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Mycelial growth of wild-type and degenerate dikaryons of F. velutipes. (A) Morphology of the mycelia of the wild-type (left) and degenerate strains (right) that were grown on MCM agar for 7 d. (B) Growth rates of the wild-type and degenerate strains were determined based on the diameter of the mycelia grown at 25°C. The error bars represent the mean standard deviations of triplicate samples.
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Flammulina velutipes is one of the major edible mushrooms in the world. Recently, abnormalities that have a negative impact on crop production have been reported in this mushroom. These symptoms include slow vegetative growth, a compact mycelial mat, and few or even no fruiting bodies. The morphologies and fruiting capabilities of monokaryons of wi...
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Flammulina velutipes, one of the most popular mushroom species in the world, has been recognized as a useful model system to study the biochemical and physiological aspects of the formation and elongation of fruit body. However, few reports have been published on the regulation of fruiting body formation in F. velutipes at the molecular level. In t...
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Citations
... For example, Yin et al. [177] observed strain degeneration from the third generation, displaying incomplete growth by the fourth. Similarly, Kim et al. [178] reported symptoms of degraded strains during continuous subculturing, such as slowed vegetative mycelial growth and less-tight mycelial pads. ...
... For example, Yin et al. [177] observed strain degeneration from the third generation, displaying incomplete growth by the fourth. Similarly, Kim et al. [178] reported symptoms of degraded strains during continuous subculturing, such as slowed vegetative mycelial growth and less-tight mycelial pads. Inducing mushroom mycelium to produce fruiting bodies completes the fungal life cycle, generating complex mycelium structures and spores with the original genetic information (Zhao et al. [174]). ...
Mycelium-based green composites (MBCs) represent an eco-friendly material innovation with vast potential across diverse applications. This paper provides a thorough review of the factors influencing the production and properties of MBCs, with a particular focus on interdisciplinary collaboration and long-term sustainability goals. It delves into critical aspects such as fungal species selection, substrate type selection, substrate preparation, optimal conditions, dehydrating methods, post-processing techniques, mold design, sterilization processes, cost comparison, key recommendations , and other necessary factors. Regarding fungal species selection, the paper highlights the significance of considering factors like mycelium species, decay type, hyphal network systems, growth rate, and bonding properties in ensuring the safety and suitability of MBCs fabrication. Substrate type selection is discussed, emphasizing the importance of chemical characteristics such as cellulose, hemicellulose, lignin content, pH, organic carbon, total nitrogen, and the C: N ratio in determining mycelium growth and MBC properties. Substrate preparation methods, optimal growth conditions, and post-processing techniques are thoroughly examined, along with their impacts on MBCs quality and performance. Moreover, the paper discusses the importance of designing molds and implementing effective sterilization processes to ensure clean environments for mycelium growth. It also evaluates the costs associated with MBCs production compared to traditional materials , highlighting potential cost savings and economic advantages. Additionally, the paper provides key recommendations and precautions for improving MBC properties, including addressing fungal strain degeneration, encouraging research collaboration, establishing biosecurity protocols, ensuring regulatory compliance, optimizing storage conditions, implementing waste management practices, conducting life cycle assessments, and suggesting parameters for desirable MBC properties. Overall, this review offers valuable insights into the complex interplay of factors influencing MBCs production and provides guidance for optimizing processes to achieve sustainable, high-quality composites for diverse applications.
... successor degenerated strains of C. militaris suffer from slow growth rates, defective fruiting body formation and pigment production, low mushroom production, and deformed mushrooms. Kim et al. (2014) reported that the degenerate strain of Flammulina velutipes exhibited slow hyphae growth, tight hyphal pads, and little or no fruiting bodies. The fruiting body of V. volvacea is the organized mycelium, which has strong regenerative ability. ...
