Biological characteristics of Cordyceps militaris single mating-type strains.

Cordyceps militaris has been extensively cultivated as a model cordyceps species for commercial purposes. Nevertheless, the problems related to strain degeneration and breeding technologies remain unresolved. This study assessed the physiology and fertility traits of six C. militaris strains with distinct origins and characteristics, focusing on single mating-type strains. The results demonstrated that the three identified strains (CMDB01, CMSY01, and CMJB02) were single mating-type possessing only one mating-type gene (MAT1-1). In contrast, the other three strains (CMXF07, CMXF09, and CMMS05) were the dual mating type. The MAT1-1 strains sourced from CMDB01, CMSY01, and CMJB02 consistently produced sporocarps but failed to generate ascospores. However, when paired with MAT1-2 strains, the MAT1-1 strains with slender fruiting bodies and normal morphology were fertile. The hyphal growth rate of single mating-type strains (CMDB01, CMSY01, and CMJB02) typically surpassed that of dual mating-type strains (CMXF07, CMXF09, and CMMS05). The growth rates of MAT1-2 and MAT1-1 strains were proportional to their ratios, such that a single mating-type strain with a higher ratio exhibited an increased growth rate. As C. militaris matured, the adenosine content decreased. In summary, the C. militaris strains that consistently produce sporocarps and have a single mating type are highly promising for production and breeding.

Transmission of Oyster Mushroom Spherical Virus to Progeny via Basidiospores and Horizontally to a New Host Pleurotus floridanus.

Mycoviruses are usually transmitted horizontally via hyphal anastomosis and vertically through sporulation in natural settings. Oyster mushroom spherical virus (OMSV) is a mycovirus that infects Pleurotus ostreatus, with horizontal transmission via hyphal anastomosis. However, whether OMSV can be vertically transmitted is unclear. This study aimed to investigate the transmission characteristics of OMSV to progeny via basidiospores and horizontally to a new host. A total of 37 single-basidiospore offspring were obtained from OMSV-infected P. ostreatus and Pleurotus pulmonarius for Western blot detection of OMSV. The OMSV-carrying rate among monokaryotic isolates was 19% in P. ostreatus and 44% in P. pulmonarius. Then, OMSV-free and OMSV-infected monokaryotic isolates were selected for hybridization with harvested dikaryotic progeny strains. Western blot analyses of the offspring revealed that the OMSV transmission efficiency was 50% in P. ostreatus and 75% in P. pulmonarius, indicating vertical transmission via sexual basidiospores. Furthermore, we observed the horizontal transfer of OMSV from P. pulmonarius to Pleurotus floridanus. OMSV infection in P. floridanus resulted in significant inhibition of mycelial growth and yield loss. This study was novel in reporting the vertical transmission of OMSV through basidiospores, and its infection and pathogenicity in a new host P. floridanus.

Oyster Mushroom Spherical Virus Crosses the Species Barrier and Is Pathogenic to a New Host Pleurotus pulmonarius.

Oyster mushroom spherical virus (OMSV) is a mycovirus with a positive-sense single-stranded RNA genome that infects the edible mushroom Pleurotus ostreatus. OMSV is horizontally transferred from an infected strain to a cured strain via mycelia. The infection results in significant inhibition of mycelial growth, malformation of fruiting bodies, and yield loss in oyster mushrooms. This study successfully transferred OMSV from P. ostreatus to Pleurotus pulmonarius. However, transmission was not successful in other Pleurotus species including P. citrinopileatus, P. eryngii, P. nebrodensis, and P. salmoneostramineus. The successful OMSV infection in P. pulmonarius was further verified with Western blot analysis using a newly prepared polyclonal antiserum against the OMSV coat protein. Furthermore, OMSV infection reduced the mycelial growth rate of P. pulmonarius. The OMSV-infected strain demonstrated abnormal performance including twisted mushrooms or irregular edge of the cap as well as reduced yield of fruiting bodies in P. pulmonarius, compared to the OMSV-free strain. This study is the first report on the infection and pathogenicity of OMSV to the new host P. pulmonarius. The data from this study therefore suggest that OMSV is a potential threat to P. pulmonarius.

