Search Results (47)

Thanks to next-generation sequencing (NGS) technologies, the diversity of fungi can now be investigated through the analysis of their genome sequences. Naviculisporaceae is a family within the Sordariales, whose diversity is not well-known, with only one genome sequence published for this family. Here, we report on the isolation and cultivation of 20 new strains of Naviculisporaceae. Their genome sequences, as well as those of the five commercially available strains, were determined, thus providing complete genome sequences for 25 new Naviculisporaceae strains. Species delimitation was conducted using a combination of (1) ITS + LSU phylogenetic analysis of the new isolates along with other known species of the family, (2) comparisons between DNA barcode sequences of the new strains with those of the known species, and (3) average genome-wide nucleotide identity calculation. We built a phylogenomic tree and studied the organization of the mating-type locus. In vitro fruiting was obtained for 16 strains, enabling the definition of seven new species, namely Pseudorhypophila gallica, Pseudorhypophila guyanensis Rhypophila alpibus, Rhypophila brasiliensis, Rhypophila camarguensis, Rhypophila reunionensis and Rhypophila thailandica, as well as two new combinations, namely Pseudorhypophila latipes and Pseudorhypophila oryzae. Eight strains for which in vitro fruiting was not obtained may belong to additional new species. These results expand the known diversity of the Naviculisporaceae and greatly enlarge the genomic data available for the family. Full article

Stropharia rugosoannulata is a widely cultivated edible fungus with high economic and nutritional value. It is a tetrapolar heterothallic basidiomycete. The development of single nucleotide polymorphism (SNP) markers for mating-type identification holds considerable promise for enhancing breeding efficiency. In our study, one group of test crosses and three-round mating experiments from one parental strain were conducted in order to ascertain the mating type in this species. Segregation distortion in mating types was observed after single-spore isolation, which was deviated from Mendelian inheritance. The monokaryotic strain Q25 was derived from the dikaryotic mycelium S1 of S. rugosoannulata. The genome map of strain Q25 with 48.27 Mb and 14 chromosomes was constructed using genomic, transcriptomic, and high-throughput chromosome conformation capture (Hi-C) sequencing technologies. The locations of mating-type loci were identified using genomic annotation. The mating-type A locus is located in chromosome 1, with the gene sequence of β-fg, HD2, HD1, and MIP. The mating-type B locus is located in chromosome 12. It contains five pheromone receptors and five pheromone precursor genes. Two pairs of highly specific and stable primers were designed based on SNP loci in A and B mating types. A1, A2, B1, and B2 alleles were precisely distinguished with these primers, which were subsequently applied in cultivation experiments. This study lays a foundation for the precise breeding of S. rugosoannulata. Full article

The A mating-type locus in Schizophyllum commune, which encodes homeodomain (HD) transcription factors, is essential for regulating sexual compatibility and development. While the role of the Aα sublocus and its Y-Z HD protein complex is adequality understood, the function of HD proteins at the Aβ sublocus remains unclear. In this study, we analyzed the Aβ sublocus of eight monokaryotic S. commune strains derived from the parental dikaryotic strain 20R-7-Z01 and identified four HD genes, abr, abs, abv, and abq, located at the Aβ sublocus. These genes encode two HD1 proteins (S and Q) and two HD2 proteins (R and V). Protein structure prediction, interaction assays, and in vivo functional analyses revealed that R-S and V-Q interactions independently regulate sexual compatibility and fruiting body development. This research highlights the critical role of the Aβ sublocus in fungal reproduction and provides valuable insights for breeding edible and medicinal S. commune strains. Full article

Cyclocybe chaxingu is an edible wood-decaying fungus widely cultivated in China, valued for its nutritional and economic significance. Despite its importance, molecular and genetic breeding studies on C. chaxingu have been limited by the lack of comprehensive genomic information. In this study, we performed whole-genome sequencing of the type strain JAUCC1847 of C. chaxingu for the first time and conducted extensive genomic and transcriptomic analyses. We assembled a high-quality genome of the C. chaxingu strain C27, with a total length of 50.79 Mb and a GC content of 50.90%. Comparative genomic analysis revealed a close evolutionary relationship with species from the genera Agrocybe and Stropharia, suggesting a recent common ancestor. The high ANI values between C. chaxingu, Agrocybe chaxingu, and Agrocybe cylindracea indicate a close phylogenetic relationship, raising the possibility of synonymy among these strains. Genome annotation identified a rich array of 573 carbohydrate-active enzymes, highlighting the metabolic diversity of C. chaxingu, particularly in lignocellulose degradation. Comprehensive analysis of the A and B mating-type locus in C. chaxingu revealed the distribution and structural characteristics of mating-type genes, providing crucial genetic information for further studies on the reproductive biology of this species. Transcriptomic analysis revealed distinct gene expression patterns in mycelia, stipe, and cap, reflecting their functional specialization. GO and KEGG enrichment analyses demonstrated the stipe’s association with structural integrity and transport, while the cap is linked to metabolic activity, gene regulation, stress responses, and DNA repair. These insights clarify the taxonomic status of C. chaxingu, supporting its recognition within the genus Cyclocybe and providing a valuable resource for future research and breeding programs. Full article

