• The Plant Pathology Journal
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• v.29 no.4
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• pp.460-464
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• 2013

dsRNA was found in malformed cultures of Lentinula edodes strain FMRI0339, one of the three most popular sawdust cultivated commercial strains of shiitake, and was also found in healthy-looking fruiting bodies and actively growing mycelia. Cloning of the partial genome of the dsRNA revealed the presence of the RdRp sequence of a novel L. edodes mycovirus (LeV), and sequence comparison of the cloned amplicon showed identical sequences sequence to known RNA-dependent RNA polymerase genes of LeV found in strain HKA. The meiotic stability of dsRNA was examined by measuring the ratio of the presence of dsRNA among sexual monokaryotic progeny. More than 40% of the monokaryotic progeny still contained the dsRNA, indicating the persistence of dsRNA during sexual reproduction. Comparing the mycelia growth of monokaryotic progeny suggested that there appeared to be a tendency toward a lower frequency of virus incidence in actively growing progeny.

• Journal of Mushroom
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• v.10 no.3
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• pp.101-108
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• 2012

Pleurotus ostreatus 'Miso' is a mutant strain showing white color in pileus from the known parent strain 'Wonhyeong 1'. Shape and several other characters also vary with culture conditions. Mating experiments were performed to understand interstrain mating relationship using monokaryons of the parent and the mutant strains. All monokaryons were grown from single spores isolated from freshly collected fruit bodies. Pairings were performed in 90 mm petri dishes on PDA. They were allowed to grow at 25 until two fronts of the advancing mycelia met and developed a conspicuous contact zone. The contact zone and the outer edges of paired colonies on each plate were examined for clamp connections. The parent and the mutant resulted in tetrapolar incompatibility in intrastrain crosses. In interstrain crosses, each monokaryotic tester strain of the parent strain was out-crossed to monokaryotic tester strains of the mutant. As a result of these crosses it was found that both strains share the same A and B incompatibility factors yielding 25% compatibility.

• Mycobiology
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• v.45 no.4
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• pp.379-384
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• 2017

In mating of Lentinula edodes, dikaryotic strains generated from certain monokaryotic strains such as the B2 used in this study tend to show better quality of fruiting bodies regardless of the mated monokaryotic strains. Unlike B2, dikaryotic strains generated from B16 generally show low yields, with deformed or underdeveloped fruiting bodies. This indicates that the two nuclei in the cytoplasm do not contribute equally to the physiology of dikaryotic L. edodes, suggesting an expression bias in the allelic genes of the two nuclei. To understand the role of each nucleus in dikaryotic strains, we investigated single nucleotide polymorphisms (SNPs) in laccase genes of monokaryotic strains to reveal nuclear origin of the expressed mRNAs in dikaryotic strain. We performed reverse transcription PCR (RT-PCR) analysis using total RNAs extracted from dikaryotic strains (A5B2, A18B2, and A2B16) as well as from compatible monokaryotic strains (A5, A18, and B2 for A5B2 and A18B2; A2 and B16 for A2B16). RT-PCR results revealed that Lcc1, Lcc2, Lcc4, Lcc7, and Lcc10 were the mainly expressed laccase genes in the L. edodes genome. To determine the nuclear origin of these laccase genes, the genomic DNA sequences in monokaryotic strains were analyzed, thereby revealing five SNPs in Lcc4 and two in Lcc7. Subsequent sequence analysis of laccase mRNAs expressed in dikaryotic strains revealed that these were almost exclusively expressed from B2-originated nuclei in A5B2 and A18B2 whereas B16 nucleus did not contribute to laccase expression in A2B16 strain. This suggests that B2 nucleus dominates the expression of allelic genes, thereby governing the physiology of dikaryons.

• Mycobiology
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• v.43 no.1
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• pp.81-86
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• 2015

To promote the selection of promising monokaryotic strains of button mushroom (Agaricus bisporus) during breeding, 61 progeny strains derived from basidiospores of two different lines of dikaryotic parental strains, ASI1038 and ASI1346, were analyzed by nucleotide sequencing of the intergenic spacer I (IGS I) region in their rDNA and by extracellular enzyme assays. Nineteen different sizes of IGS I, which ranged from 1,301 to 1,348 bp, were present among twenty ASI1346-derived progeny strains, while 15 different sizes of IGS I, which ranged from 700 to 1,347 bp, were present among twenty ASI1038-derived progeny strains. Phylogenetic analysis of the IGS sequences revealed that different clades were present in both the ASI10388- and ASI1346-derived progeny strains. Plating assays of seven kinds of extracellular enzymes (${\beta}$-glucosidase, avicelase, CM-cellulase, amylase, pectinase, xylanase, and protease) also revealed apparent variation in the ability to produce extracellular enzymes among the 40 tested progeny strains from both parental A. bisporus strains. Overall, this study demonstrates that characterization of IGS I regions and extracellular enzymes is useful for the assessment of the substrate-degrading ability and heterogenicity of A. bisporus monokaryotic strains.