The fungal fruiting body is the organized mycelium. Tissue isolation and mycelium succession are common methods of fungal species purification and rejuvenation in the production of edible mushrooms. However, repeated succession increases strain degeneration. In this study, we examined the effect of repeated tissue isolation from Volvariella volvacea fruitbodies on the occurrence of degeneration. The results showed that less than four times in succession improved production capacity, however, after 12 successions, the traits indicating strain degeneration were apparent. For instance, the density of aerophytic hyphae, hyphal growth rate and hyphal biomass were gradually reduced, while the hyphae branching was increased. Also, other degenerative traits such as prolonged production cycles and decreased biological efficiency became evident. In particular, after 19 successions, the strain degeneration became so severe no fruiting bodies were produces anymore. Meanwhile, with the increase in successions, the antioxidant enzyme activity decreased, reactive oxygen species (ROS) increased, the number of nuclei decreased, and the mitochondrial membrane potential decreased along with morphological changes in the mitochondria. This study showed that repeated tissue isolation increased oxidative damage in the succession strain due to the accumulation of ROS, causing cellular senescence, in turn, degeneration in V. volvacea strain.
... In the case of Yin et al. (2017), it was shown that strains began to degenerate at the third generation, with their fruiting bodies displaying incomplete growth on the fourth one. Finally Kim et al. (2014), reported slow vegetative growth, tight mycelial pads, and few or no fruiting bodies as some of the symptoms of degraded F. velutipes strains. In line with the above, and particularly the findings of , this study showed that the density of aerial mycelia, along with their growth rate and biomass, gradually decreased as the degeneration level increased (Figure 1). ...
Strain degradation is a common problem in many artificially-cultivated edible mushrooms. As a fungus with poor tolerance to low-temperature, Volvariella volvacea cannot delay its degradation by long-term low temperature storage like other fungi, so its degradation is particularly severe, which hinders industrial applications. Periodic mycelial subculture is a common storage method for V. volvacea, but excessive subculturing can also lead to strain degeneration. After 20 months of continuous subculturing every 3 days, V. volvacea strains S1–S20 were obtained, and their characteristics throughout the subculture process were analyzed. With increasing number of subculture, the growth rate, mycelial biomass, the number of fruiting bodies and biological efficiency gradually decreased while the production cycle and the time to primordium formation was lengthened. Strains S13–S20, obtained after 13–20 months of mycelial subculturing, also lacked the ability to produce fruiting bodies during cultivation experiments. Determination of reactive oxygen species (ROS) content as well as enzyme activity showed that decreased lignocellulase activity, along with excessive accumulation of ROS, was concomitant with the subculture-associated degeneration of V. volvacea. Reverse transcription polymerase chain reaction (RT-PCR) was eventually used to analyze the gene expression for lignocellulase and antioxidant enzymes in subcultured V. volvacea strains, with the results found to be consistent with prior observations regarding enzyme activities. These findings could form the basis of further studies on the degeneration mechanism of V. volvacea and other fungi.
... Degeneration also causes significant economic losses for F. velutipes (Magae et al. 2005). Degeneration of F. velutipes results in slow vegetative growth, a compact mycelial mat, and few or even no fruiting bodies ( Kim et al. 2014). ...
As a highly valued fungus, Cordyceps militaris has been widely used all over the world. Although the wild resources of C. militaris are limited, the fruiting bodies of C. militaris have been successfully cultivated on a large-scale. However, the high-frequency degeneration of C. militaris during subculture and preservation seriously limits the development of the C. militaris industry. How to solve the degeneration of C. militaris has become an unsolved bottleneck problem throughout the whole Cordyceps industry. The aim of this review is to illustrate the phenotypic changes after the degeneration of C. militaris, focusing on the causes (including environmental factors and genetic variation) of C. militaris degeneration. Moreover, genetic variation is the root cause of the degeneration of C. militaris strains. Measures to prevent the degeneration of C. militaris are also discussed in this review. This paper will increase understanding of the degeneration mechanism of C. militaris, provide a reference for solving the degeneration problem of C. militaris, and lay a foundation for promoting the sustainable development of C. militaris.
... However, the excessive subculturing of edible mushrooms may cause degeneration Yin et al., 2017). Degenerated edible mushrooms are characterized by slim, fragile, and slow-growing mycelia (Magae et al., 2005;Kim et al., 2014). ...
