Whole genome sequence of an edible and medicinal mushroom, Hericium erinaceus (Basidiomycota, Fungi)

Integrative Analysis of Transcriptome and Metabolome Sheds Light on Flavonoid Biosynthesis in the Fruiting Body of Stropharia rugosoannulata

Flavonoids are a diverse family of natural compounds that are widely distributed in plants and play a critical role in plant growth, development, and stress adaptation. In recent years, the biosynthesis of flavonoids in plants has been well-researched, with the successive discovery of key genes driving this process. However, the regulation of flavonoid biosynthesis in fungi remains unclear. Stropharia rugosoannulata is an edible mushroom known for its high nutritional and pharmacological value, with flavonoids being one of its main active components. To investigate the flavonoid content of S. rugosoannulata, a study was conducted to extract and determine the total flavonoids at four stages: young mushroom (Ym), gill (Gi), maturation (Ma), and parachute-opening (Po). The findings revealed a gradual increase in total flavonoid concentration as the fruiting body developed, with significant variations observed between the Ym, Gi, and Ma stages. Subsequently, we used UPLC-MS/MS and transcriptome sequencing (RNA-seq) to quantify the flavonoids and identify regulatory genes of Ym, Gi, and Ma. In total, 53 flavonoid-related metabolites and 6726 differentially expressed genes (DEGs) were identified. Through KEGG pathway enrichment analysis, we identified 59 structural genes encoding flavonoid biosynthesis-related enzymes, most of which were up-regulated during the development of the fruiting body, consistent with the accumulation of flavonoids. This research led to the establishment of a comprehensive transcriptional metabolic regulatory network encompassing flavonoids, flavonoid synthases, and transcription factors (TFs). This represents the first systematic exploration of the molecular mechanism of flavonoids in the fruiting of fungi, offering a foundation for further research on flavonoid mechanisms and the breeding of high-quality S. rugosoannulata.

The complete mitochondrial genome of Hericium erinaceus (Bull.:Fr.) Pers., 1797 (Russulales, Basidiomycota): an edible and medicinal fungus

Hericium erinaceus (Bull.:Fr.) Pers., 1797, is an edible and medicinal fungus found in China. In this study, specimens of H. erinaceus HE0021 were collected from southeastern China (Yunhe County, Lishui City, Zhejiang Province, 28°7'12″N, 119°34'12″E). The whole mitochondrial genome of H. erinaceus HE0021 was sequenced using next-generation sequencing (NGS) technology, which comprised 15 protein-coding genes (PCGs), 27 transfer RNAs (tRNAs), two ribosomal RNAs, with a total length of 83,518 base pairs (bp). The results of the phylogenetic analysis show that H. erinaceus and H. coralloides were clustered in the same clade. The complete mitogenome sequence provides essential data for the subsequent investigation of Hericium and Russulales.

Whole genome sequencing and annotation of Daedaleopsis sinensis, a wood-decaying fungus significantly degrading lignocellulose

Daedaleopsis sinensis is a fungus that grows on wood and secretes a series of enzymes to degrade cellulose, hemicellulose, and lignin and cause wood rot decay. Wood-decaying fungi have ecological, economic, edible, and medicinal functions. Furthermore, the use of microorganisms to biodegrade lignocellulose has high application value. Genome sequencing has allowed microorganisms to be analyzed from the aspects of genome characteristics, genome function annotation, metabolic pathways, and comparative genomics. Subsequently, the relevant information regarding lignocellulosic degradation has been mined by bioinformatics. Here, we sequenced and analyzed the genome of D. sinensis for the first time. A 51.67-Mb genome sequence was assembled to 24 contigs, which led to the prediction of 12,153 protein-coding genes. Kyoto Encyclopedia of Genes and Genomes database analysis of the D. sinensis data revealed that 3,831 genes are involved in almost 120 metabolic pathways. According to the Carbohydrate-Active Enzyme database, 481 enzymes are found in D. sinensis, of which glycoside hydrolases are the most abundant. The genome sequence of D. sinensis provides insights into its lignocellulosic degradation and subsequent applications.

Acute Effects of Naturally Occurring Guayusa Tea and Nordic Lion's Mane Extracts on Cognitive Performance

The aim of this study was to assess the effects of guayusa extract and Nordic Lion's Mane (LM) on cognition. Using a randomized, double-blind, placebo-controlled, crossover design, we examined the effects of a single dose of 650 mg guayusa extract (AMT: AmaTea® Max) vs. 1 g Nordic-grown Lion's Mane (LM) vs. placebo (PL). Participants attended three testing visits consisting of neuropsychological tests (Go/No-go, N-Back, and Serial 7 s tasks) assessing performance, subjective assessments of cognitive perception, and vital signs. Each assessment was measured at baseline (pre-ingestion) and 1 and 2 h post ingestion. AMT significantly (p ≤ 0.05) improved the number of attempts during Serial 7s, total score, number of correct responses, total number of responses, and reaction time during N-Back and improved Go stimulus reaction time, but it reduced the percentage of correct responses in the No-go stimulus response during Go/No-go. LM significantly (p ≤ 0.05) improved the number of attempts during Serial 7s and reaction time during N-Back and improved Go stimulus reaction time in Go/No-go. AMT improved mental clarity, focus, concentration, mood, and productivity at 1 and 2 h (p < 0.05); the ability to tolerate stress at 1 h; and had greater ratings than LM and PL for mental clarity, focus, concentration, and productivity. PL improved focus and concentration at 1 h from baseline (p ≤ 0.05). AMT and LM improved subjective ratings of "happiness compared to peers" and "getting the most out of everything" (p < 0.05); however, this occurred earlier in LM (i.e., 1 h post ingestion). AMT uniquely elevated blood pressure from baseline. AMT significantly improved cognitive performance and self-perceived cognitive indices of affect over a 2 h period and perceptions of happiness 2 h post ingestion. In comparison, LM helped improve working memory, complex attention, and reaction time 2 h post ingestion and perceptions of happiness over a 2 h period.

