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Flammulina filiformis is one of the widely produced edible fungi worldwide. It is rich in γ-aminobutyric acid (GABA), a non-protein amino acid with important physiological functions in humans. To investigate the functions of key genes in the GABA metabolic pathway of F. filiformis, we isolated the monokaryon Fv-HL23-1 from the factory-cultivated F. filiformis strain Fv-HL23 and then sequenced and assembled the genome using the PacBio Sequel and Illumina NovaSeq sequencing platforms. The results showed that the genome comprised 140 scaffolds with a total length of 40.96 Mb, a GC content of 49.62%, an N50 of 917,125 bp, and 14,256 protein-coding genes. Phylogenetic analysis based on the whole genome revealed a close evolutionary relationship of Fv-HL23-1 with Armillaria mellea, Lentinula edodes, and Schizophyllum commune. A total of 589 carbohydrate-active enzymes were identified in the genome of Fv-HL23-1, suggesting its strong lignocellulose degradation ability, and 108 CYP450 gene family members were identified, suggesting important functions such as resistance to stress, secondary metabolite synthesis, and growth and development. The F. filiformis proteins glutamate decarboxylase 1 (Ff-GAD1) and glutamate decarboxylase 2 (Ff-GAD2), which may be responsible for GABA synthesis, were identified by protein alignment. Molecular docking analysis showed that Ff-GAD2 may have better catalytic activity than Ff-GAD1. To verify the function of Ff-gad2, its heterologous expression in the mycelia of the mononuclear Hypsizigus marmoreus was analyzed. Compared with wild type, the GABA content of mycelia was increased by 85.40–283.90%, the growth rate was increased by 9.39 ± 2.35%, and the fresh weight was increased by 18.44 ± 7.57%. Ff-GAD2 may play a catalytic role in GABA synthesis. In addition, the expression of the full-length Ff-gad2 gene was increased by 7.96 ± 1.39 times compared with the exon expression level in H. marmoreus mycelia, suggesting that the intron may contribute to the heterologous expression of Ff-GAD2. Based on whole-genome sequencing, we analyzed the enzyme system related to the important life activities of F. filiformis, focusing on the function of Ff-GAD, a key enzyme in the GABA synthesis pathway. The results lay a foundation for elucidating the GABA metabolism pathway of edible fungi and developing targeted breeding strategies for GABA-producing edible fungi. [ABSTRACT FROM AUTHOR]

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Abstract This study compared the pathogenicity of monokaryotic (monokaryon) and dikaryotic (dikaryon) mycelia of the oil palm pathogen Ganoderma boninense via metabolomics approach. Ethyl acetate crude extracts of monokaryon and dikaryon were analysed by liquid chromatography quadrupole/time-of-flight-mass spectrometry (LC-Q/TOF–MS) coupled with multivariate data analysis using MetaboAnalyst. The mummichog algorithm was also used to identify the functional activities of monokaryon and dikaryon without a priori identification of all their secondary metabolites. Results revealed that monokaryon produced lesser fungal metabolites than dikaryon, suggesting that monokaryon had a lower possibility of inducing plant infection. These findings were further supported by the identified functional activities. Monokaryon exhibits tyrosine, phenylalanine, and tryptophan metabolism, which are important for fungal growth and development and to produce toxin precursors. In contrast, dikaryon exhibits the metabolism of cysteine and methionine, arginine and proline, and phenylalanine, which are important for fungal growth, development, virulence, and pathogenicity. As such, monokaryon is rendered non-pathogenic as it produces growth metabolites and toxin precursors, whereas dikaryon is pathogenic as it produces metabolites that are involved in fungal growth and pathogenicity. The LC–MS-based metabolomics approach contributes significantly to our understanding of the pathogenesis of Ganoderma boninense, which is essential for disease management in oil palm plantations.