Schizophyllum commune, a Basidiomycota fungus with a tetrapolar mating system, serves as a key model for studying sexual reproduction. In this study, two distinct mating subtypes (I and II) were identified in strain 20R-7-ZF01, isolated from subseafloor sediment, which exhibited eight different mating interaction phenotypes. Intra-subtypes exhibited colony-symmetric tetrapolar interactions (G1), whereas inter-subtype crosses yielded colony-asymmetric phenotypes (G2) and a reduced number of fruiting bodies. Nuclear migration analysis revealed that both subtypes follow the same sexual reproductive process, suggesting functional similarities despite the different reproductive outcomes. Gene silencing of mating-type loci identified the genes bbp2-9 and bbp2-7 within the B locus as key factors in determining mating subtype identity. Additionally, a similar pattern of mating subtype differentiation was observed in five other S. commune strains from both subseafloor and terrestrial environments. These findings highlight the genetic diversity within S. commune, challenge the classical understanding of fungal mating systems, and provide new insights into the genetic evolutionary mechanisms governing fungi with tetrapolar mating systems. Full article

During sexual reproduction, the freshwater ciliate Tetrahymena thermophila sheds membrane-bound vesicles into the extracellular environment (cEMVs: ciliary extracellular micro-vesicles). We provide evidence that 100 nm vesicles shed from the cilia of starved cells promote mating between cells of complementary mating types. A proteomic analysis revealed that these EMVs are decorated with mating-type proteins expressed from the MAT locus, proteins that define a cell’s sex (one of seven). Once the mating junction is established between cells, smaller 60 nm vesicles (junction vesicles) appear within the extracellular gap that separates mating partners. Junction vesicles (jEMVs) may play a role in remodeling the mating junction through which gametic pronuclei are exchanged. Evidence is presented demonstrating that cells must be able to internalize extracellular signals via some form of endocytosis in order to trigger conjugation. Finally, an evolutionarily conserved fusogen (Hap2) implicated in pore formation also appears necessary for jEMV processing. This system offers an excellent opportunity for studies on ectosome shedding, intercellular signaling and shed vesicle uptake by macro-pinocytosis, as they relate to sexual reproduction in the ciliate Tetrahymena thermophila. Full article

Species of the genus Diaporthe have a mating-type system with the two mating types MAT1-1 and MAT1-2, like other ascomycetes. They can either be heterothallic, which means that any isolate only possesses one of the two mating types and needs a mating partner for sexual reproduction, or homothallic, which means that they possess both mating types and are self-fertile. For several Diaporthe species, no sexual reproduction has been observed so far. Using PCR with primers specific to the defining genes MAT1-1-1 and MAT1-2-1, we determined the mating types of 33 isolates of Diaporthe caulivora, D. eres, D. longicolla, and D. novem from central Europe. In addition, we partially sequenced the mating-type genes of 25 isolates. We found that different D. longicolla isolates either possess MAT1-1-1 or MAT1-2-1, making the species heterothallic, which is in contrast to previous studies and the general assumption that D. longicolla only reproduces asexually. D. eres and D. novem were also found to be heterothallic. Using genomic sequence information and re-sequencing of DNA and RNA, we identified the MAT1-1-1 gene in D. caulivora and present here the full sequence of the mating-type locus of this homothallic species. Finally, we used sequence information from MAT1-1-1 and MAT1-2-1, respectively, for improved phylogenetic resolution of our isolates. Full article

