Research Article |
|
Corresponding author: Saisamorn Lumyong ( scboi009@gmail.com ) Corresponding author: Kevin D. Hyde ( kdhyde3@gmail.com ) Academic editor: Malgorzata Ruszkiewicz-Michalska
© 2025 Sahar Absalan, Alireza Armand, Ruvishika S. Jayawardena, Nakarin Suwannarach, Jutamart Monkai, Nootjarin Jungkhun, Saisamorn Lumyong, Kevin D. Hyde.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Absalan S, Armand A, Jayawardena RS, Suwannarach N, Monkai J, Jungkhun N, Lumyong S, Hyde KD (2025) Endophytic xylariaceous fungi from rice in northern Thailand: discovery of novel species and new host records. MycoKeys 120: 1-34. https://doi.org/10.3897/mycokeys.120.152187
|
Rice (Oryza sativa L.) is a major economic crop and a staple food in Asian countries, especially Thailand. Various fungi, including endophytes, are associated with rice and play a significant role in its growth and health. Endophytic xylarialean species are known for their diverse potential roles; however, limited information is available about this group of fungi in relation to rice. Two new species (Microdochium oryzicola and Nemania oryzae) and three new host records (Apiospora intestini, A. mukdahanensis, and Nemania primolutea) on rice are introduced in this study. Species identification was based on morphological characteristics and phylogenetic analyses of the combined internal transcribed spacers (ITS), 28S ribosomal RNA (LSU), RNA polymerase II second largest subunit (rpb2), β-tubulin (tub2), and translation elongation factor 1-alpha (tef1-α) loci. Descriptions, illustrations, and phylogenetic analysis results of the new species and new records are provided.
fungal endophyte, new taxa, Oryza sativa, phylogeny, taxonomy, Xylariomycetidae
The term “xylariaceous taxa” refers to the members of subclass Xylariomycetidae, as introduced by
Over the past half-century, research has unveiled a remarkable diversity of xylariaceous endophytes (
Healthy tissue parts (leaves and panicles) of glutinous and jasmine rice cultivars were collected from Chiang Rai Province, Thailand, from November to December 2021. Samples enclosed in plastic bags were transported to the laboratory with labels containing collection details. A surface sterilization method (
Two hundred milligrams of two-week-old mycelia were used to extract genomic DNA following the protocols of the OMEGA E.Z.N.A.® Forensic DNA Kit. Five loci, including internal transcribed spacers (ITS), 28S large subunit ribosomal RNA (LSU), RNA polymerase II second largest subunit (rpb2), β-tubulin (tub2), and translation elongation factor 1-alpha (tef1-α), were amplified by polymerase chain reaction (PCR) using appropriate primers. The PCR thermal cycle program and primers used in this study are listed in Table
| Locus | Primers | PCR conditions | References |
|---|---|---|---|
| ITS | ITS5/ITS4 | 94 °C 3 min; 35 cycles of 94 °C 45 s, 56 °C 1 min, 72 °C 1 min; 72 °C 10 min |
|
| LSU | LROR/LR5 | 94 °C 3 min; 35 cycles of 94 °C 30 s, 55 °C 50 s, 72 °C 90 s; 72 °C 10 min |
|
| tef1-α | EF-1/EF-2 | 94 °C 90 s; 35 cycles of 94 °C 45 s, 55 °C 45 s, 72 °C 1 min; 72 °C 10 min |
|
| tub2 | T1/Bt2b | 94 °C 3 min; 35 cycles of 94 °C 30 s, 56 °C 30 s, 72 °C 1 min; 72 °C 10 min |
|
| rpb2 | RPB2–5F2/RPB2–7cR | 94 °C 90 s; 40 cycles of 94 °C 30 s, 55 °C 30 s, 72 °C 2 min; 72 °C 10 min |
|
Phylogenetic analyses were conducted following the methods outlined in
The combined alignment underwent Maximum Likelihood (ML) analysis using RAxML-HPC2 on XSEDE (version 8.2.8) (