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This study compared the pathogenicity of monokaryotic (monokaryon) and dikaryotic (dikaryon) mycelia of the oil palm pathogen Ganoderma boninense via metabolomics approach. Ethyl acetate crude extracts of monokaryon and dikaryon were analysed by liquid chromatography quadrupole/time-of-flight-mass spectrometry (LC-Q/TOF–MS) coupled with multivariate data analysis using MetaboAnalyst. The mummichog algorithm was also used to identify the functional activities of monokaryon and dikaryon without a priori identification of all their secondary metabolites. Results revealed that monokaryon produced lesser fungal metabolites than dikaryon, suggesting that monokaryon had a lower possibility of inducing plant infection. These findings were further supported by the identified functional activities. Monokaryon exhibits tyrosine, phenylalanine, and tryptophan metabolism, which are important for fungal growth and development and to produce toxin precursors. In contrast, dikaryon exhibits the metabolism of cysteine and methionine, arginine and proline, and phenylalanine, which are important for fungal growth, development, virulence, and pathogenicity. As such, monokaryon is rendered non-pathogenic as it produces growth metabolites and toxin precursors, whereas dikaryon is pathogenic as it produces metabolites that are involved in fungal growth and pathogenicity. The LC–MS-based metabolomics approach contributes significantly to our understanding of the pathogenesis of Ganoderma boninense, which is essential for disease management in oil palm plantations. [ABSTRACT FROM AUTHOR]

Oudemansiella raphanipes, considered as a well-known culinary edible mushroom with a high content of natural bioactive substances, is widely cultivated in China with the commercial name Changgengu. However, due to the lack of genomic data, molecular and genetic study on O. raphanipes is rare. To obtain a comprehensive overview of genetic characteristics and enhance the value of O. raphanipes, two mating-compatible monokaryons isolated from the dikaryon were applied for de novo genome sequencing and assembly using Nanopore and /or Illumina sequencing platforms. One of the monokaryons, O. raphanipes CGG-A-s1, was annotated with 21,308 protein-coding genes, of which 56 were predicted to be involved in the biosynthesis of secondary metabolites such as terpene, type I PKS, NRPS, and siderophore. Phylogenetic and comparative analysis of multiple fungi genomes revealed a close evolutionary relationship between O. raphanipes and Mucidula mucid based on single-copy orthologous protein genes. Significant collinearity was detected between O. raphanipes and Flammulina velutipes on the synteny of inter-species genomes. 664 CAZyme genes in CGG-A-s1 were identified with GHs and AAs families significantly elevated when compared with the other 25 sequenced fungi, indicating a strong wood degradation ability. Furthermore, the mating type locus analysis revealed that CGG-A-s1 and CGG-A-s2 were conserved in the gene organization of the mating A locus but various in that of the mating B locus. The genome resource of O. raphanipes will provide new insights into its development of genetic studies and commercial production of high-quality varieties. [ABSTRACT FROM AUTHOR]

Flammulina filiformis, as one of the most popular edible fungi in East Asia, is produced in an industrialized and standardized way. However, its monotonous variety and product convergence have seriously restricted the development of the industry. In this study, 11 cultivated strains and 13 wild strains of F. filiformis were collected from multiple regions of China and Japan and were performed genome sequencing. Together with genome data of six strains previously released, in total 23 dikaryons (formed by two monokaryons mating, can making fruiting body), 35 monokaryons (formed by protoplast-regenerating of dikaryon and isolating) were used for genetic diversity and population structure analysis based on the high-throughput genotyping. Firstly, a set of SNP markers with intrapopulation polymorphism including 849,987 bi-allelic SNPs were developed and basically covered all of 11 chromosomes with a high distribution density of 24.16 SNP markers per kb. The cultivated dikaryotic strains were divided into three subgroups, and their breeding history was made inferences, which is consistent with the available pedigree records. The wild dikaryotic strains were divided into two subgroups and showed varied contributions of genetic components with high genetic diversity. All the investigated dikaryons have a symmetric distribution pattern with their two constituent monokaryons in principal component analysis. Finally, we summarized the pedigree relationship diagram of F. filiformis main strains including six modules, and the genotypes of hybrids can be directly phased by the known parental allele according to it. This study provides a method to distinguish two sets of monokaryon haplotypes, and several valuable genetic resources of wild F. filiformis, and an effective strategy for guiding F. filiformis breeding based on the population structure and pedigree relationship in future. [ABSTRACT FROM AUTHOR]

