Phylogenomics of the psychoactive mushroom genus Psilocybe and evolution of the psilocybin biosynthetic gene cluster.

Psychoactive mushrooms in the genus Psilocybe have immense cultural value and have been used for centuries in Mesoamerica. Despite the recent surge of interest in these mushrooms due to the psychotherapeutic potential of their natural alkaloid psilocybin, their phylogeny and taxonomy remain substantially incomplete. Moreover, the recent elucidation of the psilocybin biosynthetic gene cluster is known for only five of ~165 species of Psilocybe, four of which belong to only one of two major clades. We set out to improve the phylogeny of Psilocybe using shotgun sequencing of fungarium specimens, from which we obtained 71 metagenomes including from 23 types, and conducting phylogenomic analysis of 2,983 single-copy gene families to generate a fully supported phylogeny. Molecular clock analysis suggests the stem lineage of Psilocybe arose ~67 mya and diversified ~56 mya. We also show that psilocybin biosynthesis first arose in Psilocybe, with 4 to 5 possible horizontal transfers to other mushrooms between 40 and 9 mya. Moreover, predicted orthologs of the psilocybin biosynthetic genes revealed two distinct gene orders within the biosynthetic gene cluster that corresponds to a deep split within the genus, possibly a signature of two independent acquisitions of the cluster within Psilocybe.

Stage-specific transposon activity in the life cycle of the fairy-ring mushroom Marasmius oreades.

Genetic variability can be generated by different mechanisms, and across the life cycle. Many basidiomycete fungi have an extended somatic stage, during which each cell carries two genetically distinct haploid nuclei (dikaryosis), resulting from fusion of two compatible monokaryotic individuals. Recent findings have revealed remarkable genome stability at the nucleotide level during dikaryotic growth in these organisms, but whether this pattern extends to mutations affecting large genomic regions remains unknown. Furthermore, despite high genome integrity during dikaryosis, basidiomycete populations are not devoid of genetic diversity, begging the question of when this diversity is introduced. Here, we used a Marasmius oreades fairy ring to investigate the rise of large-scale variants during mono- and dikaryosis. By separating the two nuclear genotypes from four fruiting bodies and generating complete genome assemblies, we gained access to investigate genomic changes of any size. We found that during dikaryotic growth in nature the genome stayed intact, but after separating the nucleotypes into monokaryons, a considerable amount of structural variation started to accumulate, driven to large extent by transposons. Transposon insertions were also found in monokaryotic single-meiospore isolates. Hence, we show that genome integrity in basidiomycetes can be interrupted during monokaryosis, leading to genomic rearrangements and increased activity of transposable elements. We suggest that genetic diversification is disproportionate between life cycle stages in mushroom-forming fungi, so that the short-lived monokaryotic growth stage is more prone to genetic changes than the dikaryotic stage.

Genome-wide characterization and metabolite profiling of Cyathus olla: insights into the biosynthesis of medicinal compounds.

Cyathus olla, belonging to the genus Cyathus within the order Agaricales, is renowned for its bird's nest-like fruiting bodies and has been utilized in folk medicine. However, its genome remains poorly understood. To investigate genomic diversity within the genus Cyathus and elucidate biosynthetic pathways for medicinal compounds, we generated a high-quality genome assembly of C. olla with fourteen chromosomes. The comparative genome analysis revealed variations in both genomes and specific functional genes within the genus Cyathus. Phylogenomic and gene family variation analyses provided insights into evolutionary divergence, as well as genome expansion and contraction in individual Cyathus species and 36 typical Basidiomycota. Furthermore, analysis of LTR-RT and Ka/Ks revealed apparent whole-genome duplication (WGD) events its genome. Through genome mining and metabolite profiling, we identified the biosynthetic gene cluster (BGC) for cyathane diterpenes from C. olla. Furthermore, we predicted 32 BGCs, containing 41 core genes, involved in other bioactive metabolites. These findings represent a valuable genomic resource that will enhance our understanding of Cyathus species genetic diversity. The genome analysis of C. olla provides insights into the biosynthesis of medicinal compounds and establishes a fundamental basis for future investigations into the genetic basis of chemodiversity in this significant medicinal fungus.

Identification and fungicides sensitivity evaluation of the causal agent of cobweb disease on Lyophyllum decastes in China.

