Schizophyllum radiatum Fries (1851:41)

Dasanthi, Naduni, Thambugala, Kasun M., Karunarathna, Samantha C., Ediriweera, Aseni, Munasinghe, Helani, Elgorban, Abdallah M., Harischandra, Hiruni & Dharmasena, Buddhika P., 2024, Morphological and molecular insights into the hidden edible mushroom diversity in Sri Lanka, Phytotaxa 645 (3), pp. 192-213 : 200

Schizophyllum radiatum Fries (1851:41)

Index Fungorum: 18512

Figure 7 and Figure 8

Basidiocarp small. Pileus 15–30 mm wide and 30–45 mm long, flabelliform, semicircular, occasionally sessile or semistipitate, margin smooth, ragged, tightly rolled toward the hymenium, pellicle 60–70 μm thick; grey (3D1), grayish white (4C1), or white (4A1) with zones of brownish gray (5C2), brownish orange (7C3), or greyish orange (6B3); context of 100 to 300 μm thick. Hymenium formed of split gills, 430–750 μm in length; light brown (6D5) to agate (7E8), abhymenial hair simple, 3–4 μm diameter, hyaline, smooth, and slightly wavy near the apex, spores 4.1–6 × 1.8–3 μm, hyaline, cylindrical, obliquely apiculate, basidia 17–20 × 2.8–3.6 μm, claviform to narrow claviform.

Ecology and distribution:— It grows on decaying tree trunks and caespitose. This species is distributed in China, Cuba, Ecuador, India, Jamaica, Mexico, Panama, Sri Lanka (this study), and the USA.

Material examined:— Sri Lanka. Sabaragamuwa Province: Rathnapura District, Balangoda , 80°45’36.84”E 6°40’57.36”N, 7 th August 2022, Naduni Dasanthi, GenBank accession number: OR139840 , Specimen number: RH28 (USJ-H-016) .

Phylogenetic analyses of Schizophyllum

Eighteen sequences of Schizophyllum retrieved from GenBank were used for the current phylogenetic analysis. Porodisculus pendulus was used as the outgroup in phylogenetic analysis. According to the phylogenetic tree ( Figure 9 ), the ITS sequence acquired from the newly collected specimen RH28 (USJ-H-016) clustered with S. radiatum (AY571060; CBS 301.32) which is an epitype from Panama and S. radiatum (KP050645; DO90 voucher) from China in the clade C. Schizophyllum radiatum (OR139840; USJ-H-016) is a sister taxon to the subclade containing Schizophyllum sp. ( KM 386070; HL5128S voucher) and S. radiatum (KP050645; DO90 voucher) from China in clade C. However, the bootstrap value was lower than 70%, indicating poor branch support. The results of the phylogenetic tree ( Figure 9 ) raise concerns about the low bootstrap support provided by ITS rDNA for molecular separation of the strains of Schizophyllum . Additional DNA markers such as 18s rRNA and SSU can be used to obtain a phylogenetic tree with better resolution.

Notes:— Schizophyllum radiatum is recorded for the first time in Sri Lanka. Worldwide, it has been reported from Mexico, China, India, the United States, and tropical regions of the American continent such as Cuba, Jamaica, Panama, and Ecuador ( Carreño-Ruiz et al. 2019). Schizophyllum commune and S. radiatum have historically been considered conspecific due to their morphological resemblance and ITS rDNA genetic similarity. However, comprehensive multigenetic analyses substantiated that while both species share similarities and are closely related, they are distinct and independent taxa ( Siqueira et al. 2016). Schizophyllum radiatum is a commercialized edible mushroom in Tabasco and Mexico ( Carreño-Ruiz et al. 2019). Schizophyllum species have been recognized as medicinal mushrooms due to their medicinal metabolites, such as fungal polysaccharides. According to research findings, S. radiatum has been identified as a natural source of bioactive polysaccharides exhibiting anti-tumor and immunostimulant properties (LopezLegarda et al. 2021). Furthermore, investigations into S. radiatum revealed the potential of extracellular biosynthesis of silver nanoparticles, along with demonstrated antimicrobial activity and antioxidative properties ( Metuku et al. 2014). Consequently, biotechnological interest is there in exploring this species and its potential applications.

Figures

FIGURE 7. Schizophyllum radiatum (Herbarium code: USJ-H-016). a. Mature basidiomata in situ. b,c. Mature basidiomata ex-situ. Scale bars: a, b, c = 1.5 cm. Photography by Naduni Dasanthi.

FIGURE 8. Schizophyllum radiatum (Herbarium code: USJ-H-016). a. Basidiospore. b. Basidia. c. Smooth abhymenial hairs. Scale bars: a, b = 5 µm; c = 10 µm. Illustration by Aseni Ediriweera.

FIGURE 9. A phylogenetic tree for ITS sequences was constructed using maximum likelihood (ML) analysis for the genus Schizophyllum. The newly generated strain is in red. ML bootstrap values are given at the nodes. Bootstrap support values equal to or higher than 70% are provided. The tree is rooted with Porodisculus pendulus.