In Coprinus comatus , we sampled and observed different maturity stages of basidium to find the possible causes of binucleate basidiospores by microscopy using the HCI-Giemsa and DAPI staining methods. In basidium, following karyogamy, a single nucleolus was observed. We found evidence suggesting post-meiotic mitosis following nuclear migration in the spores. Post-meiotic mitosis occurred in the basidiospores, resulting in four binucleate basidiospores. This indicates that the basidiospore is a monokaryon, and that C. comatus shows the same pattern of basidiospore formation as Coprinopsis cinerea. This type of nuclear behavior was defined as pattern D, one of six distinct patterns (pattern A–F) of nuclear behavior during basidiosporogenesis have been described for basidiomycetes by Campos and Costa in 2010. • In C. comatus , post-meiotic mitosis occurred in the basidiospores. • In C. comatus , we believe it is likely that the basidiospores are monokaryons. • We found an easy method to observe different stages of basidium. [ABSTRACT FROM AUTHOR]

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Copyright of Acta Edulis Fungi is the property of Acta Edulis Fungi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Identification of monokaryons and their mating types and discrimination of hybrid offspring are key steps for the crossbreeding of Pleurotus tuoliensis (Bailinggu). However, conventional crossbreeding methods are troublesome and time consuming. Using RNA-seq technology, we developed new expressed sequence tag-simple sequence repeat (EST-SSR) markers for Bailinggu to easily and rapidly identify monokaryons and their mating types, genetic diversity and hybrid offspring. We identified 1110 potential EST-based SSR loci from a newly-sequenced Bailinggu transcriptome and then randomly selected 100 EST-SSRs for further validation. Results showed that 39, 43 and 34 novel EST-SSR markers successfully identified monokaryons from their parent dikaryons, differentiated two different mating types and discriminated F¹ and F2 hybrid offspring, respectively. Furthermore, a total of 86 alleles were detected in 37 monokaryons using 18 highly informative EST-SSRs. The observed number of alleles per locus ranged from three to seven. Cluster analysis revealed that these monokaryons have a relatively high level of genetic diversity. Transfer rates of the EST-SSRs in the monokaryons of closely-related species Pleurotus eryngii var. ferulae and Pleurotus ostreatus were 72% and 64%, respectively. Therefore, our study provides new SSR markers and an efficient method to enhance the crossbreeding of Bailinggu and closely-related species. [ABSTRACT FROM AUTHOR]

Dichomitus squalens is a white-rot fungus that colonizes and grows mainly on softwood and is commonly found in the northern parts of Europe, North America, and Asia. We analyzed the genetic and physiological diversity of eight D. squalens monokaryons derived from a single dikaryon. In addition, an unrelated dikaryon and a newly established dikaryon from two of the studied monokaryons were included. Both growth and lignocellulose acting enzyme profiles were highly variable between the studied monokaryotic and dikaryotic strains, demonstrating a high level of diversity within the species. [ABSTRACT FROM AUTHOR]

Agrobacterium-mediated gene transfer (AMT) is extensively employed as a tool in fungal functional genomics and accordingly, in previous studies we used AMT on a dikaryotic strain of the ectomycorrhizal basidiomycete Laccaria bicolor. The interest in this fungus derives from its capacity to establish a symbiosis with tree roots, thereby playing a major role in nutrient cycling of forest ecosystems. The ectomycorrhizal symbiosis is a highly complex interaction involving many genes from both partners. To advance in the functional characterization of fungal genes, AMT was used on a monokaryotic L. bicolor. A collection of over 1200 transgenic strains was produced, of which 200 randomly selected strains were analyzed for their genomic T-DNA insertion patterns. By means of insertional mutagenesis, a number of transgenic strains were obtained displaying differential growth features. Moreover, mating with a compatible strain resulted in dikaryons that retained altered phenotypic features of the transgenic monokaryon. The analysis of the T-DNA integration pattern revealed mostly similar results to those reported in earlier studies, confirming the usefulness of AMT on different genetic backgrounds of L. bicolor. Taken together, our studies display the great versatility and potentiality of AMT as a tool for the genetic characterization of L. bicolor. [ABSTRACT FROM AUTHOR]