Decoding the chromosome-scale genome of the nutrient-rich Agaricus subrufescens: a resource for fungal biology and biotechnology

Agaricus subrufescens, also known as the "sun mushroom," has significant nutritional and medicinal value. However, its short shelf life due to the browning process results in post-harvest losses unless it's quickly dehydrated. This restricts its availability to consumers in the form of capsules. A genome sequence of A. subrufescens may lead to new cultivation alternatives or the application of gene editing strategies to delay the browning process. We assembled a chromosome-scale genome using a hybrid approach combining Illumina and Nanopore sequencing. The genome was assembled into 13 chromosomes and 31 unplaced scaffolds, totaling 44.5 Mb with 96.5% completeness and 47.24% GC content. 14,332 protein-coding genes were identified, with 64.6% of the genome covered by genes and 23.41% transposable elements. The mitogenome was circularized and encoded fourteen typical mitochondrial genes. Four polyphenol oxidase (PPO) genes and the Mating-type locus were identified. Phylogenomic analysis supports the placement of A. subrufescens in the Agaricomycetes clade. This is the first available genome sequence of a strain of the "sun mushroom." Results are available through a Genome Browser (https://plantgenomics.ncc.unesp.br/gen.php?id=Asub) and can support further fungal biological and genomic studies.

Comparative Genomic Analysis and Metabolic Potential Profiling of a Novel Culinary-Medicinal Mushroom, Hericium rajendrae (Basidiomycota)

Hericium rajendrae is an emerging species in the genus Hericium with few members. Despite being highly regarded due to its rarity, knowledge about H. rajendrae remains limited. In this study, we sequenced, de novo assembled, and annotated the complete genome of H. rajendrae NPCB A08, isolated from the Qinling Mountains in Shaanxi, China, using the Illumina NovaSeq and Nanopore PromethION technologies. Comparative genomic analysis revealed similarities and differences among the genomes of H. rajendrae, H. erinaceus, and H. coralloides. Phylogenomic analysis revealed the divergence time of the Hericium genus, while transposon analysis revealed evolutionary characteristics of the genus. Gene family variation reflected the expansion and contraction of orthologous genes among Hericium species. Based on genomic bioinformation, we identified the candidate genes associated with the mating system, carbohydrate-active enzymes, and secondary metabolite biosynthesis. Furthermore, metabolite profiling and comparative gene clusters analysis provided strong evidence for the biosynthetic pathway of erinacines in H. rajendrae. This work provides the genome of H. rajendrae for the first time, and enriches the genomic content of the genus Hericium. These findings also facilitate the application of H. rajendrae in complementary drug research and functional food manufacturing, advancing the field of pharmaceutical and functional food production involving H. rajendrae.

A chromosome-scale genome and proteome draft of Tremella fuciformis

In this study, we first reported a high-quality chromosome-scale genome of Tremella fuciformis using Pacbio HiFi sequencing combining Hi-C technology. According to 21.6 Gb PacBio HiFi reads and 18.1 Gb Hi-C valid reads, we drafted a T. fuciformis genome of 27.38 Mb assigned to 10 chromosomes, with the contig N50 of 2.28 Mb, GC content of 56.51 %, BUSCOs completeness of 93.1 % and consensus quality value of 33.7. The following annotation of genomic components predicted 5,171 repeat sequences, 283 RNAs, and 10,150 protein-coding genes. Next, the intracellular proteins at three differential life stages of T. fuciformis (conidium, hyphal and fruiting body) were identified by the shot-gun proteomics. 6,823 canonical proteins (68.1 % of predicted proteome) have been identified with protein FDR cut-off of 0.01, establishing the first proteome draft of predicted protein-coding genes of T. fuciformis. Finally, 24 T. fuciformis polysaccharides (TPS) biosynthesis-related genes in mycelia were identified by comparative transcriptomics and proteomics, which may be more active than in conidium and revealed the TPS biosynthesis process in mycelia. This present study elucidated T. fuciformis genome composition and organization, drafted its associated proteome, and provided a genome-view of TPS biosynthesis, which will be a powerful platform for biological and genetic studies in T. fuciformis.

Lessons on fruiting body morphogenesis from genomes and transcriptomes of Agaricomycetes

Fruiting bodies (sporocarps, sporophores or basidiomata) of mushroom-forming fungi (Agaricomycetes) are among the most complex structures produced by fungi. Unlike vegetative hyphae, fruiting bodies grow determinately and follow a genetically encoded developmental program that orchestrates their growth, tissue differentiation and sexual sporulation. In spite of more than a century of research, our understanding of the molecular details of fruiting body morphogenesis is still limited and a general synthesis on the genetics of this complex process is lacking. In this paper, we aim at a comprehensive identification of conserved genes related to fruiting body morphogenesis and distil novel functional hypotheses for functionally poorly characterised ones. As a result of this analysis, we report 921 conserved developmentally expressed gene families, only a few dozens of which have previously been reported to be involved in fruiting body development. Based on literature data, conserved expression patterns and functional annotations, we provide hypotheses on the potential role of these gene families in fruiting body development, yielding the most complete description of molecular processes in fruiting body morphogenesis to date. We discuss genes related to the initiation of fruiting, differentiation, growth, cell surface and cell wall, defence, transcriptional regulation as well as signal transduction. Based on these data we derive a general model of fruiting body development, which includes an early, proliferative phase that is mostly concerned with laying out the mushroom body plan (via cell division and differentiation), and a second phase of growth via cell expansion as well as meiotic events and sporulation. Altogether, our discussions cover 1 480 genes of Coprinopsis cinerea, and their orthologs in Agaricus bisporus, Cyclocybe aegerita, Armillaria ostoyae, Auriculariopsis ampla, Laccaria bicolor, Lentinula edodes, Lentinus tigrinus, Mycena kentingensis, Phanerochaete chrysosporium, Pleurotus ostreatus, and Schizophyllum commune, providing functional hypotheses for ~10 % of genes in the genomes of these species. Although experimental evidence for the role of these genes will need to be established in the future, our data provide a roadmap for guiding functional analyses of fruiting related genes in the Agaricomycetes. We anticipate that the gene compendium presented here, combined with developments in functional genomics approaches will contribute to uncovering the genetic bases of one of the most spectacular multicellular developmental processes in fungi. Citation: Nagy LG, Vonk PJ, Künzler M, Földi C, Virágh M, Ohm RA, Hennicke F, Bálint B, Csernetics Á, Hegedüs B, Hou Z, Liu XB, Nan S, M. Pareek M, Sahu N, Szathmári B, Varga T, Wu W, Yang X, Merényi Z (2023). Lessons on fruiting body morphogenesis from genomes and transcriptomes of Agaricomycetes. Studies in Mycology 104: 1-85. doi: 10.3114/sim.2022.104.01.