Multiplex Detection of Pleurotus ostreatus Mycoviruses.

Mycoviruses are viruses that specifically infect and replicate in fungi. Several mycoviruses have been previously reported in Pleurotus ostreatus, including the oyster mushroom spherical virus (OMSV), oyster mushroom isometric virus (OMIV), Pleurotus ostreatus spherical virus (POSV), and Pleurotus ostreatus virus 1 (PoV1). This study was designed to develop a multiplex RT-PCR for simultaneous detection and differentiation of the four P. ostreatus mycoviruses. Four pairs of primers were designed from conserved regions based on the reported sequences and the multiplex RT-PCR products were 672 bp for OMSV, 540 bp for OMIV, 310 bp for POSV, and 200 bp for PoV1. The optimal annealing temperature of the multiplex RT-PCR was 62 °C and the detection limits of the plasmids were 100 fg for OMSV and OMIV and 1 pg for POSV and PoV1. This technique was successfully applied for the detection of OMSV, OMIV, and POSV from different P. ostreatus strains and the plasmid containing the PoV1 sequence. This methodology can serve as a powerful diagnostic tool for the survey of the incidence and epidemiology of the four P. ostreatus mycoviruses, further contributing to the prevention and treatment of mycoviral diseases in P. ostreatus.

Efficient extraction and antioxidant activity of polyphenols from Antrodia cinnamomea.

BACKGROUND: Antrodia cinnamomea, a rare medicinal fungus, has been increasingly studied in recent years because of its abundant secondary metabolites which are beneficial to humans. However, there is a lack of research on its polyphenols which are of good research value due to their antioxidant, anti-inflammatory, hypoglycemic and other activities. RESULTS: In this study, the effects of different extraction conditions on the yield of its polyphenols were investigated. Deep-Eutectic Solvents composed of choline chloride and malonic acid had the best extraction efficiency, with the optimal extraction conditions being as follows: a solid-liquid ratio of 40 mg/mL, an extraction temperature of 55 °C, an extraction time of 70 min and a DES with 20% water content. Under these conditions, the extraction yield of polyphenols reached 22.09 mg/g which was about 2 times that of alcohol-based extraction (10.95 mg/g). In vitro antioxidant test results further showed that polyphenols from A. cinnamomea had strong antioxidant activities. When the concentration of polyphenols reached 0.1 mg/mL of polyphenols, the scavenging activity of free radical basically reached its maximum, with values of 94.10%, 83.34% and 95.42% for DPPH, ABTS+ and ·OH scavenging. In this case, the corresponding IC50 values were 0.01, 0.014 and 0.007 mg/mL, respectively. CONCLUSIONS: This study lays the foundation for the efficient extraction and application of polyphenols from A. cinnamomea.

Optimization of Extraction Process and the Antioxidant Activity of Phenolics from Sanghuangporus baumii.

Sanghuangporus baumii, is a widely used medicinal fungus. The polyphenols extracted from this fungus exert antioxidant, anti-inflammatory, and hypoglycemic effects. In this study, polyphenols from the fruiting bodies of S. baumii were obtained using the deep eutectic solvent (DES) extraction method. The factors affecting the extraction yield were investigated at different conditions. Based on the results from single-factor experiments, response surface methodology was used to optimize the extraction conditions. The scavenging ability of the polyphenols on •OH, DPPH, and ABTS+ was determined. The results showed that the DES system composed of choline chloride and malic acid had the best extraction yield (6.37 mg/g). The optimal extraction parameters for response surface methodology were as follows: 42 min, 58 ℃, 1:34 solid-liquid (mg/mL), and water content of 39%. Under these conditions, the yield of polyphenols was the highest (12.58 mg/g). At 0.30 mg/mL, the scavenging ability of the polyphenols on •OH, DPPH, and ABTS+ was 95.71%, 91.08%, and 85.52%, respectively. Thus, the method using DES was more effective than the conventional method of extracting phenolic compounds from the fruiting bodies of S. baumii. Moreover, the extracted polyphenols exhibited potent antioxidant activity.