Wood decay fungi are considered to be dispersed by wind, but dispersal by animals may also be important, and more so in managed forests where dead wood is scarce. We investigated whether beetles could disperse spores of the keystone species Fomitopsis pinicola. Beetles were collected on sporocarps and newly felled spruce logs, a favourable habitat for spore deposition. Viable spores (and successful germination) of F. pinicola were detected by dikaryotization of monokaryotic bait mycelium from beetle samples. Viable spores were on the exoskeleton and in the faeces of all beetles collected from sporulating sporocarps. On fresh spruce logs, nine beetle species transported viable spores, of which several bore into the bark. Our results demonstrate that beetles can provide directed dispersal of wood decay fungi. Potentially, it could contribute to a higher persistence of some species in fragmented forests where spore deposition by wind on dead wood is less likely. [ABSTRACT FROM AUTHOR]

The aim of this study was to breed G . lucidum strains simultaneously rich in polysaccharides and triterpenes by mating of basidiospore monokaryons of two commercial cultivars, G . lucidum JC and AL. By incubation of freshly collected basidiospores, 31 monokaryons were isolated (19 from strain JC, and 12 from strain AC), and showed significant differences in mycelial growth and contents of polysaccharide and triterpene. Mating between the two strains yielded 83 instances of sexual compatibility. Of the hybrids isolated, sixteen ones that showed moderate and fast substrate colonization were evaluated in terms of fruiting. All the tested hybrids produced fruiting bodies but varied considerably in time to first harvest, productivity, yield distribution, and pileus shape and color. Significant differences in polysaccharide content (from 6.79 to 18.21 mg/g dry weight) and triterpene content (from 5.90 to 10.87 mg/g dry weight) were also observed among the hybrids. Notably, high concentrations of polysaccharides (16.63 mg/g dry weight) and triterpenes (10.50 mg/g dry weight) were both present in hybrid H-23, with satisfactory biological efficiency (19.41%). An antagonism test and random amplified polymorphic DNA (RAPD) analysis indicated that H-23 is a new hybrid strain. This hybrid may be suitable for use in commercial production of G . lucidum for manufacture of more effective health-promoting and medicinal products. To our knowledge, the present study is the first report on the development of new G . lucidum strains via mating by means of basidiospore-derived monokaryons. [ABSTRACT FROM AUTHOR]

In this study, three species of oyster mushroom ( Pleurotus osturatus, P. eryngii and P. cornucopia) were crossed together in order to aggregate benefit special attributes to the genotype (s). The monokaryon of each of these species was prepared. Then, the monokaryons of two species were placed at 5 mm distance from each other to produce dikaryon. The results showed that, from among 700 crosses, only the crosses of eryngii and osturatus monokaryons were grown toward each other and produced clamps (dikaryons). Four produced hybrids were noted H, H, H and H. The spans of produced hybrids were prepared; then, they were grown into sterile media and attributions of hybrids were studied. The results indicated that H hybrid was an appropriate hybrid in terms of the number of days until growing, number of days until the observation of the first pin and the days from planting to harvest. However, H was the best hybrid based on cap diameter, dry and fresh weight of fruit body, yield and biomass. It is expected that these interspecific hybrids employ for future oyster mushroom breeding programs. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Southern Agriculture is the property of Journal of Southern Agriculture and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Protoplast fusion between Pleurotus ostreatus and P. djamor was carried out by isolating protoplasts from 4-day-old monokaryotic mycelia cultured on malt extract broth. The mycelia were then agitated at 100 rpm for 2 h with 9 mg Lysing Enzyme (Sigma L-1412) in 1 ml osmotic stabilizer (0.6 M MgSO4·7H2O in 0.05 M sodium maleate buffer,pH 5). The freshly prepared protoplasts were then mixed and incubated in 40% PEG (polyethylene glycol 6,000)/0.05 M CaCl2·2H2O for 20 min at room temperature. All protoplasts were regenerated on Regeneration Medium for 7-12 days. There were 412 regenerated colonies detected but only two of them were selected as fusants by posessing clamp connections on their mycelia. The fusants were proved to be "hybrids" of P. ostreatus and P. djamor. Their mycelia were significantly faster in growth and larger in size than the parental strains. They showed bands common to their parents when esterase was used for isozyme studies. The fruiting bodies of the fusants also showed recombined characteristics of the parental strains.