The First Whole Genome Sequencing of Agaricus bitorquis and Its Metabolite Profiling

Agaricus bitorquis, an emerging wild mushroom with remarkable biological activities and a distinctive oversized mushroom shape, has gained increasing attention in recent years. Despite its status as an important resource of wild edible fungi, knowledge about this mushroom is still limited. In this study, we used the Illumina NovaSeq and Nanopore PromethION platforms to sequence, de novo assemble, and annotate the whole genome and mitochondrial genome (mitogenome) of the A. bitorquis strain BH01 isolated from Bosten Lake, Xinjiang Province, China. Using the genome-based biological information, we identified candidate genes associated with mating type and carbohydrate-active enzymes in A. bitorquis. Cluster analysis based on P450 of basidiomycetes revealed the types of P450 members of A. bitorquis. Comparative genomic, mitogenomic, and phylogenetic analyses were also performed, revealing interspecific differences and evolutionary features of A. bitorquis and A. bisporus. In addition, the molecular network of metabolites was investigated, highlighting differences in the chemical composition and content of the fruiting bodies of A. bitorquis and A. bisporus. The genome sequencing provides a comprehensive understanding and knowledge of A. bitorquis and the genus Agaricus mushrooms. This work provides valuable insights into the potential for artificial cultivation and molecular breeding of A. bitorquis, which will facilitate the development of A. bitorquis in the field of edible mushrooms and functional food manufacture.

High-efficient production of mushroom polyketide compounds in a platform host Aspergillus oryzae

BACKGROUND

Orsellinic acid (2,4-dihydroxy-6-methylbenzoic acid, OA) and its structural analog o-Orsellinaldehyde, have become widely used intermediates in clinical drugs synthesis. Although the research on the biosynthesis of such compounds has made significant progress, due to the lack of suitable hosts, there is still far from the industrial production of such compounds based on synthetic biology.

RESULTS

With the help of genome mining, we found a polyketide synthase (PKS, HerA) in the genome of the Hericium erinaceus, which shares 60% amino acid sequence homology with ArmB from Armillaria mellea, an identified PKS capable of synthesizing OA. To characterize the function of HerA, we cloned herA and heterologously expressed it in Aspergillus oryzae, and successfully detected the production of OA. Subsequently, the introduction of an incomplete PKS (Pks5) from Ustilago maydis containing only three domains (AMP-ACP-R), which was into herA-containing A. oryzae, the resulted in the production of o-Orsellinaldehyde. Considering the economic value of OA and o-Orsellinaldehyde, we then optimized the yield of these compounds in A. oryzae. The screening showed that when maltose was used as carbon source, the yields of OA and o-Orsellinaldehyde were 57.68 mg/L and 15.71 mg/L respectively, while the yields were 340.41 mg/Kg and 84.79 mg/Kg respectively in rice medium for 10 days.

CONCLUSIONS

Herein, we successfully expressed the genes of basidiomycetes using A. oryzae heterologous host. As a fungus of ascomycetes, which not only correctly splices genes of basidiomycetes containing multiple introns, but also efficiently produces their metabolites. This study highlights that A. oryzae is an excellent host for the heterologous production of fungal natural products, and has the potential to become an efficient chassis for the production of basidiomycete secondary metabolites in synthetic biology.

Genome, transcriptome, and metabolome analyses provide new insights into the resource development in an edible fungus Dictyophora indusiata

Dictyophora indusiata (Vent. Ex Pers.) Fisch. (DI) is an edible and medicinal fungus widely used in East Asian countries. However, during DI cultivation, the formation of fruiting bodies cannot be regulated, which leads to yield and quality losses. The present study performed a combined genome, transcriptome, and metabolome analysis of DI. Using Nanopore and Illumina sequencing approaches, we created the DI reference genome, which was 67.32 Mb long with 323 contigs. We identified 19,909 coding genes on this genome, of which 46 gene clusters were related to terpenoid synthesis. Subsequent transcriptome sequencing using five DI tissues (cap, indusia, mycelia, stipe, and volva) showed high expression levels of genes in the cap, indicating the tissue's importance in regulating the fruiting body formation. Meanwhile, the metabolome analysis identified 728 metabolites from the five tissues. Mycelium was rich in choline, while volva was rich in dendronobilin; stipe had monosaccharides as the primary component, and the cap was the main source of indole acetic acid (IAA) synthesis. We confirmed the importance of tryptophan metabolism for DI fruiting body differentiation based on KEGG pathway analysis. Finally, the combined multiomics analysis identified three new genes related to IAA synthesis of the tryptophan metabolic pathway in the cap, which may regulate DI fruiting body synthesis and improve DI quality. Thus, the study's findings expand our understanding of resource development and the molecular mechanisms underlying DI development and differentiation. However, the current genome is still a rough draft that needs to be strengthened.