• 한국균학회소식:학술대회논문집
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• 2015.11a
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• pp.37-37
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• 2015

dsRNA was found in malformed cultures of Lentinula edodes strain FMRI0339, one of the three most popular sawdust cultivated commercial strains of shiitake, and was also found in healthy-looking fruiting bodies and actively growing mycelia. Cloning of the partial genome of the dsRNA revealed the presence of the RdRp sequence of a novel L. edodes mycovirus (LeV), and sequence comparison of the cloned amplicon showed an identical sequence to known RdRp genes of LeV found in strain HKA. The meiotic stability of dsRNA was examined by measuring the ratio of the presence of dsRNA among sexual monokaryotic progeny. More than 40% of the monokaryotic progeny still contained the dsRNA, indicating the persistence of dsRNA during sexual reproduction. Comparing the mycelia growth of monokaryotic progeny suggested that, although variations in the growth rate existed among progeny and virus infection was observed in highly actively growing progeny, there appeared to be a tendency toward a lower frequency of virus incidence in actively growing progeny. This study attempted to cure the edible mushroom L. edodes strain FMRI0339 of the L. edodes mycovirus (LeV) in order to obtain an isogenic virus-free fungal strain as well as a virus-infected strain for comparison. Mycelial fragmentation, followed by being spread on a plate with serial dilutions resulted in a virus-free colony. Viral absence was confirmed with gel electrophoresis after dsRNA-specific virus purification, Northern blot analysis, and PCR using reverse transcriptase (RT-PCR). Once cured, all of fungal cultures remained virus-free over the next two years. Interestingly, the viral titer of LeV varied depending on the culture condition. The titer from the plate culture showed at least a 20-fold higher concentration than that grown in the liquid culture. However, the reduced virus titer in the liquid culture was recovered by transferring the mycelia to a plate containing the same medium. In addition, oxygen-depleted culture conditions resulted in a significant decrease of viral concentration, but not to the extent seen in the submerged liquid culture. Although no $discernable phenotypic changes in colony morphology were observed, virus-cured strains showed significantly higher growth rates and mycelial mass than virus-infected strains. We were also explored effects of LeV on fruiting body formation and mushroom yield. The fruiting body formation yield of virus-free L. edodes was larger than virus-infected L. edodes. These results indicate that LeV infection has a deleterious effect on mycelial growth and fruiting body formation. In addition, we have been investigated host-parasite interaction between L. edodes and its mycovirus interaction to study viral mechanism by establishment of proteomics.

• Mycobiology
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• v.49 no.1
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• pp.86-88
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• 2021

The monokaryotic strain, Schizophyllum commune strain IUM1114-SS01, was generated from a basidiospore of dikaryotic parental strain IUM1114. It even showed the decolorizing activities for several textile dyes much better than its parental strain. Based on the results of a single-molecule real-time sequencing technology, we present the draft genome of S. commune IUM1114-SS01, comprising 41.1 Mb with GC contents of the genome were 57.44%. Among 13,380 protein-coding genes, 534 genes are carbon hydrate-active enzyme coding genes.

• Mycobiology
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• v.46 no.4
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• pp.407-415
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• 2018