From 24 samples collected across five districts, eight fungal isolates were recovered, all classified within the Xylariomycetidae. Micro-morphological characteristics and phylogenetic analyses led to the discovery of two new species (Microdochium oryzicola and Nemania oryzae) and the identification of three new host records (Table
| Species | Strain number | Plant tissue part | Location | Cultivar |
|---|---|---|---|---|
| Apiospora intestini |
|
leaf | Mueang Phan Sub-district, Phan District, Chiang Rai Province | RD15 |
| Apiospora mukdahanensis |
|
panicle | Huai Sak Sub-district, Mueang Chiang Rai District, Chiang Rai Province | RD15 |
| Daldinia eschscholtzii |
|
panicle | Mueang Phan Sub-district, Phan District, Chiang Rai Province | RD6 |
|
|
panicle | Thung Ko sub-district, Wiang Chiang Rung District, Chiang Rai Province | Nan59 | |
|
|
panicle | San Sai Ngam Sub-district, Thoeng District, Chiang Rai Province | SPT1 | |
| Microdochium oryzicola |
|
leaf | Doi Luang District, Chiang Rai Province | CP 888 |
| Nemania primolutea |
|
panicle | San Sai Ngam Sub-district, Thoeng District, Chiang Rai Province | SPT1 |
| Nemania oryzae |
|
panicle | Mueang Phan Sub-district, Phan District, Chiang Rai Province | RD6 |
The phylogram of Daldinia, including 46 strains, was generated from ML analysis based on concatenated four-locus (ITS, LSU, rpb2, tub2) sequence data, which comprised 3,942 characters after alignment. The best-scoring RAxML tree, with a final ML optimization likelihood value of –18009.449198, is presented. The matrix contained 1,258 distinct alignment patterns, with 46% of undetermined characters or gaps. Estimated base frequencies were as follows: A = 0.238507, C = 0.256708, G = 0.258390, T = 0.246395; substitution rates were AC = 1.331536, AG = 4.448940, AT = 1.375914, CG = 1.061357, CT = 7.325168, GT = 1.000000. The gamma distribution shape parameter alpha was 0.195267. The Bayesian tree converged at the 1,000,000th generation with an average standard deviation of split frequencies of 0.052336.
The phylogram of Nemania, including 43 strains, was generated from ML analysis based on concatenated four-locus (ITS, LSU, rpb2, tub2) sequence data, which comprised 2,456 characters after alignment. The best-scoring RAxML tree, with a final ML optimization likelihood value of –19593.464797, is presented. The matrix contained 984 distinct alignment patterns, with 24.01% of undetermined characters or gaps. Estimated base frequencies were as follows: A = 0.252794, C = 0.252919, G = 0.262664, T = 0.231622; substitution rates were AC = 1.337793, AG = 5.997557, AT = 1.050824, CG = 1.258166, CT = 8.646548, and GT = 1.000000. The gamma distribution shape parameter alpha was 0.199517. The Bayesian tree converged at the 1,000,000th generation with an average standard deviation of split frequencies of 0.025689.
The phylogram of Microdochiaceae, including 72 strains, was generated from ML analysis based on concatenated three-locus (ITS, LSU, rpb2) sequence data, which comprised 2,048 characters after alignment. The best-scoring RAxML tree, with a final ML optimization likelihood value of –15255.408941, is presented. The matrix contained 689 distinct alignment patterns, with 14.02% of undetermined characters or gaps. Estimated base frequencies were as follows: A = 0.262262, C = 0.228560, G = 0.263931, and T = 0.245247; substitution rates were AC = 1.072625, AG = 4.845426, AT = 1.419528, CG = 0.964509, CT = 7.796411, and GT = 1.000000. The gamma distribution shape parameter alpha was 0.149445. The Bayesian tree converged at the 1,000,000th generation with an average standard deviation of split frequencies of 0.017893.