Pholiota nameko (T. Ito) S. Ito and S. Imai is an emerging wild mushroom species belonging to the genus Pholiota. Its unique brown–yellow appearance and significant biological activity have garnered increasing attention in recent years. However, there is a relative lack of research on the biological characteristics and genetics of P. nameko, which greatly limits the potential for an in-depth exploration of this mushroom in the research fields of molecular breeding and evolutionary biology. This study aimed to address that gap by employing Illumina and Nanopore sequencing technologies to perform whole-genome sequencing, de novo assembly, and annotation analysis of the P. nameko ZZ1 strain. Utilizing bioinformatics methods, we conducted a comprehensive analysis of the genomic characteristics of this strain and successfully identified candidate genes associated with its mating type, carbohydrate-active enzymes, virulence factors, pan-genome, and drug resistance functions. The genome of P. nameko ZZ1 is 24.58 Mb in size and comprises 33 contigs, with a contig N50 of 2.11 Mb. A hylogenetic analysis further elucidated the genetic relationship between P. nameko and other Pholiota, revealing a high degree of collinearity between P. nameko and ZZ1. In our enzyme analysis, we identified 246 enzymes in the ZZ1 genome, including 68 key carbohydrate-active enzymes (CAZymes), and predicted the presence of 11 laccases, highlighting the strain’s strong potential for cellulose degradation. We conducted a pan-genomic analysis of five closely related strains of Pholiota, yielding extensive genomic information. Among these, there were 2608 core genes, accounting for 21.35% of the total genes, and 135 dispensable genes, highlighting significant genetic diversity among Pholiota and further confirming the value of pan-genomic analysis in uncovering species diversity. Notably, while we successfully identified the A-mating-type locus, composed of the homeodomain protein genes HD1 and HD2 in ZZ1, we were unable to obtain the B-mating-type locus due to technical limitations, preventing us from acquiring the pheromone receptor of the B-mating-type. We plan to supplement these data in future studies and explore the potential impact of the B-mating-type locus on the current findings. In summary, the genome data of ZZ1 presented in this study are not only valuable resources for understanding the genetic basis of this species, but also serve as a crucial foundation for subsequent genome-assisted breeding, research into cultivation technology, and the exploration of its nutritional and potential medicinal value. Full article

The methylotrophic yeast Komagataella kurtzmanii belongs to the group of homothallic fungi that are able to spontaneously change their mating type by inversion of chromosomal DNA in the MAT locus region. As a result, natural and genetically engineered cultures of these yeasts typically contain a mixture of sexually dimorphic cells that are prone to self-diploidisation and spore formation accompanied by genetic rearrangements. These characteristics pose a significant challenge to the development of genetically stable producers for industrial use. In the present study, we constructed heterothallic strains of K. kurtzmanii, ensuring a constant mating type by unifying the genetic sequences in the active and silent MAT loci. To obtain such strains, we performed site-directed inactivation of one of the two yeast MAT loci, replacing its sequence with a selective HIS4 gene surrounded by I-SceI meganuclease recognition sites. We then used transient expression of the SCE1 gene, encoding a recombinant I-SceI meganuclease, to induce site-specific cleavage of HIS4, followed by damage repair by homologous recombination in mutant cells. As a result, heterothallic strains designated ‘Y-727-2(alpha)’ and ‘Y-727-9(a)’, which correspond to the α and a mating type, respectively, were obtained. The strains demonstrated a loss of the ability to self-diploidize. The results of PCR and whole genome analysis confirmed the identity of the contents of the MAT loci. Analysis of the genomes of the final strains, however, revealed a fusion of chromosome 3 and chromosome 4 in strain Y-727-2(alpha)-1. This finding was subsequently confirmed by pulsed-field gel electrophoresis of yeast chromosomes. However, the ability of the Y-727-2(alpha)-derived producers to efficiently secrete recombinant β-galactosidase was unaffected by this genomic rearrangement. Full article

Population genetics describes evolutionary processes, focusing on the variation within and between species and the forces shaping this diversity. Evolution reflects information accumulated in genomes, enhancing organisms’ adaptation to their environment. In this paper, I propose a model that begins with the distribution of mating based on mutual fitness and progresses to viable adult genotype distribution. At each stage, the changes result in different measures of information. The evolutionary dynamics at each stage of the model correspond to certain aspects of interest, such as the type of mating, the distribution of genotypes in regard to mating, and the distribution of genotypes and haplotypes in the next generation. Changes to these distributions are caused by variations in fitness and result in Jeffrey’s divergence values other than zero. As an example, a model of hybrid sterility is developed of a biallelic locus, comparing the information indices associated with each stage of the evolutionary process. In conclusion, the informational perspective seems to facilitate the connection between cause and effect and allows the development of statistical tests to perform hypothesis testing against zero-information null models (random mating, no selection, etc.). The informational perspective could contribute to clarify, deepen, and expand the mathematical foundations of evolutionary theory. Full article