Making good use of the byproducts of cultivation: green synthesis and antibacterial effects of silver nanoparticles using the leaf extract of blueberry.

In this study, we made an effort to use blueberry leaves extract as a reducing and a capping agent to biosynthesize silver nanoparticles (AgNPs). The successful formation of AgNPs was confirmed with UV-visible spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. Furthermore, their antimicrobial activities against four kinds of multi drug resistant clinical pathogens and aquatic pathogens were investigated. The results showed that as-prepared AgNPs exhibited broad-spectrum antibacterial activities. The antibacterial effects of the AgNPs based on the structural damage and DNA degradation of the tested bacteria were also studied. The green synthesis of AgNPs using blueberry leaf extract, which provided a new idea on the use of the byproducts of blueberry harvesting.

Biogeochemical Approaches to Assess PAH Pollution in an Urban Waterway.

Biogeochemical approaches were applied to enhance the study on polycyclic aromatic hydrocarbon (PAH) pollution in an urban waterway. Chemical characterizations of PAHs in the studied area were identified, geochemical factors were revealed, and related mechanisms were discussed. It was found that, during summer, an early diagenetic process in the sediment could play a major role for the existence of high PAH concentrations, especially high molecular weight PAHs (≥ 4 rings), in the water column and sediment porewater. This effect could vary with tidal cycling, and higher PAH concentration in the water column would be expected during low tide. Other potential pollution sources were also evaluated in the studied creek. Results showed that pyrogenic sources dominated in the creek, generally. Nevertheless, petroleum products from a metal recycling plant could be an important point source to the waterway during wet weather. Comparing with previous studies in other waterways of the same watershed and published literature suggested that the limited toxicity to the ecosystem was only detected in sediments. More information needs to be collected during low tide for a more objective evaluation of PAH toxicity in the creek.

Comparative Analysis of Agronomic Traits, Yield, and Effective Components of Main Cultivated Ganoderma Mushrooms (Agaricomycetes) in China.

To assess the strain resources and address production challenges in Ganoderma cultivation. 150 Ganoderma strains were collected from 13 provinces in China. A comparative analysis of agronomic traits and effective components was conducted. Among the 150 strains, key agronomic traits measured were: average stipe diameter (15.92 mm), average stipe length (37.46 mm), average cap horizontal diameter (94.97 mm), average cap vertical diameter (64.21 mm), average cap thickness (15.22 mm), and average fruiting body weight (14.30 g). Based on these agronomic traits, four promising strains, namely, L08, L12, Z21, and Z39, were recommended for further cultivation and breeding. The average crude polysaccharide content ranged from 0.048% to 0.977%, and triterpenoids ranged from 0.804% to 2.010%. In addition, 73 triterpenoid compounds were identified, constituting 47.1% of the total compounds. Using a distance discrimination method, the types, and relative contents of triterpenoid compounds in 150 Ganoderma strains were classified, achieving 98% accuracy in G. lingzhi identification. The 16 triterpenoid components used for G. lingzhi identification included oleanolic acid, ursolic acid, 3ß-acetoxyergosta-7,22-dien-5α-ol, ganoderic acid DM, ganoderiol B, ganorderol A, ganoderic acid GS-1, tsugaric acid A, ganoderic acid GS-2, ganoderenic acid D, ganoderic acid Mf, ganoderic acid A, ganoderic acid K, ganoderic acid V, ganoderic acid G, and leucocontextin J. This study provides valuable insights for exploring and utilizing Ganoderma resources and for the development of new varieties.

Morphological and phylogenetic analyses reveal five new species of Porotheleaceae (Agaricales, Basidiomycota) from China.