BACKGROUND: Cobweb disease is a fungal disease that commonly affects the cultivation and production of edible mushrooms, leading to serious yield and economic losses. It is considered a major fungal disease in the realm of edible mushrooms. The symptoms of cobweb disease were found during the cultivation of Lyophyllum decastes. This study aimed to identify the causative pathogen of cobweb disease and evaluate effective fungicides, providing valuable insights for field control and management of L. decastes cobweb disease. RESULTS: The causal agent of cobweb disease was isolated from samples infected and identified as Cladobotryum mycophilum based on morphological and cultural characteristics, as well as multi-locus phylogeny analysis (ITS, RPB1, RPB2, and TEF1-α). Pathogenicity tests further confirmed C. mycophilum as the responsible pathogen for this condition. Among the selected fungicides, Prochloraz-manganese chloride complex, Trifloxystrobin, tebuconazole, and Difenoconazole exhibited significant inhibitory effects on the pathogen's mycelium, with EC50 values of 0.076 µg/mL, 0.173 µg/mL, and 0.364 µg/mL, respectively. These fungicides can serve as references for future field control of cobweb disease in L. decastes. CONCLUSION: This study is the first report of C. mycophilum as the causing agent of cobweb disease in L. decastes in China. Notably, Prochloraz-manganese chloride complex demonstrated the strongest inhibitory efficacy against C. mycophilum.

Wickerhamomyces corioli f.a., sp. nov., a novel yeast species discovered in two mushroom species.

Two yeast strains, designated as 19-39-3 and 19-40-2, obtained from the fruiting bodies of Trametes versicolor and Marasmius siccus collected in Yunwu Mountain Forest Park, PR China, have been identified as representing a novel asexual ascomycetous yeast species. From the results of phylogenetic analyses of the sequences of the D1/D2 domains of the large subunit (LSU) rRNA, small subunit (SSU) rRNA and translation elongation factor 1-α (TEF1) genes, it was determined that these strains represent a member of the genus Wickerhamomyces, with Wickerhamomyces alni and Candida ulmi as the closest relatives. The novel species exhibited 6.6 and 6.7% differences in the D1/D2 domains compared with W. alni and C. ulmi, respectively. Additionally, distinct biochemical and physiological differences were observed between the novel species and its related counterparts. No sexual reproduction was observed in these strains, leading to the proposal of the name Wickerhamomyces corioli f.a., sp. nov. for this newly discovered species.

Complete mitochondrial genomes of edible mushrooms: features, evolution, and phylogeny.

Edible mushrooms are an important food source with high nutritional and medicinal value. They are a useful source for studying phylogenetic evolution and species divergence. The exploration of the evolutionary relationships among these species conventionally involves analyzing sequence variations within their complete mitochondrial genomes, which range from 31,854 bp (Cordyceps militaris) to 197,486 bp (Grifolia frondosa). The study of the complete mitochondrial genomes of edible mushrooms has emerged as a critical field of research, providing important insights into fungal genetic makeup, evolution, and phylogenetic relationships. This review explores the mitochondrial genome structures of various edible mushroom species, highlighting their unique features and evolutionary adaptations. By analyzing these genomes, robust phylogenetic frameworks are constructed to elucidate mushrooms lineage relationships. Furthermore, the exploration of different variations of mitochondrial DNA presents novel opportunities for enhancing mushroom cultivation biotechnology and medicinal applications. The mitochondrial genomic features are essential for improving agricultural practices and ensuring food security through improved crop productivity, disease resistance, and nutritional qualities. The current knowledge about the mitochondrial genomes of edible mushrooms is summarized in this review, emphasising their significance in both scientific research and practical applications in bioinformatics and medicine.

Pleurotus ostreatus as a model mushroom in genetics, cell biology, and material sciences.

Pleurotus ostreatus, also known as the oyster mushroom, is a popular edible mushroom cultivated worldwide. This review aims to survey recent progress in the molecular genetics of this fungus and demonstrate its potential as a model mushroom for future research. The development of modern molecular genetic techniques and genome sequencing technologies has resulted in breakthroughs in mushroom science. With efficient transformation protocols and multiple selection markers, a powerful toolbox, including techniques such as gene knockout and genome editing, has been developed, and numerous new findings are accumulating in P. ostreatus. These include molecular mechanisms of wood component degradation, sexual development, protein secretion systems, and cell wall structure. Furthermore, these techniques enable the identification of new horizons in enzymology, biochemistry, cell biology, and material science through protein engineering, fluorescence microscopy, and molecular breeding. KEY POINTS: • Various genetic techniques are available in Pleurotus ostreatus. • P. ostreatus can be used as an alternative model mushroom in genetic analyses. • New frontiers in mushroom science are being developed using the fungus.