... They were not detected in the normal strains in fruiting-impaired degenerative isolates. Kim et al. (2014) reported that the symptoms of degenerated F. velutipes strains include slow vegetative growth, a compact mycelial mat, and few, or even no, fruiting bodies. Yin et al. (2017) artificially cultured the entomopathogenic mushroom Cordyceps militaris for six generations and observed changes during fruiting-body growth. ...
... In this study, there was no significant difference in the mycelial biomass between M1 and M0 (P > 0.05), but there were significant differences in the mycelial biomasses between M2-M6 and M0 (P < 0.05) (Figure 2). Thus, the mycelial biomasses of degenerated strains decreased continuously as the subculturing continued, which might result in unsatisfying, and even a lack of, output from degenerated strains (Kim et al., 2014; Chen et al., 2017;Yin et al., 2017). Moreover, we discovered a similar trend between the mycelial growth rate and mycelial biomass as the subculturing continued. ...
Volvariella volvacea is a typical edible Basidiomycete with a high-temperature tolerance. It has a strong fibrinolysis capability and consumes abundant agricultural wastes. In agricultural cultivation, mycelial subculturing has been adopted, leading to serious strain degeneration. In this study, continuous mycelial subculturing of the common V. volvacea strain V971 (original strain recorded as M0) was performed in potato dextrose agar (PDA) medium. One generation of the strain was preserved every 3 months (90 days); thus, six generations of degenerated strains (M1–M6) were obtained after 18 months of mycelial subculturing. The original and degenerated strains were preserved in sterile paraffin liquid at room temperature (18–25°C). The biological traits and nutrients of M0 and M1–M6 were studied. The mycelial growth rate and biomass initially increased and then decreased as the degeneration progressed, reaching minimum levels of 0.041 ± 0.001 cm/h and 1.82 ± 0.25 g, respectively, at M6. Additionally, the polysaccharide, protein, polyphenol, flavone, total amino acid, and total mineral element contents of the strains decreased continuously, reaching minimum levels of 30.12 ± 3.12 g/100 g, 26.42 ± 2.1 g/100 g, 1.08 ± 0.05 g/100 g, 4.23 ± 0.21 g/100 g, 12.51 mg/g, and 398.05 mg/kg, respectively, at M6. The decolorization capability of V. volvacea in liquid medium supplemented with bromothymol blue and lactose reflected the degree of strain degeneration, with the capability weakening as the degeneration intensified. These results are highly significant for V. volvacea production. The mycelial characteristics during subculture-associated degeneration were described and provide an early identification method for V. volvacea’s degeneration.
... Some recent studies have reported the use of SCAR markers for edible fungi. For example, they have been used in studies on the color of the fruiting bodies of Agaricus bisporus [12], Flammulina velutipes [13] and Hypsizygus marmoreus [14], the degeneration of Volvariella volvacea strains [15] and F. velutipes [16], mushroom disease in Auricularia polytricha [17], and the mating types of edible fungi [18,19]. These markers have also been used to screen for various traits during breeding. ...
... The (Table 1). Single 522-bp band was amplified by SCL-18 primer in lane 1, 3,6,9,13,16,18, and 20, corresponding to strains with cluster-type fruiting body pattern (Table 1). M: 1500-bp ladder marker. ...
The fruiting body pattern is an important agronomic trait of the edible fungus Auricularia auricula-judae, and an important breeding target. There are two types of fruiting body pattern: the cluster type and the chrysanthemum type. We identified the fruiting body pattern of 26 test strains, and then constructed two different near-isogenic pools. Then, we developed sequence characterized amplified region (SCAR) molecular markers associated with the fruiting body pattern based on sequence-related amplified polymorphism (SRAP) markers. Ten different bands (189–522 bp) were amplified using 153 pairs of SRAP primers. The SCAR marker “SCL-18” consisted of a single 522-bp band amplified from the cluster-type strains, but not the chrysanthemum strains. This SCAR marker was closely associated with the cluster-type fruiting body trait of A. auricula-judae. These results lay the foundation for further research to locate and clone genes controlling the fruiting body pattern of A. auricula-judae.