Pleurotus citrinopileatus (yellow oyster mushroom) has an attractive shape and yellow colour but the fragile texture complicates packaging, and its strong aroma is unappealing to consumers. This study aimed to improve the characteristics and yield of P. citrinopileatus by interspecies mating between monokaryotic cultures of P. citrinopileatus and P. pulmonarius. Ten monokaryon cultures of the parental lines were crossed in all combinations to obtain hybrids. Eleven compatible mating pairs were obtained and cultivated to observe their sporophore morphology and yield. The selected hybrid, i.e. P1xC9, was beige in colour while hybrid P3xC8 was yellow in colour. Their sporophores had less offensive aroma, improved texture and higher yield. The DNA sequences of these hybrids were found to be in the same clade as the P. citrinopileatus parent with a bootstrap value of 99 %. High bootstrap values indicate high genetic homology between hybrids and the P. citrinopileatus parent. The biological efficiencies of these hybrids P1xC9 (70.97 %) and P3xC8 (52.14 %) were also higher than the P. citrinopileatus parent (35.63 %). Interspecies hybrids obtained by this mating technique can lead to better strains of mushrooms for genetic improvement of the Pleurotus species. [ABSTRACT FROM AUTHOR]

We document here that monosporous isolates of the ectomycorrhizal basidiomycete Tricholoma matsutake were initially uni- or bi-nucleate. During pure culture, however, many uninucleate isolates became multinucleate. While the parent strain had two patterns of single nucleotide polymorphisms (SNPs) within its single-copy DNA, 19 of 20 monosporous isolates exhibited one of the two parent SNPs, and an isolate that was binucleate upon germination had both, indicating the former were monokaryotic and the latter dikaryotic. Of those, two isolates carrying SNPs different from one another have been predominantly uninucleate for 9 years. These isolates may be useful in genetics/breeding of “matsutake” mushrooms. [ABSTRACT FROM AUTHOR]

Several hundred monokaryotic and new dikaryotic strains derived thereof were established from (+)-valencene tolerant Pleurotus species. When grouped according to their growth rate on agar plates and compared to the parental of Pleurotus sapidus 69, the slowly growing monokaryons converted (+)-valencene more efficiently to the grapefruit flavour compound (+)-nootkatone. The fast growing monokaryons and the slow × slow and the fast × fast dikaryotic crosses showed similar or inferior yields. Some slow × fast dikaryons, however, exceeded the biotransformation capability of the parental dikaryon significantly. The activity of the responsible enzyme, lipoxygenase, showed a weak correlation with the yields of (+)-nootkatone indicating that the determination of enzyme activity using the primary substrate linoleic acid may be misleading in predicting the biotransformation efficiency. This exploratory study indicated that a classical genetics approach resulted in altered and partly improved terpene transformation capability (plus 60%) and lipoxygenase activity of the strains. [ABSTRACT FROM AUTHOR]