Increasing the production of the bioactive compounds in medicinal mushrooms: an omics perspective

Macroscopic fungi, mainly higher basidiomycetes and some ascomycetes, are considered medicinal mushrooms and have long been used in different areas due to their pharmaceutically/nutritionally valuable bioactive compounds. However, the low production of these bioactive metabolites considerably limits the utilization of medicinal mushrooms both in commerce and clinical trials. As a result, many attempts, ranging from conventional methods to novel approaches, have been made to improve their production. The novel strategies include conducting omics investigations, constructing genome-scale metabolic models, and metabolic engineering. So far, genomics and the combined use of different omics studies are the most utilized omics analyses in medicinal mushroom research (both with 31% contribution), while metabolomics (with 4% contribution) is the least. This article is the first attempt for reviewing omics investigations in medicinal mushrooms with the ultimate aim of bioactive compound overproduction. In this regard, the role of these studies and systems biology in elucidating biosynthetic pathways of bioactive compounds and their contribution to metabolic engineering will be highlighted. Also, limitations of omics investigations and strategies for overcoming them will be provided in order to facilitate the overproduction of valuable bioactive metabolites in these valuable organisms.

The bHLH-zip transcription factor SREBP regulates triterpenoid and lipid metabolisms in the medicinal fungus Ganoderma lingzhi

Ganoderic acids (GAs) are well recognized as important pharmacological components of the medicinal species belonging to the basidiomycete genus Ganoderma. However, transcription factors directly regulating the expression of GA biosynthesis genes remain poorly understood. Here, the genome of Ganoderma lingzhi is de novo sequenced. Using DNA affinity purification sequencing, we identify putative targets of the transcription factor sterol regulatory element-binding protein (SREBP), including the genes of triterpenoid synthesis and lipid metabolism. Interactions between SREBP and the targets are verified by electrophoretic mobility gel shift assay. RNA-seq shows that SREBP targets, mevalonate kinase and 3-hydroxy-3-methylglutaryl coenzyme A synthetase in mevalonate pathway, sterol isomerase and lanosterol 14-demethylase in ergosterol biosynthesis, are significantly upregulated in the SREBP overexpression (OE::SREBP) strain. In addition, 3 targets involved in glycerophospholipid/glycerolipid metabolism are upregulated. Then, the contents of mevalonic acid, lanosterol, ergosterol and 13 different GAs as well as a variety of lipids are significantly increased in this strain. Furthermore, the effects of SREBP overexpression on triterpenoid and lipid metabolisms are recovered when OE::SREBP strain are treated with exogenous fatostatin, a specific inhibitor of SREBP. Taken together, our genome-wide study clarify the role of SREBP in triterpenoid and lipid metabolisms of G. lingzhi.

Complete genome sequences and comparative secretomic analysis for the industrially cultivated edible mushroom Lyophyllum decastes reveals insights on evolution and lignocellulose degradation potential

Lyophyllum decastes, also known as Luronggu in China, is a culinary edible and medicinal mushroom that was widely cultivated in China in recent years. In the present study, the complete high-quality genome of two mating compatible L. decastes strain was sequenced. The L. decastes LRG-d1-1 genome consists of 47.7 Mb in 15 contigs with a contig N90 of 2.08 Mb and 14,499 predicted gene models. Phylogenetic analysis revealed that L. decastes exhibits a close evolutionary relationship to the Termitomyces and Hypsizygus genus and was diverged from H. marmoreus  ~ 45.53 Mya ago. Mating A loci of L. decastes compose of five and four HD genes in two monokaryotic strains, respectively. Mating B loci compose of five STE genes in both two monokaryotic strains. To accelerate the cross-breeding process, we designed four pairs of specific primers and successfully detected both mating types in L. decastes. As a wood-rotting mushroom, a total of 541 genes accounting for 577 CAZymes were identified in the genome of L. decastes. Proteomic analysis revealed that 1,071 proteins including 182 CAZymes and 258 secreted enzymes were identified from four groups (PDB, PDB + bran, PDB + cotton hull, and PDB + sawdust). Two laccases and a quinone reductase were strongly overproduced in lignin-rich cultures, and the laccases were among the top-3 secreted proteins, suggesting an important role in the synergistic decomposition of lignin. These results revealed the robustness of the lignocellulose degradation capacity of L. decastes. This is the first study to provide insights into the evolution and lignocellulose degradation of L. decastes.

A high-quality genome assembly of Lactarius hatsudake strain JH5

Lactarius hatsudake is a species of Lactarius commonly found in pine forests, is edible with a delicious and nutritious fruiting body, and exhibits medicinal properties. It is an ideal natural multifunctional food with bioactive components including fungal polysaccharides, crude fiber, unsaturated fatty acids, nucleic acid derivatives, various amino acids, and vitamins. However, biological and genomic analyses of this mycorrhizal mushroom are sparse, thereby hindering large-scale cultivation. Previously, we isolated and screened L. hatsudake JH5 strains and have applied our garnered knowledge to the large-scale cultivation of mycorrhizal seedlings. In this study, we produced a high-quality genome assembly of L. hatsudake JH5 by combining Illumina paired-end and PacBio single molecule real-time sequencing, resulting in PacBio single molecule real-time reads of 7.67 Gb and Illumina Pair-End reads of 1,560 Mb. Based on the distribution of k-mer frequencies, the genome size of this strain was estimated to be 63.84 Mb (1.14% heterozygosity). Based on de novo genome assembly, the final genome size was determined to be 76.7 Mb, with scaffold N50 of 223.2 kb and N90 of 54.5 kb, and a GC content of 54.38%. BUSCO assessment showed that genome completeness was 89.0%. The N50 length of the JH5 genome was 43.6% longer than that of the previously published L. hatsudake MG20 genome. This high-quality L. hatsudake genome assembly will facilitate research on the functional genome, molecular breeding, yield enhancement, and sustainability of L. hatsudake cultivation.