Pheromone (PHB)-receptor (RCB) interaction in the mating pheromone response pathway of Lentinula edodes was investigated using synthetic PHBs. Functionality of the C-terminally carboxymethylated synthetic PHBs was demonstrated by concentration-dependent induction of a mating-related gene (znf2) expression and by pseudoclamp formation in a monokaryotic strain S1-11 of L. edodes. Treatment with synthetic PHBs activated the expression of homeodomain genes (HDs) residing in the A mating type locus, and of A-regulated genes, including znf2, clp1, and priA, as well as genes in the B mating type locus, including pheromone (phb) and receptor (rcb) genes. The synthetic PHBs failed to discriminate self from non-self RCBs. PHBs of the B4 mating type (B4 PHBs) were able to activate the mating pheromone response pathway in both monokaryotic S1-11 and S1-13 strains, whose B mating types were B4 (self) and B12 (non-self), respectively. The same was true for B12 PHBs in the B4 (non-self) and B12 (self) mating types. The synthetic PHBs also promoted the mating of two monokaryotic strains carrying B4-common incompatible mating types ($A5B4{\times}A1B4$). However, the dikaryon generated by this process exhibited abnormally high content of hyphal branching and frequent clamp connections and, more importantly, was found to be genetically unstable due to overexpression of mating-related genes such as clp1. Although synthetic PHBs were unable to discriminate self from non-self RCBs, they showed a higher affinity for non-self RCBs, through which the mating pheromone response pathway in non-self cells may be preferentially activated.

• The Korean Journal of Mycology
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• v.49 no.4
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• pp.487-495
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• 2021

Lentinula edodes is a tetrapolar basidiomycete and its mating type is determined by two unlinked genetic loci, A and B. Theoretically, one dikaryotic strain could produce basidiospores with four different mating types in a 1:1:1:1 ratio. Previous studies have described the skewed segregation ratio of mating types among basidiospores of L. edodes. However, they were based only on morphological characteristics, such as clamp connection, to determine mating types. To clarify whether the segregation distortion of mating types is a general phenomenon in L. edodes, we analyzed the mating types of basidiospores obtained from three cultivars of L. edodes using recently developed DNA markers. We found that the skewed segregation of mating types was strain-specific, as reported previously. Among the three cultivars, one cultivar showed balanced segregation, while the other two displayed distorted segregation. We also examined the relationship between mating type and mycelial growth rate of monokaryons derived from each basidiospore. It was found that the monokaryotic mycelial growth rate was related to the A mating type but not to the B mating type. Therefore, homeodomain transcription factor genes that reside on the A locus or other genes linked to the A locus affect the growth rate of monokaryotic mycelia. Considering the importance of mating types in mushroom breeding, this study is informative for establishing an efficient breeding strategy as well as for understanding the mechanism of monokaryotic mycelial growth.

• The Korean Journal of Mycology
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• v.50 no.4
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• pp.263-274
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• 2022

Lentinula edodes is an important commercial mushroom and there have been several reports of viral infections in L. edodes. Two mycoviruses (LeV-HKB and LeNSRV1) were detected in Sanbaekhyang (NIFoS 2778) and Taehyanggo (NIFoS 4317), the sawdust-cultivated commercial strains. The vertical transmission rates of the viruses were investigated by detecting the viruses in 80 monokaryotic strains derived from basidiospores isolated from the fruiting bodies of each strain. Most of the monokaryotic strains were infected with the virus and the two viruses showed different levels of meiotic stability, with LeV-HKB showing higher meiotic stability than LeNSRV1. Therefore, it seems that the vertical transmission mechanism of mycoviruses is different depending on the virus species. We also examined the mycelial growth rate of the monokaryotic strains and compared the growth rate according to virus infection status. Although there was no statistically significant correlation between viral infection and mycelial growth rate, we found that the average growth rate was reduced by additional virus infection. We expect our data to contribute to a greater understanding of the mechanism of the vertical transmission of mycoviruses, and promoting breeding using virus-free monokaryotic strains.

• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.42-42
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• 2014

Mating of tetrapolar mushrooms is regulated by to chromosomal loci, A and B. A locus contains A gene that expresses a homeodomain protein whereas B locus contains multiple pheromones and receptor genes. In order to characterize the mating loci in Korean cultivated strains of Lentinula edodes, one hundred monokaryotic myclelia were isolated from the basidiospores of cultivated strains, including Cham-A-Ram, Sanjo701, and Sanjo707. Both mating loci were amplified using primer sets targeting conserved sequence regions for homeodomain (HD), pheromone, and receptor genes. Subsequent sequence analysis revealed that the Korean strains contained significant variations in the homeodomain of A locus, even within the same A1 or A2 mating type. Similarly, B locus was also highly diversified in the sequences of pheromones and receptors as well as gene organization. These results enabled us to design mating type-specific probes which can distinguish mating type of each strain. The specificity was confirmed by between intra- and inter-strain mating experiment.