The phylogram of Apiospora, including 153 strains, was generated from ML analysis based on concatenated three-locus (ITS, tef1-α, tub2) sequence data, which comprised 1,343 characters after alignment. The best-scoring RAxML tree, with a final ML optimization likelihood value of –18735.939045, is presented. The matrix contained 828 distinct alignment patterns, with 19.41% of undetermined characters or gaps. Estimated base frequencies were as follows: A = 0.226457, C = 0.276708, G = 0.229953, and T = 0.266881; substitution rates were AC = 1.277370, AG = 3.702079, AT = 1.247535, CG = 1.072981, CT = 4.623924, and GT = 1.000000. The gamma distribution shape parameter alpha was 0.342877. The Bayesian tree converged at the 1,000,000th generation with an average standard deviation of split frequencies of 0.026022.
Apiospora, with the type species A. montagnei, was introduced by
Endophytic from healthy leaf of Oryza sativa. Sexual morph: not observed. Asexual morph: Hyphae 4–5.5 μm wide, septate, thick-walled, hyaline to brown. Conidiophores, conidiogenous cells, and conidia not observed.
Colonies on PDA reaching 86–90 mm in diameter after 7 days at 28 °C, white, medium dense with some immersed dark brown mycelia, cottony; reverse white.
Thailand • Chiang Rai Province, Phan District, Mueang Phan Subdistrict, from healthy tissue part of rice leaf, 5 January 2022, Sahar Absalan (NS50-1a = MFLU 25-0029) (living culture
Apiospora intestini was introduced by
Phylogram of ML analysis based on combined ITS, tef1-α, and tub2 sequence data. ML bootstrap support values equal to or higher than 60% and Bayesian probability values (PP) equal to or above 0.80 are given at the nodes (ML/PP). The tree is rooted to Nigrospora gorlenkoana (CBS 480.73) and N. camelliae-sinensis (CGMCC 3.18125). The isolate from the current study is highlighted in red, and type strains are indicated in bold black.
Endophytic from healthy panicle of Oryza sativa. Sexual morph: not observed. Asexual morph: Conidiophores 2.5–4 μm wide, basauxic, cylindrical, septate, straight or flexuous, sometimes reduced to conidiogenous cells, hyaline. Conidiogenous cells 7–21.5 × 4.5–6 μm (x̄ = 13 × 5 µm, n = 10), cylindrical to subcylindrical, lageniform or ampulliform, pale brown to hyaline. Conidia 5–7 × 4–5.5 μm (x̄ = 6.5 × 5 µm, n = 25), globose to subglobose, lenticular to side view with a pale longitudinal germ slit, thick-walled, brown to dark brown.
Colonies on PDA reaching 46–48 mm in diameter after 7 days at 28 °C, white, becoming pale orange with age, circular, floccose to cottony; reverse dull white.
Thailand • Chiang Rai Province, Mueang Chiang Rai District, Huai Sak Subdistrict, from healthy tissue part of rice panicle, 17 December 2021, Sahar Absalan (HS88-2b = MFLU 25-0030) (living culture
Based on the morphological and molecular data, the isolate
Daldinia was introduced by
Endophytic from healthy panicle of Oryza sativa. Sexual morph: not observed. Asexual morph: hyphomycetous. Conidiophores 1–2.3 × 0.9–1.7 µm (x̄ = 2 × 1.4 µm, n = 10), mononematous, dichotomously or trichotomously branched, with Nodulisporium-like branching pattern, bearing 1–3 conidiogenous cells from each whorl, hyaline. Conidiogenous cells 2.6–4 × 1.5–4 µm (x̄ = 3.5 × 2 µm, n = 10), holoblastic, terminal or intercalary, cylindrical, with rounded apices, hyaline. Conidia 3–5.8 × 2.6–4.2 µm (x̄ = 4 × 3.3 µm, n = 30), smooth, obovoid to ellipsoid, aseptate, mostly with flat base, hyaline.
Daldinia eschscholtzii (
Colonies on PDA reaching 63–65 mm in diameter after 7 days at 27 °C, initially white with a diffuse margin. Becoming grayish olive green with dull green patches; reverse black at the center and whitish gray at the periphery.