Characteristics of the Genome, Transcriptome and Ganoderic Acid of the Medicinal Fungus Ganoderma lingzhi

Ganoderma (Ganodermaceae) is a genus of edible and medicinal mushrooms that create a diverse set of bioactive compounds. Ganoderma lingzhi has been famous in China for more than 2000 years for its medicinal properties. However, the genome information of G. lingzhi has not been characterized. Here, we characterized its 49.15-Mb genome, encoding 13,125 predicted genes which were sequenced by the Illumina and PacBio platform. A wide spectrum of carbohydrate-active enzymes, with a total number of 519 CAZymes were identified in G. lingzhi. Then, the genes involved in sexual recognition and ganoderic acid (GA, key bioactive metabolite) biosynthesis were characterized. In addition, we identified and deduced the possible structures of 20 main GA constituents by UPLC-ESI-MS/MS, including a new special ganochlearic acid A. Furthermore, 3996 novel transcripts were discovered, and 9276 genes were predicted to have the possibility of alternative splicing from RNA-Seq data. The alternative splicing genes were enriched for functional categories involved in protein processing, endocytosis, and metabolic activities by KEGG. These genomic, transcriptomic, and GA constituents’ resources would enrich the toolbox for biological, genetic, and secondary metabolic pathways studies in G. lingzhi.

Genomic and Metabolomic Analyses of the Medicinal Fungus Inonotus hispidus for Its Metabolite's Biosynthesis and Medicinal Application

Inonotus hispidus mushroom is a traditional medicinal fungus with anti-cancer, antioxidation, and immunomodulatory activities, and it is used in folk medicine as a treatment for indigestion, cancer, diabetes, and gastric illnesses. Although I. hispidus is recognized as a rare edible medicinal macrofungi, its genomic sequence and biosynthesis potential of secondary metabolites have not been investigated. In this study, using Illumina NovaSeq combined with the PacBio platform, we sequenced and de novo assembled the whole genome of NPCB_001, a wild I. hispidus isolate from the Aksu area of Xinjiang Province, China. Comparative genomic and phylogenomic analyses reveal interspecific differences and evolutionary traits in the genus Inonotus. Bioinformatics analysis identified candidate genes associated with mating type, polysaccharide synthesis, carbohydrate-active enzymes, and secondary metabolite biosynthesis. Additionally, molecular networks of metabolites exhibit differences in chemical composition and content between fruiting bodies and mycelium, as well as association clusters of related compounds. The deciphering of the genome of I. hispidus will deepen the understanding of the biosynthesis of bioactive components, open the path for future biosynthesis research, and promote the application of Inonotus in the fields of drug research and functional food manufacturing.

Transcriptome Analysis Revealed the Mechanism of Inhibition of Saprophytic Growth of Sparassis latifolia by Excessive Oxalic Acid

Sparassis latifolia, a highly valued edible fungus, is a crucial medicinal and food resource owing to its rich active ingredients and pharmacological effects. Excessive oxalic acid secreted on a pine-sawdust-dominated substrate inhibits its mycelial growth, and severely restricts the wider development of its cultivation. However, the mechanism underlying the relationship between oxalic acid and slow mycelial growth remains unclear. The present study reported the transcriptome-based response of S. latifolia induced by different oxalic acid concentrations. In total, 9206 differentially expressed genes were identified through comparisons of three groups; 4587 genes were down-regulated and 5109 were up-regulated. Transcriptome analysis revealed that excessive oxalic acid mainly down-regulates the expression of genes related to carbohydrate utilization pathways, energy metabolism, amino acid metabolism, protein synthesis metabolism, glycan biosynthesis, and signal transduction pathways. Moreover, genes encoding for wood-degrading enzymes were predominantly down-regulated in the mycelia treated with excessive oxalic acid. Taken together, the study results provide a speculative mechanism underlying the inhibition of saprophytic growth by excessive oxalic acid and a foundation for further research on the growth of S. latifolia mycelia.

Chromosome-Level Genome Sequences, Comparative Genomic Analyses, and Secondary-Metabolite Biosynthesis Evaluation of the Medicinal Edible Mushroom Laetiporus sulphureus

Laetiporus sulphureus mushroom is a complementary and alternative medicine that has anticancer, antioxidation, and analgesic effects and immunomodulatory activity; it is used as a treatment for cough and rheumatism and is a functional food that can improve physical fitness. Even though L. sulphureus has garnered considerable biotechnological and pharmacological interest due to its excellent cellulose-degrading ability and diverse biological activities, its biosynthetic potential regarding polysaccharides and secondary metabolites has not been thoroughly examined. In this study, we sequenced and assembled the whole genome of a wild L. sulphureus isolate, NWAFU-1, from the Qinling Mountains in China. Comparative genomes analysis revealed genomic differences between subspecies, and phylogenomic analysis revealed evolutionary divergence as well as genome expansion and contraction of individual Polyporaceae family species. Bioinformatics investigation identified candidate genes associated with mating type, polysaccharide synthesis, carbohydrate-active enzymes, and secondary-metabolite biosynthesis, which included multiple terpenoids, nonribosomal peptides, and polyketides. The locations of biosynthetic core genes were mapped and displayed on chromosomes and contigs. Totals of 143 proteins from 126 coding genes were identified and divided into 14 cytochrome P450 families. Furthermore, the biosynthetic network of tetracyclic triterpenoid active components was postulated by genome mining of related genes combined with the molecular network of metabolites. The genome analysis of L. sulphureus in this study improves the understanding of the biosynthesis of active compounds, which will lay a theoretical foundation for subsequent research on active-compound biosynthesis and promote the application of Laetiporus in the field of drug research and functional-food creation. IMPORTANCE L. sulphureus is a parasitic basidiomycete fungus that causes brown rot. The fruiting bodies of L. sulphureus are used as ancient medicines in China and Europe to cure cancer, analgesia, cough, and rheumatism and are considered a functional food that regulates the body and improves health. L. sulphureus was inferred to be a tetrapolar system based on a high-quality genome, which will aid molecular breeding and artificial farming. Screening polysaccharide synthesis candidate genes and comparing carbohydrate-associated genes in brown-rot basidiomycetes help understand their growth. Identifying core genes for secondary-metabolite biosynthesis, gene cluster family analysis, and comparative cluster analysis will guide heterologous-biosynthesis investigations of these genes and help elucidate the biosynthetic pathways for L. sulphureus bioactive natural components. The biosynthesis network of tetracyclic triterpenes was mapped using metabolite profiling and genome scanning. This work explores the biosynthetic capacity of L. sulphureus-derived natural products and lays the foundation for biosynthetic studies of them.