The first occurrence of Marasmiellomycena and Pulverulina in the Chinese mycobiota are reported, M.tomentosa and P.flavoalba, two new species and M.albodescendens, a new combination, revealed by phylogenetic analyses and morphological study. These newly-recorded genera, Marasmiellomycena, which can be distinguished by their agaricoid basidiomata, dark-coloured stipe, sarcodimitic tramal structure, stipitipellis with yellow to yellowish-brown pigments and yellow-pigmented thick-walled caulocystidia and Pulverulina, which differs from other genera of Porotheleaceae by its pruinose stipe, decurrent lamellae, inamyloid basidiospores and absence of hymenial cystidia. We also formally describe three other new species of Porotheleaceae collected from Chinese temperate to subtropical zones of Fujian and Zhejiang Provinces: Clitocybulafuscostriata, Gerronemabrunneosquamulosum and Leucoinocybesubglobispora. Furthermore, we include the results of a phylogenetic analysis of Porotheleaceae, based on a multi-locus (ITS, nrLSU and rpb2) dataset. According to this analysis, Chrysomycena, Clitocybula, Delicatula, Hydropodia, Hydropus, Leucoinocybe, Marasmiellomycena, Megacollybia, Pulverulina, Trogia and Vizzinia are monophyletic. However, Gerronema is identified as polyphyletic and, additionally, Porotheleum does not form a monophyletic group either because Porotheleumparvulum and Porotheleumalbidum are "unassigned" in phylogenetic analysis. The results of our phylogenetic analyses, coupled with morphological observations, confirm recognition of these new taxa. Morphological descriptions, photographs, line drawings and comparisons with closely-related taxa are presented for the new species. A key to the 22 species belonging to nine genera of Porotheleaceae in China is also provided.

Revealing Brownish Mycena Diversity in China: New Discoveries and Taxonomic Insights.

Within the genus Mycena, species exhibiting brownish basidiomata present considerable challenges in identification due to similar coloration. This study underscores the significance of pileipellis types and cheilocystidia characteristics as critical in delimiting brownish Mycena species. To clarify the principal taxonomic characters and their utility in distinguishing between brownish Mycena species, a morphological taxonomy and phylogenetic analysis were performed. Five new species from China were introduced and characterized through a comprehensive morphological anatomy and phylogenetic substantiation: M. campanulatihemisphaerica sp. nov., M. digitifurcata sp. nov., M. kunyuensis sp. nov., M. limitis sp. nov., and M. oryzifluens sp. nov. Discussions of these taxa are supplemented with morphological illustrations. The phylogenetic relationships were inferred using Bayesian Inference and Maximum Likelihood methods based on sequences from the internal transcribed spacer and the large subunit regions of nuclear ribosomal RNA. With the addition of these five new species, the worldwide count of brownish Mycena increases to 94, and a key to the 29 known species of brownish Mycena from China is presented.

Effects of mating-type ratio imbalance on the degeneration of Cordyceps militaris subculture and preventative measures.

The rapid degeneration of Cordyceps militaris strains during subculture represents a bottleneck problem that affects production stability. This study explored the mechanism underlying this degeneration in three production and three wild-type strains of Cordyceps militaris, isolating single-conidium strains from each. The effects of subculturing on fructification in both original and single mating-type strains were compared. Changes in the ratio of the two mating types were analyzed in both original and degenerated strains. Based on these findings, the two mating strains were paired in different ratios to determine their effects on fruiting. The resulting five strains were heterokaryotic strains with both MAT1-1 and MAT1-2 mating-type genes. Strain jb-2 was a single mating type (MAT1-1) mutant strain that produced stable fruiting bodies but failed to produce ascospores. It was found that the loss of or imbalance in mating types was the main reason for the rapid degeneration of fruiting traits during subculture and that this occurred randomly in the MAT1-1 and MAT1-2 types. The strains differed significantly in their stability during subculture. Fruiting was stable in the single mating-type Jb-2 strain, and the eleventh-generation fruited normally. There were differences in yield between the production and wild strains after inoculation with spawn containing different proportions of mating types. The production strain was more stable when inoculated with strains with mating-type ratios of 1:9 to 9:1 without affecting the yield. However, the yield of the wild-type strain xf-1 was positively correlated with the proportion of the MAT1-2 type, while the other two strains showed no correlations. Subculturing single mating-type mycelia separately and mixing them before production effectively mitigated degeneration during subculture. For Cordyceps militaris breeding, selecting strains containing both mating types, which are insensitive to the proportion of mating-type genes, enhanced stability in subculture and reduced the risk of mating-type loss. Direct breeding of specific single-mating type strains to induce fruiting is thus an effective breeding strategy.