[Objective] This study aimed to analyze genetic differences among Flammulina velutipes monokaryon strains. [Method] Twenty F1 monokaryon strains (W1 - W20) of F. velutipes were separated with conventional dilution method. Fifteen SCoT primers and nine ISSR primers were screened. According to amplification results, genetic similarity coefficients among various strains were calculated using NTsys 2.10e analysis software for cluster analysis. [Result] Six primers could be use to amplify clear polymorphic bands. To be specific, a total of 327 clear DNA fragments were amplified, including 287 polymorphic bands, accounting for 87.77% of the total number of bands amplified. Based on SCoT analysis, the genetic identity (GI) among 20 strains ranged from 0.187 5 to 0.937 5; to be specific, GI between W2 and W3 and that between W11 and W12 reached the maximum of 0. 9375; GI between W15 and W18 was the minimum of 0.187 5. Based on ISSR analysis, GI among 20 strains ranged from 0. 250 0 to 1.000 0; to be specific, GI between W3, W4 and W9, GI between W15 and W17, and that between W16 and W19 reached the maximum of 1.000; GI between W14 and W18 was the minimum of 0.250 0. Such low genetic identity fully demonstrated great genetic differences among F. velutipes monokaryons. According to results of cluster analysis, at a similarity level of 0.55, 20 F. velutipes monokaryons were significantly divided into three groups using SCoT markers; at a similarity level of 0.66, 20 F. velutipes monokaryons were divided into three groups using ISSR markers. Specifically, W11, W18 and W20 were invariably divided into one group; W15 and W17 were divided into one subgroup. [Conclusion] In this study, two type of markers were used for analysis of genetic diversity among F. velutipes monokaryon strains, which provided scientific and practical basis for screening high-quality monokaryon parents of F. velutipes. [ABSTRACT FROM AUTHOR]

Abstract: Throughout evolution, wood-decaying fungi have adapted to different woody plants, resulting in wide species diversity. Dacrymycetes, which are brown-rot fungi and include host-recurrent species, are useful for studying fungal adaptation to host trees. When estimating the decay abilities of basidiomycetes, the nuclear phases of the mycelium should be considered, since dikaryons are thought to be more efficient wood-decayers than monokaryons; however, the difference in their physiological performances remains largely untested. In this study, we verified the decay capabilities of dikaryotic and monokaryotic mycelia and tested the hypothesis that the host tree-recurrence of wood-decaying fungi results from their resource utilization in each host wood. The mass loss caused by eight dacrymycetous species from wood of four tree species was investigated in pure cultures. The decomposition ability of dikaryons was greater than that of monokaryons in these experiments. Dikaryotization is expected to raise certain physiological parameters, such as the quantity and variety of wood-decomposing enzymes, thus enhancing the decomposition rate of wood decomposers. The high decomposition ability of dikaryons suggests their superiority over monokaryons to survive under natural conditions. All dacrymycetous strains caused high mass loss from Pinus wood, the main host tree of Dacrymycetes. However, most of the individual tested strains did not cause the greatest mass loss from the wood of their original host group. This result suggested that host-recurrence can be partly explained by resource utilization, but it is likely that other micro-organisms and abiotic factors also affect host-recurrence in the field environment. [Copyright &y& Elsevier]

The problems in precise discrimination of monokaryotic isolates of edible fungi hindered the breeders to enhance the improvement cycle of mushroom strains in an effective manner. In current study, 5' end of intergenic spacer 2 (IGS2) region was amplified and used to assist categorizing the selected monokaryotic isolates of Pleurotus pulmonarius into two distinct groups (type A and B). Moreover, the dikaryotic isolates were able to produce double-banded PCR product and the monokaryons create only one unique amplicon. Candidate region approach was used in this study and enabled pedigree history to be recorded, and thus breeders are able to make informative decisions. Hence, this approach promotes time saving and breeding space to be allocated for strain improvement programmes. Meanwhile, this highly variable DNA marker can be used for the confirmation of successfully crossed strains. Eventually, this methodology can assist towards detecting efficient mating partners of P. pulmonarius in any breeding programmes including selective breeding, production of high yield hybrids and studies on structure mating types. [ABSTRACT FROM AUTHOR]