Whole-Genome Sequencing and Comparative Genomics Analysis of the Wild Edible Mushroom (Gomphus purpuraceus) Provide Insights into Its Potential Food Application and Artificial Domestication

Gomphus purpuraceus (Iwade) Yokoyama is a species of wild fungi that grows in southwest China, considered an edible and medicinal fungus with potential commercial prospects. However, the detailed mechanisms related to the development of mycelium and the formation of the fruiting body are unclear. To obtain a comprehensive overview of genetic features, whole-genome and comparative genomics analyses of G. purpuraceus were performed. High-quality DNA was extracted from the mycelium, which was isolated from a fresh fruiting body of G. purpuraceus. The DNA sample was subjected to sequencing using Illumina and Oxford Nanopore sequencing platforms. A genome assembly totaling 40.15 Mb in 50 contigs with an N50 length of 2.06 Mb was generated, and 8705 putative predicted genes were found. Subsequently, phylogenetic analysis revealed a close evolutionary relationship between G. purpuraceus and Gomphus bonarii. Moreover, a total of 403 carbohydrate-active enzymes (CAZymes) were identified in G. purpuraceus, which included 147 glycoside hydrolases (GHs), 85 glycosyl transferases (GTs), 8 polysaccharide lyases (PLs), 76 carbohydrate esterases (CEs), 57 auxiliary activities (AAs) and 30 carbohydrate-binding modules (CBMs). Compared with the other 13 fungi (Laccaria bicolor, Russula virescens, Boletus edulis, etc.), the number and distribution of CAZymes in G. purpuraceus were similar to other mycorrhizal fungi. Furthermore, the optimization of culture medium for G. purpuraceus showed the efficient utilization of disaccharides such as sucrose and maltose. The genome of G. purpuraceus provides new insights into its niche, food applications and potential artificial domestication.

Whole-genome sequence of a high-temperature edible mushroom Pleurotus giganteus (zhudugu)

Most of the sequenced wood-rotting edible mushroom produce fruiting body at relatively low temperatures. Little information has been known about the high-temperature wood-rotting mushroom. Here, we performed de novo sequencing and assembly of the genome of a high-temperature edible mushroom Pleurotus giganteus from a monokaryotic strain zhudugu2 using the Illumina and Pac-Bio CLR sequencing technologies. P. giganteus, also known as Zhudugu in China, is a well-known culinary edible mushroom that has been widely distributed and cultivated in China, Southeast Asia, and South Asia. The genome consists of 40.00 Mb in 27 contigs with a contig N50 of 4.384 Mb. Phylogenetic analysis reveals that P. giganteus and other strains in Pleurotus clustered in one clade. Phylogenetic analysis and average nucleotide identity analysis indicated that the P. giganteus genome showed a closer relationship with other Pleurotus species. Chromosome collinearity analysis revealed a high level of collinearity between P. ostreatus and P. giganteus. There are 12,628 protein-coding genes annotated in this monoploid genome. A total of 481 enzymes accounting for 514 carbohydrate-active enzymes (CAZymes) terms were identified in the P. giganteus genome, including 15 laccases and 10 class II peroxidases predicted in the genome, which revealed the robustness of lignocellulose degradation capacity of P. giganteus. The mating-A type locus of P. giganteus consisted of a pair of homeodomain mating-type genes HD1 and HD2. The mating-B type locus of P. giganteus consisted of at least four pheromone receptor genes and three pheromone genes. The genome is not only beneficial for the genome-assisted breeding of this mushroom but also helps us to understand the high-temperature tolerance of the edible mushroom.

Genome sequencing of Inonotus obliquus reveals insights into candidate genes involved in secondary metabolite biosynthesis

Background

Inonotus obliquus is an important edible and medicinal mushroom that was shown to have many pharmacological activities in preclinical trials, including anti-inflammatory, antitumor, immunomodulatory, and antioxidant effects. However, the biosynthesis of these pharmacological components has rarely been reported. The lack of genomic information has hindered further molecular characterization of this mushroom.

Results

In this study, we report the genome of I. obliquus using a combined high-throughput Illumina NovaSeq with Oxford Nanopore PromethION sequencing platform. The de novo assembled 38.18 Mb I. obliquus genome was determined to harbor 12,525 predicted protein-coding genes, with 81.83% of them having detectable sequence similarities to others available in public databases. Phylogenetic analysis revealed the close evolutionary relationship of I. obliquus with Fomitiporia mediterranea and Sanghuangporus baumii in the Hymenochaetales clade. According to the distribution of reproduction-related genes, we predict that this mushroom possesses a tetrapolar heterothallic reproductive system. The I. obliquus genome was found to encode a repertoire of enzymes involved in carbohydrate metabolism, along with 135 cytochrome P450 proteins. The genome annotation revealed genes encoding key enzymes responsible for secondary metabolite biosynthesis, such as polysaccharides, polyketides, and terpenoids. Among them, we found four polyketide synthases and 20 sesquiterpenoid synthases belonging to four more types of cyclization mechanism, as well as 13 putative biosynthesis gene clusters involved in terpenoid synthesis in I. obliquus.

Conclusions

To the best of our knowledge, this is the first reported genome of I. obliquus; we discussed its genome characteristics and functional annotations in detail and predicted secondary metabolic biosynthesis-related genes, which provides genomic information for future studies on its associated molecular mechanism.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08511-x.