... due to green conidiation areas (Ansari and Butt 2011;Li et al. 2008;Ryan et al. 2002;Wang et al. 2005). Sectorisation is by no means exclusively of Metarhizium spp., for instance in edible mushrooms this is a common problem that causes important economic losses, since sectorised mycelia produce low fruiting bodies yields (Kim et al. 2014b). The use of spontaneous sector-formation strains is not recommended due to its commonly irreversible nature that leads to a reduction in conidial yields; also, poor quality may occur in the final conidial batch. ...
Demand for biopesticides is growing due to the increase of areas under integrated pest management worldwide. Conidia from entomopathogenic fungi play a major role as infective units in the current market of biopesticides. Success in a massive production of fungal conidia include the use of proper long-term conservation microbial methods, aimed at preserving the phenotypic traits of the strains. The development of suitable inoculants should also be considered since that favours a rapid germination and invasiveness of the substrate in solid state cultures (SSC). After the selection of a suitable fungal strain, proven optimization approaches for SSC mainly include the combination of substrates, moisture, texturizers, aeration and moderate stress to induce conidiation. Nonetheless, during storage and upon application in open fields, conidia either as free propagules or imbibed in formulations are subjected to stress due to abiotic factors, then quality should be preserved to resist such harsh conditions. All of these topics are analysed in this report.
... The unicellular, uninucleate, haploid asexual spores (oidia) of C. cinerea ( Fig. 12.2) for example allow an efficient protoplast transformation procedure and make C. cinerea to the champion filamentous fungus in genetic transformation with several hundreds of transformants obtained per mg DNA (Binninger et al. 1987;Granado et al. 1997;Dörnte and Kües 2012). Uninucleate spores on dikaryons permit further in various species to obtain cells with individual component nuclei, for example for karyotyping and breeding purposes (Walser et al. 2001;Tanesaka et al. 2012;Kim et al. 2014). Asexual spores can serve in replica plating of fungal colonies for efficient genetic screenings (Polak et al. 1997b). ...
Production of mitotic spores has been reported for various species of the Agaricomycetes but is generally rather neglected and the extent of asexual sporulation in this class of Basidiomycetes is unknown. The typical life cycle of Agaricomycetes comprises of two alternate mycelial stages, the sterile monokaryon and the fertile dikaryon. The monokaryon contains only one type of haploid nuclei. The dikaryon is formed by mating of two compatible monokaryons and has two distinct haploid nuclei in its hyphal cells, each one per parental monokaryon. Both types of mycelia may produce asexual spores but species differ in whether mitospores are formed at the monokaryon, at the dikaryon, at both or at none. Mitospores produced on the dikaryon might be homokaryotic or heterokaryotic. Here, we present an overview on species of the Agaricomycetes and their spores. Types of sporulation include thallic spore formation (arthroconidia), blastic sporulation (blastoconidia) and intracellular production of thick-walled chlamydospores. Where known, we discuss functions of spores and regulation of mitospore production.
As a highly valued fungus, Cordyceps militaris has been widely used all over the world. Although the wild resources of C. militaris are limited, the fruiting bodies of C. militaris have been successfully cultivated on a large-scale. However, the high-frequency degeneration of C. militaris during subculture and preservation seriously limits the development of the C. militaris industry. How to solve the degeneration of C. militaris has become an unsolved bottleneck problem throughout the whole Cordyceps industry. The aim of this review is to illustrate the phenotypic changes after the degeneration of C. militaris, focusing on the causes (including environmental factors and genetic variation) of C. militaris degeneration. Moreover, genetic variation is the root cause of the degeneration of C. militaris strains. Measures to prevent the degeneration of C. militaris are also discussed in this review. This paper will increase understanding of the degeneration mechanism of C. militaris, provide a reference for solving the degeneration problem of C. militaris, and lay a foundation for promoting the sustainable development of C. militaris.
