and Masoomeh Shams-Ghahfarokhi, who jointly contributed to conceptualization, experimentation, data analysis, and manuscript preparation.
Data availability
The datasets generated and/or analysed during the current study are available in the GenBank repository, https://www.ncbi.nlm.nih.gov/ (Table 2.).
Declarations
Competing interests
The authors declare no competing interests.
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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