Enhanced extracellular production of laccase in Coprinopsis cinerea by silencing chitinase gene.

Laccase, a copper-containing polyphenol oxidase, is an important green biocatalyst. In this study, Laccase Lcc5 was homologous recombinantly expressed in Coprinopsis cinerea and a novel strategy of silencing chitinase gene expression was used to enhance recombinant Lcc5 extracellular yield. Two critical chitinase genes, ChiEn1 and ChiE2, were selected by analyzing the transcriptome data of C. cinerea FA2222, and their silent expression was performed by RNA interference (RNAi). It was found that silencing either ChiEn1 or ChiE2 reduced sporulation and growth rate, and increased cell wall sensitivity, but had no significant effect on mycelial branching. Among them, the extracellular laccase activity of the ChiE2-silenced engineered strain Cclcc5-antiChiE2-5 and the control Cclcc5-13 reached the highest values (38.2 and 25.5 U/mL, respectively) at 250 and 150 rpm agitation speeds, corresponding to productivity of 0.35 and 0.19 U/mL·h, respectively, in a 3-L fermenter culture. Moreover, since Cclcc5-antiChiE2-5 could withstand greater shear forces, its extracellular laccase activity was 2.6-fold higher than that of Cclcc5-13 when the agitation speed was all at 250 rpm. To our knowledge, this is the first report of enhanced recombinant laccase production in C. cinerea by silencing the chitinase gene. This study will pave the way for laccase industrial production and accelerate the development of a C. cinerea high-expression system. KEY POINTS: • ChiEn1 and ChiE2 are critical chitinase genes in C. cinerea FA2222 genome. • Chitinase gene silencing enhanced the tolerance of C. cinerea to shear forces. • High homologous production of Lcc5 is achieved by fermentation in a 3-L fermenter.

Nakazawaea tricholomae f.a., sp. nov., a Novel Ascomycetous Yeast Species Isolated from Two Mushroom Species in China.

Two yeast strains designated as 20-27-1 and 20-28 were isolated from the fruiting bodies of Tricholoma gambosum and Marasmius maximus, respectively, which were collected in Wudaogou, Weichang county, Chengde area, Hebei Province, China. The multi-locus analysis of the sequences of the rDNA ITS, D1/D2 LSU, and SSU regions, together with partial sequences of two protein-coding genes RPB1 and TEF1 indicates that the two strains are closely related to Nakazawaea ernobii and Nakazawaea holstii, showing the similarity values of 99.3-98.7%, 97.2-97.1%, 91.9-92.5%, and 84.6% in D1/D2 LSU, ITS, TEF1, and RPB1, respectively. Physiologically, the two strains are different from N. ernobii and N. holstii in the assimilation of melibiose, inulin, and DL-lactic acid. Both the phenotypic and phylogenetic analyses indicate that those two strains represent a novel species in the genus Nakazawaea, for which the name Nakazawaea tricholomae f.a., sp. nov. (Fungal Names: FN 571492) is proposed.

Coprinopsis cinerea dioxygenase is an oxygenase forming 10(S)-hydroperoxide of linoleic acid, essential for mushroom alcohol, 1-octen-3-ol, synthesis.

1-Octen-3-ol is a volatile oxylipin found ubiquitously in Basidiomycota and Ascomycota. The biosynthetic pathway forming 1-octen-3-ol from linoleic acid via the linoleic acid 10(S)-hydroperoxide was characterized 40 years ago in mushrooms, yet the enzymes involved are not identified. The dioxygenase 1 and 2 genes (Ccdox1 and Ccdox2) in the mushroom Coprinopsis cinerea contain an N-terminal cyclooxygenase-like heme peroxidase domain and a C-terminal cytochrome P450-related domain. Herein, we show that recombinant CcDOX1 is responsible for dioxygenation of linoleic acid to form the 10(S)-hydroperoxide, the first step in 1-octen-3-ol synthesis, whereas CcDOX2 conceivably forms linoleic acid 8-hydroperoxide. We demonstrate that KO of the Ccdox1 gene suppressed 1-octen-3-ol synthesis, although added linoleic acid 10(S)-hydroperoxide was still efficiently converted. The P450-related domain of CcDOX1 lacks the characteristic Cys heme ligand and the evidence indicates that a second uncharacterized enzyme converts the 10(S)-hydroperoxide to 1-octen-3-ol. Additionally, we determined the gene KO strain (ΔCcdox1) was less attractive to fruit fly larvae, while the feeding behavior of fungus gnats on ΔCcdox1 mycelia showed little difference from that on the mycelia of the WT strain. The proliferation of fungivorous nematodes on ΔCcdox1 mycelia was similar to or slightly worse than that on WT mycelia. Thus, 1-octen-3-ol seems to be an attractive compound involved in emitter-receiver ecological communication in mushrooms.