Genome and Comparative Transcriptome Dissection Provide Insights Into Molecular Mechanisms of Sclerotium Formation in Culinary-Medicinal Mushroom Pleurotus tuber-regium

Pleurotus tuber-regium is an edible and medicinal sclerotium-producing mushroom. The sclerotia of this mushroom also serve as food and folk medicine. Based on the description of its monokaryon genome, sequenced with Illumina and PacBio sequencing technologies, comparative transcriptomic analysis using RNA sequencing (RNA-seq) was employed to study its mechanism of sclerotium formation. The de novo assembled genome is 35.82 Mb in size with a N50 scaffold size of 4.29 Mb and encodes 12,173 putative proteins. Expression analysis demonstrated that 1,146 and 1,249 genes were upregulated and downregulated with the formation of sclerotia, respectively. The differentially expressed genes were associated with substrate decomposition, the oxidation-reduction process, cell wall synthesis, and other biological processes in P. tuber-regium. These genomic and transcriptomic resources provide useful information for the mechanism underlying sclerotium formation in P. tuber-regium.

Whole Genome Sequencing and Annotation of Naematelia aurantialba (Basidiomycota, Edible-Medicinal Fungi)

Naematelia aurantialba is a rare edible fungus with both nutritional and medicinal values and especially rich in bioactive polysaccharides. However, due to the lack of genomic information, researches on the mining of active compounds, artificial breeding and cultivation, genetics, and molecular biology are limited. To facilitate the medicinal and food applications of N. aurantialba, we sequenced and analyzed the whole genome of N. aurantialba for the first time. The 21-Mb genome contained 15 contigs, and a total of 5860 protein-coding genes were predicted. The genome sequence shows that 296 genes are related to polysaccharide synthesis, including 15 genes related to nucleoside-activated sugar synthesis and 11 genes related to glucan synthesis. The genome also contains genes and gene clusters for the synthesis of other active substances, including terpenoids, unsaturated fatty acids, and bioactive proteins. In addition, it was also found that N. aurantialba was more closely related to Naematelia encephala than to Tremella fuciformis. In short, this study provides a reference for molecular cognition of N. aurantialba and related researches.

Genome of Ganoderma Species Provides Insights Into the Evolution, Conifers Substrate Utilization, and Terpene Synthesis for Ganoderma tsugae

Ganoderma tsugae is an endemic medicinal mushroom in Northeast China, providing important source of pharmaceutical product. Comparing with other Ganoderma species, wild G. tsugae can utilize coniferous wood. However, functional genes related to medicinal component synthesis and the genetic mechanism of conifer substrate utilization is still obscure. Here, we assembled a high-quality G. tsugae genome with 18 contigs and 98.5% BUSCO genes and performed the comparative genomics with other Ganoderma species. G. tsugae diverged from their common ancestor of G. lingzhi and G. sinense about 21 million years ago. Genes in G. tsugae-specific and G. tsugae-expanded gene families, such as salh, phea, cyp53a1, and cyp102a, and positively selected genes, such as glpk and amie, were functionally enriched in plant-pathogen interaction, benzoate degradation, and fanconi anemia pathway. Those functional genes might contribute to conifer substrate utilization of G. tsugae. Meanwhile, gene families in the terpene synthesis were identified and genome-wide SNP variants were detected in population. Finally, the study provided valuable genomic resources and offered useful hints for the functional gene mapping and investigation of key gene contributing to conifer cultivation substrate utilization and medicinal component biosynthesis.

Whole-genome assembly of Ganoderma leucocontextum (Ganodermataceae, Fungi) discovered from the Tibetan Plateau of China

Ganoderma leucocontextum, a newly discovered species of Ganodermataceae in China, has diverse pharmacological activities. G. leucocontextum was widely cultivated in southwest China, but the systematic genetic study has been impeded by the lack of a reference genome. Herein, we present the first whole-genome assembly of G. leucocontextum based on the Illumina and Nanopore platform from high-quality DNA extracted from a monokaryon strain (DH-8). The generated genome was 50.05 Mb in size with a N50 scaffold size of 3.06 Mb, 78,206 coding sequences and 13,390 putative genes. Genome completeness was assessed using the Benchmarking Universal Single-Copy Orthologs (BUSCO) tool, which identified 96.55% of the 280 Fungi BUSCO genes. Furthermore, differences in functional genes of secondary metabolites (terpenoids) were analyzed between G. leucocontextum and G. lucidum. G. leucocontextum has more genes related to terpenoids synthesis compared to G. lucidum, which may be one of the reasons why they exhibit different biological activities. This is the first genome assembly and annotation for G. leucocontextum, which would enrich the toolbox for biological and genetic studies in G. leucocontextum.

The First Whole Genome Sequencing of Sanghuangporus sanghuang Provides Insights into Its Medicinal Application and Evolution

Sanghuangporus is a medicinal macrofungal genus typified by S. sanghuang, the very species utilized in traditional Chinese medicines by Chinese ancient people. To facilitate the medicinal application of S. sanghuang, we, for the first time, perform its genome sequencing and analyses from a monokaryon strain. A 33.34 Mb genome sequence was assembled to 26 contigs, which lead to the prediction of 8278 protein-coding genes. From these genes, the potential biosynthesis pathway of sesquiterpenoids was, for the first time, identified from Sanghuangporus, besides that of triterpenoids. While polysaccharides are the main medicinal metabolites in S. sanghuang, flavonoids are especially abundant medicinal metabolites comparing with other medicinal macrofungal groups. From the genomic perspective, S. sanghuang has a tetrapolar heterothallic mating system, and has its special nutritional strategy and advantageous medicinal properties compared with S. baumii and S. vaninii. A phylogenomics analysis indicates that Sanghuangporus emerged 15.39 million years ago and S. sanghuang has a closer phylogenetic relationship with S. baumii than S. vaninii. However, S. sanghuang shares a higher region of synteny and more orthologous genes, including carbohydrate-active enzymes with S. vaninii than S. baumii. A comparative genomics analysis with S. baumii and S. vaninii indicates that species diversification within Sanghuangporus may be driven by the translocation and translocation plus inversion of genome sequences, while the expansion and contraction of gene families may contribute to the host specificity of Sanghuangporus species. In general, the genome sequence of S. sanghuang provides insights into its medicinal application and evolution.

