Abstract
Sparassis crispa (Hanabiratake) is a widely used medicinal mushroom in traditional Chinese medicine because it contains materials with pharmacological activity. Here, we report its 39.0-Mb genome, encoding 13,157 predicted genes, obtained using next-generation sequencing along with RNA-seq mapping data. A phylogenetic analysis by comparison with 25 other fungal genomes revealed that S. crispa diverged from Postia placenta, a brown-rot fungus, 94 million years ago. Several features specific to the genome were found, including the A-mating type locus with the predicted genes for HD1 and HD2 heterodomain transcription factors, the mitochondrial intermediate peptidase (MIP), and the B-mating type locus with seven potential pheromone receptor genes and three potential pheromone precursor genes. To evaluate the benefits of the extract and chemicals from S. crispa, we adopted two approaches: (1) characterization of carbohydrate-active enzyme (CAZyme) genes and β-glucan synthase genes and the clusters of genes for the synthesis of second metabolites, such as terpenes, indoles and polyketides, and (2) identification of estrogenic activity in its mycelial extract. Two potential β-glucan synthase genes, ScrFKS1 and ScrFKS2, corresponding to types I and II, respectively, characteristic of Agaricomycetes mushrooms, were newly identified by the search for regions homologous to the reported features of β-glucan synthase genes; both contained the characteristic transmembrane regions and the regions homologous to the catalytic domain of the yeast β-glucan synthase gene FKS1. Rapid estrogenic cell-signaling and DNA microarray-based transcriptome analyses revealed the presence of a new category of chemicals with estrogenic activity, silent estrogens, in the extract. The elucidation of the S. crispa genome and its genes will expand the potential of this organism for medicinal and pharmacological purposes.
Highlights
Sparassis crispa, alternatively known as cauliflower mushroom in English or Hanabiratake in Japanese, has been used for food and as a traditional and modern medicine[1]
A 39.0-Mb genome sequence was obtained by assembling approximately 21.3-Gbp reads (>500 × coverage; data not shown) (Table 1). This genome sequence assembly consisted of 32 contigs with an N50 length of 3.18 Mb and L50 of 5 (Fig. 1; Table S1)
S. crispa has been known as a source of natural products with bioactive properties, such as for nutraceutical[31], medicinal[32,33] and cosmetic[34] applications
Summary
Alternatively known as cauliflower mushroom in English or Hanabiratake in Japanese, has been used for food and as a traditional and modern medicine[1]. A type of polysaccharide, β-1,3-glucan (β-glucan), which is abundantly obtained from the fruiting body of S. crispa and has polysaccharide chains linked by β-1,3-glycosidic bonds, has been highlighted because of its potential benefits, such as for prevention of cardiovascular diseases and cancer, due to its immunomodulatory or immunostimulative effects[3]. Β-glucan has not been confirmed to be effective for all expected diseases and symptoms, chemicals other than β-glucan with respective activities have been considered[2]. Phytoestrogens, plant-derived chemicals with estrogenic activity, have been considered as beneficial agents for menopausal syndromes, cardioprotection, neuroprotection and anti-carcinogenesis[5]. We report the genomic structure of S. crispa (strain Scrmy26), and its genes identified by next-generation sequencing and RNA-seq-based transcriptome analysis. We further explored beneficial usages of S. crispa by two different approaches: finding new β-glucan synthase genes by genome and protein analyses, and identifying new compounds with estrogenic activity by bioassays
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