Integrated omic profiling of the medicinal mushroom Inonotus obliquus under submerged conditions.

BACKGROUND: The Inonotus obliquus mushroom, a wondrous fungus boasting edible and medicinal qualities, has been widely used as a folk medicine and shown to have many potential pharmacological secondary metabolites. The purpose of this study was to supply a global landscape of genome-based integrated omic analysis of the fungus under lab-growth conditions. RESULTS: This study presented a genome with high accuracy and completeness using the Pacbio Sequel II third-generation sequencing method. The de novo assembled fungal genome was 36.13 Mb, and contained 8352 predicted protein-coding genes, of which 365 carbohydrate-active enzyme (CAZyme)-coding genes and 19 biosynthetic gene clusters (BCGs) for secondary metabolites were identified. Comparative transcriptomic and proteomic analysis revealed a global view of differential metabolic change between seed and fermentation culture, and demonstrated positive correlations between transcription and expression levels of 157 differentially expressed genes involved in the metabolism of amino acids, fatty acids, secondary metabolites, antioxidant and immune responses. Facilitated by the widely targeted metabolomic approach, a total of 307 secondary substances were identified and quantified, with a significant increase in the production of antioxidant polyphenols. CONCLUSION: This study provided the comprehensive analysis of the fungus Inonotus obliquus, and supplied fundamental information for further screening of promising target metabolites and exploring the link between the genome and metabolites.

Comparative genomic analysis of five coprinoid mushrooms species.

Although coprinoid mushrooms are widely known for the phenomenon of deliquescence and production of fungal laccases and extracellular peroxygenases, the genome structure and genetic diversity of coprinoid mushroom species have not been extensively studied. To reveal the genomic structure and diversity in coprinoid mushroom species, the genomes of five coprinoid mushroom species were compared and analyzed. A total of 24,303 orthologous gene families, including 89,462 genes, were identified in the five species. The numbers of core, softcore, dispensable, and private genes were 5617 (25.6%), 1628 (7.4%), 2083 (9.5%), and 12,574 (57.4%), respectively. Differentiation time analysis revealed that Coprinellus micaceus and Coprinellus angulatus differentiated approximately 181.0 million years ago. Coprinopsis cinerea and Coprinopsis marcescibilis differentiated approximately 131.0 million years ago, and they were differentiated from Candolleomyces aberdarensis approximately 176.0 million years ago. Gene family contraction and expansion analyses showed that 1465 genes and 532 gene families were expanded, and 95 genes and 134 gene families were contracted. Ninety-five laccase-coding genes were detected in the five species, and the distribution of the laccase-coding genes in the five species was not uniform. These data provide a reference for a deeper understanding of the genetic structure of the genomes of coprinoid mushroom species. Furthermore, this study provides a reference for follow-up studies on the genome structure of coprinoid mushroom species and the diversity of specific functional genes.

The evolution and ecology of psilocybin in nature.

Fungi produce diverse metabolites that can have antimicrobial, antifungal, antifeedant, or psychoactive properties. Among these metabolites are the tryptamine-derived compounds psilocybin, its precursors, and natural derivatives (collectively referred to as psiloids), which have played significant roles in human society and culture. The high allocation of nitrogen to psiloids in mushrooms, along with evidence of convergent evolution and horizontal transfer of psilocybin genes, suggest they provide a selective benefit to some fungi. However, no precise ecological roles of psilocybin have been experimentally determined. The structural and functional similarities of psiloids to serotonin, an essential neurotransmitter in animals, suggest that they may enhance the fitness of fungi through interference with serotonergic processes. However, other ecological mechanisms of psiloids have been proposed. Here, we review the literature pertinent to psilocybin ecology and propose potential adaptive advantages psiloids may confer to fungi.