Thailand • Chiang Rai Province, Phan District, from healthy tissue of rice panicle, 25 October 2021, Nootjarin Jungkhun (NS11-1a = MFLU 25-0025); (living culture
Based on the morphological and molecular data, all three strains (
Phylogram of ML analysis based on combined ITS, LSU, rpb2, and tub2 sequence data. ML bootstrap support values equal to or higher than 60% and Bayesian probability values (PP) equal to or above 0.90 are given at the nodes (ML/PP). The tree is rooted to Hypoxylon fragiforme (CBS 113049) and H. griseobrunneum (CBS 331.73). The isolates from the current study are highlighted in red, and type strains are indicated in bold black.
Microdochium was introduced by
MFLU 25-0028
Endophytic from healthy leaf of Oryza sativa. Sexual morph: not observed. Asexual morph: hyphomycetous. Mycelium 2.5–4.5 μm wide, mostly superficial, branched, septate, smooth, hyaline. Conidiophores 22–63 × 2–4.5 µm (x̄ = 37 × 3.5 µm, n = 10), usually reduced to conidiogenous cells, mono- or bi-verticillate, branched, smooth-walled, hyaline. Conidiogenous cells 6–24 × 2–5 µm (x̄ = 15 × 3 µm, n = 20), cylindrical, lageniform to ampulliform, terminal or intercalary, mono- or polyblastic, hyaline. Conidia 6–16 × 2.5–4 µm (x̄ = 8.5 × 3.3 µm, n = 30), solitary, aseptate, cylindrical to clavate, obovoid, guttulate, hyaline. Chlamydospores abundant, globose to subglobose, sometimes irregular, in chains, thick-walled, pale brown to brown.
Colonies on PDA reaching 65–67 mm in diameter after 7 days at 28 °C, dark olivaceous grey in the center and white to the periphery, circular, fluffy aerial mycelium; reverse buff with olivaceous grey in the center.
Thailand • Chiang Rai Province, Doi Luang District, from healthy tissue part of rice leaf, 7 February 2022, Nootjarin Jungkhun, (NS62-1 = MFLU 25-0028); (living culture
Phylogenetic analysis of combined ITS, LSU, and rpb2 sequences revealed that our strain (
Phylogram of ML analysis based on combined ITS, LSU, and rpb2 sequence data. ML bootstrap support values equal to or higher than 60% and Bayesian probability values (PP) equal to or above 0.80 are given at the nodes (ML/PP). The tree is rooted to Zygosporium pseudomasonii (CBS 146059) and Z. mycophilum (CBS 894.69). The isolate from the current study is highlighted in red, and type strains are indicated in bold black.
Nemania was established by
Endophytic from healthy panicle of Oryza sativa. Sexual morph: Not observed. Asexual morph: Hyphomycetous. Conidiophores 1.5–4 µm wide, unbranched or sometimes dichotomously branched, smooth-walled, pale brown to hyaline. Conidiogenous cells 1.5–2.5 µm wide, cylindrical, geniculate, proliferating unclearly, smooth-walled, hyaline. Conidia 2.4–4.5 × 5.5–8.4 µm (x̄ = 3.5 × 6.4 µm, n = 30), ellipsoid to obovoid, smooth, hyaline.
Colonies on PDA reaching 69–73 mm in diameter after 7 days at 28 °C, white, circular, velvety, slightly raised, with crenate margins; reverse yellowish white.
Thailand • Chiang Rai Province, Thoeng District, San Sai Ngam Sub-District, from healthy tissue part of rice panicle, 9 November 2021, Nootjarin Jungkhun (NS39-1a = MFLU 25-0026) (living culture
The holotype strain of Nemania primolutea (HAST 91102001) was isolated from a dead trunk of Artocarpus communis (
Phylogram of ML analysis based on combined ITS, LSU, rpb2, and tub2 sequence data. ML bootstrap support values equal to or higher than 60% and Bayesian probability values (PP) equal to or above 0.80 are given at the nodes (ML/PP). The tree is rooted to Rosellinia britannica (MFLU 17-302). The isolate from the current study is highlighted in red, and type strains are indicated in bold black.