Population genetics provides insights into the important agronomic traits of Ganoderma cultivation varieties in China.

This study aimed to investigate the species diversity and genetic differentiation of the genome of the main cultivated strains of Ganoderma in China. Population genomics analysis was conducted based on 150 cultivated strains of Ganoderma collected nationwide. The results indicated that the main species currently cultivated in China were Ganoderma sichuanense and Ganoderma lucidum, with a minor proportion of Ganoderma sessile, Ganoderma weberianum, Ganoderma sinense, Ganoderma gibbosum and Ganoderma australe. A total of 336,506 high-quality single nucleotide polymorphism (SNP) loci were obtained through population evolution analysis. The Fst values were calculated using a 5-kb sliding window, which ranged from 0.11 to 0.74. This suggests varying degrees of genetic differentiation between populations and genetic exchange among varieties. On this basis, the genes related to the stipe length, cap color and branch phenotypes of Ganoderma were excavated, and the region with the top 1% ZFst value region was used as a candidate region. A total of 137, 270 and 222 candidate genes were identified in the aforementioned 3 phenotypes, respectively. Gene annotation revealed that genes associated with stipe length were mainly related to cell division and differentiation, including proteins such as Nse4 protein and DIM1 protein. The genes related to Ganoderma red color were mainly related to the metabolism of tryptophan and flavonoids. The genes related to the branch were mainly related to cytokinin synthesis, ABC transporter and cytochrome P450. This study provided 150 valuable genome resequencing data in assessing the diversity and genetic differentiation of Ganoderma and laid a foundation for agronomic trait analysis and the development of new varieties of Ganoderma.

Effect of addition of γ-poly glutamic acid on bacterial nanocellulose production under agitated culture conditions.

BACKGROUND: Bacterial nanocellulose (BNC), a natural polymer material, gained significant popularity among researchers and industry. It has great potential in areas, such as textile manufacturing, fiber-based paper, and packaging products, food industry, biomedical materials, and advanced functional bionanocomposites. The main current fermentation methods for BNC involved static culture, as the agitated culture methods had lower raw material conversion rates and resulted in non-uniform product formation. Currently, studies have shown that the production of BNC can be enhanced by incorporating specific additives into the culture medium. These additives included organic acids or polysaccharides. γ-Polyglutamic acid (γ-PGA), known for its high polymerization, excellent biodegradability, and environmental friendliness, has found extensive application in various industries including daily chemicals, medicine, food, and agriculture. RESULTS: In this particular study, 0.15 g/L of γ-PGA was incorporated as a medium additive to cultivate BNC under agitated culture conditions of 120 rpm and 30 â„ƒ. The BNC production increased remarkably by 209% in the medium with 0.15 g/L γ-PGA and initial pH of 5.0 compared to that in the standard medium, and BNC production increased by 7.3% in the medium with 0.06 g/L γ-PGA. The addition of γ-PGA as a medium additive resulted in significant improvements in BNC production. Similarly, at initial pH levels of 4.0 and 6.0, the BNC production also increased by 39.3% and 102.3%, respectively. To assess the characteristics of the BNC products, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis were used. The average diameter of BNC fibers, which was prepared from the medium adding 0.15 g/L γ-PGA, was twice thicker than that of BNC fibers prepared from the control culture medium. That might be because that polyglutamic acid relieved the BNC synthesis from the shear stress from the agitation. CONCLUSIONS: This experiment held great significance as it explored the use of a novel medium additive, γ-PGA, to improve the production and the glucose conversion rate in BNC fermentation. And the BNC fibers became thicker, with better thermal stability, higher crystallinity, and higher degree of polymerization (DPv). These findings lay a solid foundation for future large-scale fermentation production of BNC using bioreactors.