Analyses of transcriptomes and the first complete genome of Leucocalocybe mongolica provide new insights into phylogenetic relationships and conservation

In this study, we report a de novo assembly of the first high-quality genome for a wild mushroom species Leucocalocybe mongolica (LM). We performed high-throughput transcriptome sequencing to analyze the genetic basis for the life history of LM. Our results show that the genome size of LM is 46.0 Mb, including 26 contigs with a contig N50 size of 3.6 Mb. In total, we predicted 11,599 protein-coding genes, of which 65.7% (7630) could be aligned with high confidence to annotated homologous genes in other species. We performed phylogenetic analyses using genes form 3269 single-copy gene families and showed support for distinguishing LM from the genus Tricholoma (L.) P.Kumm., in which it is sometimes circumscribed. We believe that one reason for limited wild occurrences of LM may be the loss of key metabolic genes, especially carbohydrate-active enzymes (CAZymes), based on comparisons with other closely related species. The results of our transcriptome analyses between vegetative (mycelia) and reproductive (fruiting bodies) organs indicated that changes in gene expression among some key CAZyme genes may help to determine the switch from asexual to sexual reproduction. Taken together, our genomic and transcriptome data for LM comprise a valuable resource for both understanding the evolutionary and life history of this species.

Landscape of meiotic crossovers in Hericium erinaceus

Meiotic crossover shows marked interspecific and intraspecific variation, and knowledge about the molecular mechanism of crossover variation remains limited. Herein, we described the genome-wide scanning of crossover in one mushroom-forming fungus Hericium erinaceus. Utilizing the whole-genome single-nucleotide polymorphism (SNP) data-sets of a 127 F₁ haploid progeny, we localized a total of 1316 crossover events and found that they were more likely to occur in the genic than intergenic regions. More than 30 % of the crossovers were concentrated in 59 crossover hotspots that were preferentially located close to chromosome ends. We then examined the genomic features around crossover hotspots. Results showed that the crossover hotspots were associated with increased gene density and guanine-cytosine (GC) content. An 8-bp GC-rich motif (GCGTCAGC) was found to be significantly enriched in these hotspots. The presence of mating-type loci affected the crossover at local scale rather than the overall crossover number. In order to dissect the genetic mechanisms shaping crossover variation, we then conducted quantitative trait locus (QTL) mapping for the total crossovers (TCO) and the crossover events that solely occurred within hotspots (HCO). Genome-wide QTL scanning identified four TCO-QTLs and two HCO-QTLs, which all located within or next to the crossover-hotspots. Crossover variations were shaped by multiple small-effect loci, with individual QTL contributing 6.9 %-11.7 % of variation. A few recombination pathway genes, including Spo11, Msh5, and Smc5 were found to be co-localized with the mapped crossover QTLs. Taken together, findings of this study offer insights into the crossover distribution and genetic factors conferring crossover variation in H. erinaceus, and advance our understandings for meiotic recombination in mushroom-forming fungi.

Immunomodulatory Effects of Edible and Medicinal Mushrooms and Their Bioactive Immunoregulatory Products

Mushrooms have been valued as food and health supplements by humans for centuries. They are rich in dietary fiber, essential amino acids, minerals, and many bioactive compounds, especially those related to human immune system functions. Mushrooms contain diverse immunoregulatory compounds such as terpenes and terpenoids, lectins, fungal immunomodulatory proteins (FIPs) and polysaccharides. The distributions of these compounds differ among mushroom species and their potent immune modulation activities vary depending on their core structures and fraction composition chemical modifications. Here we review the current status of clinical studies on immunomodulatory activities of mushrooms and mushroom products. The potential mechanisms for their activities both in vitro and in vivo were summarized. We describe the approaches that have been used in the development and application of bioactive compounds extracted from mushrooms. These developments have led to the commercialization of a large number of mushroom products. Finally, we discuss the problems in pharmacological applications of mushrooms and mushroom products and highlight a few areas that should be improved before immunomodulatory compounds from mushrooms can be widely used as therapeutic agents.

Metal concentration and health risk assessment of wild mushrooms collected from the Black Sea region of Turkey

Mushrooms are rich sources of organic nutrients (especially proteins). However, they can excessively accumulate metals in their fruiting bodies that pose a risk to human health. The aim of this study was the determination of Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn contents, daily intake, and health risk index values of some mushroom species collected from the eastern Black Sea region of Turkey (Arsin, Trabzon). The samples were collected from hazelnut gardens that are free from industrial pollution and have a low population density. As a result of elemental analysis, it was determined that the concentration ranges of Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn in the mushrooms were as follows: 0.29-9.11, 0.04-3.70, 0.01-8.29, 0.18-20.82, 3.1-79.8, 5.2-673.0, 14.9-752.0, 63.0-7769.0 mg/kg dry weight. Daily intakes of all the elements were found to be below the reference dose in Fistulina hepatica, Hydnum repandum, Macrolepiota procera, and Tapinella atrotomentosa. Amanita caesarea, Agrocybe praecox, Amanita vaginata, Cantharellus cibarius, Craterellus cornucopioides, Daedalea quercina, Gymnopus dryophilus, Ganoderma lucidum, and Infundibulicybe gibba were found to have high risk index values especially with respect to Cd, Co, and Pb. According to Pearson correlation analysis, the correlations between Fe-Mn (0.840, p < 0.01) and Pb-Ni (0.7540, p < 0.01) couples are significant.