Oryzae refers to the host genus Oryza from which it was isolated.
Endophytic from healthy panicle of Oryza sativa. Sexual morph: Not observed. Asexual morph: Hyphomycetous. Hyphae 1.5–2.5 µm wide, straight, branched, septate, hyaline. Conidiophores 3–3.5 µm wide, unbranched, septate, occasionally enlarged towards the upper part, pale brown to hyaline. Conidiogenous cells 2.5–3.5 µm wide, cylindrical, pale brown to hyaline. Conidia 4.5–7 × 3–4 µm (x̄ = 6 × 3.5 µm, n = 20), obovoid, smooth, hyaline. Chlamydospores scarce, thick-walled, hyaline, globose to ellipsoidal.
Colonies on PDA reaching 65–68 mm in diameter after 7 days at 28 °C, cotton white, circular, medium dense, velvety to felty, with undulate margins; reverse white.
Thailand • Chiang Rai Province, Phan District, from healthy tissue part of the rice panicle, 9 November 2021, Nootjarin Jungkhun (NS24-1a = MFLU 25-0027) (ex-type, living culture
Nemania oryzae is proposed here as a new species based on multi-gene phylogenetic analyses. Our strain (
Rice is a vital food source, providing both protein and energy to more than half of the global population (
In the present study, eight endophytic xylariaceous strains were isolated from rice plants in northern Thailand. Identification was based on phylogenetic analyses in combination with morphological observation. However, morphological identification of endophytic xylariaceous fungi is often difficult due to their sterility or the limited diagnostic features of asexual morphs produced on standard media (
Endophytic species of Nemania have been reported from various hosts, including Asparagopsis taxiformis (red alga), Torreya taxifolia (Florida torreya), Aquilaria sinensis (incense tree), Taxus baccata (Iranian yew), and Vitis spp. (grapevine), and are recognized for their production of bioactive compounds (
Species of Apiospora are cosmopolitan (
Although xylariaceous endophytes have been recorded from various host plants in many countries, including Thailand, their association with rice has been relatively overlooked. Given the ecological and biotechnological importance of this fungal group, future studies should continue to explore xylariaceous diversity in rice to uncover novel species, their ecological roles, and potential applications in agriculture, biotechnology, and medicine. In particular, investigating the functions of beneficial endophytic fungi could contribute to sustainable agricultural practices, including soil health improvement and enhanced crop productivity, while minimizing environmental impact.
Sahar Absalan is grateful for the Chiang Mai University Presidential Scholarship. The authors thank Shaun Pennycook for assistance in correcting Latin names for the newly described taxa. This research was partially supported by Chiang Mai University, Thailand.
The authors have declared that no competing interests exist.
No ethical statement was reported.
No use of AI was reported.
This research was supported by the National Research Council of Thailand (NRCT) under grant numbers N42A650198 and NRCT-TRG010.
Conceptualization: SA, RSJ, SL. Methodology: SA, AA, NJ. Software: SA. Formal analysis: SA, AA. Writing – original draft preparation: SA. Writing – review and editing: AA, NS, JM, NJ, RSJ, KDH, SL. Supervision: SL, RSJ, KDH. Validation: AA, NS, JM, NJ, RSJ, KDH, SL. Funding acquisition: SL, RSJ. All authors have read and agreed to the published version of the manuscript.
Sahar Absalan https://orcid.org/0000-0002-6052-5381
Alireza Armand https://orcid.org/0000-0003-2455-3796
Ruvishika S. Jayawardena https://orcid.org/0000-0001-7702-4885
Nakarin Suwannarach https://orcid.org/0000-0002-2653-1913
Saisamorn Lumyong https://orcid.org/0000-0002-6485-414X
Kevin D. Hyde https://orcid.org/0000-0002-2191-0762
All of the data that support the findings of this study are available in the main text.