Transcriptome and metabolome profiling unveils the mechanisms of naphthalene acetic acid in promoting cordycepin synthesis in Cordyceps militaris.

Cordycepin, an important active substance in Cordyceps militaris, possesses antiviral and other beneficial activities. In addition, it has been reported to effectively promote the comprehensive treatment of COVID-19 and thus has become a research hotspot. The addition of naphthalene acetic acid (NAA) is known to significantly improve the yield of cordycepin; however, its related molecular mechanism remains unclear. We conducted a preliminary study on C. militaris with different concentrations of NAA. We found that treatment with different concentrations of NAA inhibited the growth of C. militaris, and an increase in its concentration significantly improved the cordycepin content. In addition, we conducted a transcriptome and metabolomics association analysis on C. militaris treated with NAA to understand the relevant metabolic pathway of cordycepin synthesis under NAA treatment and elucidate the relevant regulatory network of cordycepin synthesis. Weighted gene co-expression network analysis (WGCNA), transcriptome, and metabolome association analysis revealed that genes and metabolites encoding cordycepin synthesis in the purine metabolic pathway varied significantly with the concentration of NAA. Finally, we proposed a metabolic pathway by analyzing the relationship between gene-gene and gene-metabolite regulatory networks, including the interaction of cordycepin synthesis key genes; key metabolites; purine metabolism; TCA cycle; pentose phosphate pathway; alanine, aspartate, and glutamate metabolism; and histidine metabolism. In addition, we found the ABC transporter pathway to be significantly enriched. The ABC transporters are known to transport numerous amino acids, such as L-glutamate, and participate in the amino acid metabolism that affects the synthesis of cordycepin. Altogether, multiple channels work together to double the cordycepin yield, thereby providing an important reference for the molecular network relationship between the transcription and metabolism of cordycepin synthesis.

Analysis of genetic diversity among Chinese Pleurotus citrinopileatus Singer cultivars using two molecular marker systems (ISSRs and SRAPs) and morphological traits.

To evaluate the genetic diversity of Pleurotus citrinopileatus Singer cultivars in China, 20 P. citrinopileatus strains were analyzed using morphological traits, inter-simple sequence repeat (ISSR) and sequence-related amplified polymorphism (SRAP) molecular markers. Eleven ISSR primers amplified a total of 116 DNA fragments of which 96 (82.91%) were polymorphic, whereas 8 SRAP primer pairs amplified 69 fragments of which 65 (93.47%) were polymorphic. Phylogenetic trees constructed on the basis of ISSR, SRAP, and combined ISSR/SRAP analyses using the Unweighted Pair-group Method with Arithmetic Averages method distributed the 20 strains into three or six major groups. The grouping exhibited great similarity and was generally consistent with their morphological characters and antagonism test, which indicated a high level of genetic diversity among P. citrinopileatus Singer and relationship between each other. Based on the genetic analysis, the primary mini-core strains were constructed with progressive sampling method of the smallest genetic distance. The mini-core germplasm collection included 4 strains (strain 2, 5, 7 and 11). Our findings will provide a scientific fundament for facilitating parent selection for broadening genetic base, accelerating the genetic breeding, identification of cultivated strains and the development of bioactive products from this commercially important medicinal mushroom.

Crepidotus yuanchui sp. nov. and C. caspari found in subalpine areas of China.

Only a few Crepidotus species have been previously reported from subalpine areas of China. Members of Crepidotus possessing an orange-yellow pileus are rare in China as well. Here, we describe Crepidotus yuanchui, a new species characterized by an orange-yellow pileus, ovoid basidiospores, and abundant cylindric to narrowly utriform cheilocystidia. This species is widely distributed above 2000 m asl in Yunnan Province. In addition, C. caspari, which is a distinct species based on its combined characteristics of smooth basidiospores and clamp connections, is newly recorded and detailed from subalpine China. The results of phylogenetic analyses of ITS + nLSU sequences based on maximum likelihood and Bayesian inference methods support the recognition of these two species. Photographs, descriptions, line drawings, and comparisons of related species are provided.