Structure and ecological function of the soil microbiome associated with 'Sanghuang' mushrooms suffering from fungal diseases.

BACKGROUND: The most serious challenges in medicinal 'Sanghuang' mushroom production are the fungal diseases caused by various molds. Application of biological agents has been regarded as a potential crop disease management strategy. Here, the soil microbiome associated with 'Sanghuang' mushroom affected by fungal diseases grown under field cultivation (FC) and hanging cultivation (HC) was characterized using culture-dependent and culture-independent methods. RESULTS: A total of 12,525 operational taxonomic units (OTUs) and 168 pure cultures were obtained using high-throughput sequencing and a culture-dependent method, respectively. From high-throughput sequencing, we found that HC samples had more OTUs, higher α-diversity, and greater microbial community complexity than FC samples. Analysis of ß-diversity divided the soil microbes into two groups according to cultivation mode. Basidiomycota (48.6%) and Ascomycota (46.5%) were the two dominant fungal phyla in FC samples, with the representative genera Trichoderma (56.3%), Coprinellus (29.4%) and Discosia (4.8%), while only the phylum Ascomycota (84.5%) was predominant in HC samples, with the representative genera Discosia (34.0%), Trichoderma (30.2%), Penicillium (14.9%), and Aspergillus (7.8%). Notably, Trichoderma was predominant in both the culture-independent and culture-dependent analyses, with Trichoderma sp. FZ0005 showing high host pathogenicity. Among the 87 culturable bacteria, 15 exhibited varying extents of antifungal activity against Trichoderma sp. FZ0005, with three strains of Bacillus spp. (HX0037, HX0016, and HX0039) showing outstanding antifungal capacity. CONCLUSIONS: Overall, our results suggest that Trichoderma is the major causal agent of 'Sanghuang' fungal diseases and that Bacillus strains may be used as biocontrol agents in 'Sanghuang' cultivation.

Kodamaea samutsakhonensis f.a., sp. nov., a novel ascomycetous yeast species isolated from wild mushrooms in Thailand.

Two strains of genus Kodamaea, representing a novel anamorphic yeast species, were isolated from two samples of Marasmiellus sp. collected in Thailand. Analysis of the sequences of the internal transcribed spacer (ITS) regions and the D1/D2 domains of the large subunit (LSU) rRNA gene showed that the two strains differed by 27-42 nucleotide substitutions in the D1/D2 domains of the LSU rRNA gene and 7-34 nucleotide substitutions in the ITS region of a group of related species, Kodamaea smagusa CBS 11430T, Kodamaea fungicola JCM 10142T, Kodamaea plutei ATCC MYA-4329T, Kodamaea lidongshanica SD5S01T and Kodamaea jinghongensis NYNU 167162T. Phylogenetic analysis based on the concatenated sequences of the ITS and the D1/D2 domains of the LSU rRNA gene showed that the two strains were placed in the Kodamaea clade and clearly separated from other recognized species of the genus. Therefore, the two strains were assigned as a novel species of the genus Kodamaea, for which we propose the name Kodamaea samutsakhonensis f.a., sp. nov. The holotype is TBRC 16043T (=DMKU-BP19T) and the isotype is PYCC 9354. The MycoBank number of the novel species is MB 846490.

Yamadazyma sisaketensis f.a., sp. nov. and Yamadazyma koratensis f.a., sp. nov., two novel ascomycetous yeast species from mushrooms and cocoa leaves in Thailand, and reassignment of Candida andamanensis, Candida jaroonii and Candida songkhlaensis to the genus Yamadazyma.