Highlights: [•] We try to develop the new strain with a longer shelf-life on Pleurotus eryngii. [•] The new hybrid strain C5 was developed by mono–mono crossing. [•] In the case of strain C5, the quality of the fruiting bodies did not change and remained normal after a period of 40d at 4°C. [•] C5 is characterized by improved storability after harvesting. [ABSTRACT FROM AUTHOR]

Monokaryotic strains of Helicobasidium mompa were used as vectors of a mycovirus between various H. mompa isolates to examine the transmissibility of one of the mycoviruses, totivirus (HmTV1-17 virus) in the hypovirulent isolate V17 of H. mompa. The isolates that acquired HmTV1-17 virus were also examined for any alteration in the virulence. Twelve dikaryotic isolates of H. mompa, belonging to 11 mycelial compatibility groups (MCGs) and being mycelially incompatible with isolate V17, were used as recipients of HmTV1-17 virus. Two monokaryotic isolates that were mycelially incompatible with isolate V17 and all of the recipients were also used as vectors of HmTV1-17 virus between isolate V17 and the recipients. When isolate V17 and recipients were directly paired on plate media, HmTV1-17 virus was transmitted from isolate V17 into 2 of the 12 recipients (i.e., 2 of the 11 MCGs). Two monokaryotic strains were paired with isolate V17, and the monokaryotic strains that acquired HmTV1- 17 virus were then used as new virus donors. When the monokaryotic strains containing HmTV1-17 virus were paired with the 12 recipients, HmTV1-17 virus was transmitted into 7 of the 12 recipients from the monokaryotic strains (i.e., 7 of 11 MCGs). Based on these results, we concluded that monokaryotic strains could act as vectors to transmit HmTV1-17 virus into H. mompa isolates. When four of the H. mompa isolates that acquired HmTV1-17 virus were used to inoculate apple rootstock Malus prunifolia, the virulence of all of the isolates was attenuated from that of their parental isolates. Moreover, because the DNA fingerprints of the fungal isolates that acquired HmTV1-17 virus were the same as those of their parental isolates, the infection with HmTV1-17 virus is considered the cause of virulence attenuation of H. mompa. [ABSTRACT FROM AUTHOR]

To examine the potential of a method of double-stranded (ds) RNA infection to Helicobasidium mompa, the transmissibility of dsRNA between strains of this fungus was investigated. Strain V70 was used as a dsRNA donor. The dsRNA recipients were six strains that were mycelially incompatible with V70, plus two monokaryotic strains. Random amplified polymorphic DNA analysis suggested that the mycelially incompatible strains were genetically different mutually; however, the analysis also suggested that V70 was genetically homogeneous with the two monokaryotic strains. When V70 was paired with either of the mycelially incompatible strains, the dsRNAs did not transmit to the recipients at all. When V70 was paired with the two monokaryotic strains, the dsRNAs were transmitted to the monokaryotic strains. The two monokaryotic strains, which had acquired dsRNAs from V70 in the previous experiment, were used as new dsRNA donors in a next experiment so that we could investigate dsRNA transmission from these monokaryotic strains to the six strains used in the previous experiment. One of the monokaryotic strains permitted dsRNA transmission to two of the six recipients. We conclude that we can infect genetically different strains of H. mompa with dsRNA using the monokaryotic strains. [ABSTRACT FROM AUTHOR]

Monokaryotic Pycnoporus cinnabarinus strains were obtained from the dikaryotic strain I-938. One of these, designated MK18, consistently produced high laccase activity. In cultures of MK18 and I-938 where ferulic acid was added as laccase inducer, laccase activity was enhanced about 2.5-fold reaching 3400 U/l for the MK18 strain. Laccase was purified to homogeneity and under the selected growth conditions, only one isoform of the enzyme was produced. The N-terminal sequence was similar to the amino terminal sequence of laccase II from Trametes versicolor. The enzyme was stable at 60 ∘C for more than 1 h. [ABSTRACT FROM AUTHOR]