Four new species of Mycenasect.Calodontes (Agaricales, Mycenaceae) from northeast China.

Species of Mycenasect.Calodontes are representative of the Mycena genus as a whole and are easily recognised by the pinkish, reddish, purplish to brownish pileus and larger basidiomata. Furthermore, the colour of the pileus in the species of sect. Calodontes often has a transition or changes in different stages and the combination of the colour of the pileus with cystidia and basidiospores can be used to recognise taxa within this section. To date, 19 species of Mycenasect.Calodontes have been reported worldwide. Including our recent description of M.yuezhuoi, five species of sect. Calodontes have been recorded in China. During examination of specimens collected in coniferous forests or mixed broadleaf-conifer forests in temperate regions of China, additional taxa assigned to sect. Calodontes were identified. Four new species are recognised, based mostly on characters of the pileus and cystidia. Phylogenetic analysis of sequence data from multiple DNA regions (ITS + rpb1 + tef1) supported the morphological evidence. Here, we propose M.polycystidiata, M.rufobrunnea, M.shengshanensis and M.subulata as new species in Mycenasect.Calodontes. Morphological descriptions, line drawings, habitat photos and comparisons with closely-related taxa are provided. A key to the 23 known species of sect. Calodontes is presented.

Preliminary Studies on the Effects of Oyster Mushroom Spherical Virus China Strain on the Mycelial Growth and Fruiting Body Yield of the Edible Mushroom Pleurotus ostreatus.

Oyster mushroom spherical virus (OMSV) is a positive-sense single-stranded RNA mycovirus which is associated with a devastating oyster mushroom die-back disease. However, little is known about its diversity, and the effects of OMSV infection on its fungal host are not well understood. In this study, we determined the nearly complete nucleotide sequence of OMSV isolated from cultivated oyster mushrooms in China. Sequence analysis suggested that the virus represents a new strain of OMSV (referred to here as OMSV-Ch). A GenBank BLAST search of the genomic sequences demonstrated that the OMSV-Ch had the highest identity (74.9%) with the OMSV from Korea (OMSV-Kr). At the amino acid-sequence level, these two strains shared 84.1% identity in putative replication protein (RP) and 94.1% identity in coat protein (CP). Phylogenetic analysis based on RP showed that OMSV-Ch clustered with OMSV-Kr, closely related to Tymoviridae. Phylogenetic analysis based on both the RP and CP showed that OMSV had a distant clade relationship with tymoviruses, marafiviruses, and maculaviruses. We obtained the OMSV-Ch-free Pleurotus ostreatus strain via single hyphal tip cultures combined with high-temperature treatment. Preliminary studies indicate that OMSV-Ch can significantly inhibit mycelial growth, cause malformations of the fruiting bodies, and reduce the yield of P. ostreatus. Co-cultivation resulted in horizontal transmission of the OMSV-Ch to a virus-cured strain. The findings of our study contribute to the prevention and control of mycoviral diseases in the future.

Taxonomic studies of bluish Mycena (Mycenaceae, Agaricales) with two new species from northern China.

Bluish Mycena are rare, but constitute a taxonomically complex group. A total of eight bluish species in four sections have previously been reported from North America, Europe, Oceania and Asia. Two species with a blue pileus, collected in China during our taxonomic study of Mycena s.l., are described here as new to science: Mycenacaeruleogrisea sp. nov. and M.caeruleomarginata sp. nov. Detailed descriptions, line drawings and a morphological comparison with closely-related species, especially herbarium specimens of M.subcaerulea from the USA, are provided. The results of Bayesian Inference and Maximum Likelihood phylogenetic analyses of a dataset of 96 nuclear rDNA ITS and 20 nLSU sequences of 43 Mycena species are also presented. The morphological data and the results of the phylogenetic analyses support the introduction of M.caeruleogrisea and M.caeruleomarginata as new species. A taxonomic key to bluish Mycena species of sections Amictae, Cyanocephalae, Sacchariferae and Viscipelles is provided.