Six strains representing two novel ascomycetous yeast species were isolated from mushroom fruiting bodies and cocoa leaves collected in Thailand. Analysis of the internal transcribed spacer (ITS) regions and the D1/D2 domains of the large subunit rRNA gene sequences showed that the six strains were divided into two groups. The first group consisted of four strains (DMKU-SSK46, DMKU-SK1, SCCL3-5 and SCCL19-3), that were closely related to the type strains of Candida conglobata, Candida insectorum, Yamadazyma dushanensis, Yamadazyma mexicana and Yamadazyma riverae, but with 12-14 (2.5-2.9 %) and 28-50 (5.4-8.8 %) nucleotide substitutions in the D1/D2 domains and the ITS regions, respectively. However, two strains (DMKU-KMY40 and DMKU-KO18) of the second group differed from a group of described species, Candida diddensiae, Candida dendronema, Candida germanica, Candida kanchanaburiensis, Candida naeodendra, Candida vaughaniae and Yamadazyma siamensis by 8-15 (1.5-2.8 %) and 45-53 (8.2-9.6 %) nucleotide substitutions in the D1/D2 domains and the ITS regions, respectively. Phylogenetic analysis based on the concatenated sequences of the ITS regions and D1/D2 domains showed that these strains represented two species of the Yamadazyma clade that were distinct from the other related species. Based on the phylogenetic analysis and phenotypic characteristics, these six strains were assigned to two novel species of the genus Yamadazyma, although formation of ascospores was not observed. Yamadazyma sisaketensis f.a., sp. nov., is proposed for the first group (four strains). The holotype is TBRC 17139T (ex-type culture: PYCC 9797). The MycoBank number is MB 849637. Yamadazyma koratensis f.a., sp. nov. is proposed for the second group (two strains). The holotype is TBRC 14868T (ex-type culture: PYCC 8907). The MycoBank number is MB 849638. In addition, it is proposed that Candida andamanensis, Candida jaroonii and Candida songkhlaensis are reassigned to the genus Yamadazyma as Yamadazyma andamanensis comb. nov., Y. jaroonii comb. nov. and Y. songkhlaensis comb. nov., respectively.

Bacterial communities associated with mushrooms in the Qinghai-Tibet Plateau are shaped by soil parameters.

Fungi capable of producing fruit bodies are essential food and medicine resources. Despite recent advances in the study of microbial communities in mycorrhizospheres, little is known about the bacterial communities contained in fruit bodies. Using high-throughput sequencing, we investigated the bacterial communities in four species of mushrooms located on the alpine meadow and saline-alkali soil of the Qinghai-Tibet Plateau (QTP). Proteobacteria (51.7% on average) and Actinobacteria (28.2% on average) were the dominant phyla in all of the sampled fairy ring fruit bodies, and Acidobacteria (27.5% on average) and Proteobacteria (25.7% on average) dominated their adjacent soils. For the Agria. Bitorquis, Actinobacteria was the dominant phylum in its fruit body (67.5% on average) and adjacent soils (65.9% on average). The alpha diversity (i.e., Chao1, Shannon, Richness, and Simpson indexes) of the bacterial communities in the fruit bodies were significantly lower than those in the soil samples. All of the fungi shared more than half of their bacterial phyla and 16.2% of their total operational taxonomic units (OTUs) with their adjacent soil. Moreover, NH4+ and pH were the key factors associated with bacterial communities in the fruit bodies and soils, respectively. These results indicate that the fungi tend to create a unique niche that selects for specific members of the bacterial community. Using culture-dependent methods, we also isolated 27 bacterial species belonging to three phyla and five classes from fruit bodies and soils. The strains isolated will be useful for future research on interactions between mushroom-forming fungi and their bacterial endosymbionts.

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.

Identification and morpho-molecular characterization of low spore strain in oyster mushroom.

BACKGROUND: Sporocarps of oyster mushroom liberate enormous spores and cause allergic reactions to workers involved in its cultivation. These spore-related allergies include stiffness or pain in the forearms, limbs, itchy throat, grogginess, and respiratory problems and are major problems during oyster mushroom cultivation. METHODS AND RESULTS: In this study, we have generated seven hybrids using single-spore isolates (SSIs) of Pleurotus ostreatus var. florida (DMRP-49) and P. ostreatus (DMRP-30). Chimera was observed during cultivation trial of these hybrids and led to the development of low spore-producing/sporeless strain (DMRP-395) as evident from spore print and microscopic analysis. Further, the cultivation trial of this sporeless strain revealed a bunchy fruiting pattern and required 20-24 °C temperature for fruiting. At par yield was observed in sporeless strain. Notably, a prominent infundibuliform-shaped pileus along with central attachment of stipe was observed in the sporeless strain. Moreover, genetic diversity and principal component biplot analysis revealed resemblance of sporeless strain with one of the parental strain, i.e., P. ostreatus var. florida (DMRP-49). CONCLUSIONS: The developed sporeless strain (DMRP-395) contains high protein and at par yield as compared with the control (DMRP-136). This sporeless strain will be helpful to reduce spore-related allergic responses in mushroom growers.