Frogeye leaf spot on soybeans is traditionally considered as a southern disease in the United States but its impact in North Central USA has been rising in recent years. In this study, we investigated the population structure and mating type distribution in the C. sojina population from Indiana, USA. Based on 27 single nucleotide polymorphism markers, 49 multi-locus genotypes (MLGs) were identified in 234 isolates collected from 29 counties in Indiana in 2020. Bayesian analysis grouped the 49 MLGs into three clusters. This grouping was supported by principal coordinate analysis and, in large part, by the unweighted pair group method with arithmetic mean and minimal spanning tree. Only one mating-type idiomorph was found in each isolate and in each MLG. The MAT1-1 idiomorph was found in 22 MLGs and the MAT1-2 idiomorph was found in 27 MLGs. Based on clone-corrected data, the distribution of mating-type idiomorphs did not deviate significantly from 1:1 ratio in Indiana as a whole and in 22 out of 24 counties where two or more MLGs were found. Thirty MLGs contained QoI-resistant isolates and 22 MLGs contained QoI-sensitive isolates, with three MLGs containing both types of isolates. MLG1, the most common MLG with 90 isolates, contained mostly QoI-resistant isolates. Interestingly, MLG1 was also the dominant genotype in the Tennessee population collected in 2015, suggesting that MLG1 has been a dominant genotype in a wider region for many years. Based on the standard index of association ($\overline{r}$_d), the Indiana population as a whole was in significant linkage disequilibrium. However, in five out of 16 counties where three or more MLGs were found, the null hypothesis of linkage equilibrium was not rejected. Tests of linkage disequilibrium between locus pairs showed that 33.3% of locus pairs on the same contigs were in significant disequilibrium and 17.7% of locus pairs on different contigs were in significant disequilibrium. The possibility of a cryptic sexual stage was discussed. Full article

Sexual reproduction in ascomycetes is controlled by the mating-type (MAT) locus. (Pseudo)homothallic reproduction has been hypothesized on the basis of genetic data from Hirsutella sinensis (Genotype #1 of Ophiocordyceps sinensis). However, the differential occurrence and differential transcription of mating-type genes in the MAT1-1 and MAT1-2 idiomorphs were found in the genome and transcriptome assemblies of H. sinensis, and the introns of the MAT1-2-1 transcript were alternatively spliced with an unspliced intron I that contains stop codons. These findings reveal that O. sinensis reproduction is controlled at the genetic, transcriptional, and coupled transcriptional-translational levels. This study revealed that mutant mating proteins could potentially have various secondary structures. Differential occurrence and transcription of the a-/α-pheromone receptor genes were also found in H. sinensis. The data were inconsistent with self-fertilization under (pseudo)homothallism but suggest the self-sterility of H. sinensis and the requirement of mating partners to achieve O. sinensis sexual outcrossing under heterothallism or hybridization. Although consistent occurrence and transcription of the mating-type genes of both the MAT1-1 and MAT1-2 idiomorphs have been reported in natural and cultivated Cordyceps sinensis insect-fungi complexes, the mutant MAT1-1-1 and α-pheromone receptor transcripts in natural C. sinensis result in N-terminal or middle-truncated proteins with significantly altered overall hydrophobicity and secondary structures of the proteins, suggesting heterogeneous fungal source(s) of the proteins and hybridization reproduction because of the co-occurrence of multiple genomically independent genotypes of O. sinensis and >90 fungal species in natural C. sinensis. Full article

Thielaviopsis paradoxa sensu lato is a soilborne fungal pathogen that causes Thielaviopsis trunk rot and heart rot in palms. The loss of structural integrity resulting from trunk rot can cause the palm trunk to collapse suddenly and poses a serious threat to life and property. Even though rudimentary knowledge about the Thielaviopsis infection process in palms is available, nothing is known about the T. paradoxa species complex in the US. The aim of this study was to characterize T. paradoxa s. lat. isolates collected from diseased palms grown in Florida. Multi-locus phylogeny using three genes, ITS, β-tubulin, and tef1-α, revealed that the isolates separate into two distinct clades with high bootstrap support. The majority of the isolates clustered with the species T. ethacetica, while two isolates formed a separate clade, distinct from T. musarum, and might represent an undescribed Thielaviopsis species. One representative isolate from each clade, when grown on three distinct media and at four different temperatures, showed differences in gross colony morphology, as well as growth rates. The T. ethacetica isolate TP5448 and the Thielaviopsis sp. isolate PLM300 grew better at opposite ends of the temperature spectrum tested in this study, i.e., 35 °C and 10 °C, respectively. In pathogenicity assays on whole plants, the T. ethacetica isolate proved to be more aggressive than Thielaviopsis sp. isolate PLM300, as it produced larger lesions when inoculated on wounded leaflets. An unequal distribution was observed for the mating-type locus of T. ethacetica, as 12 isolates carried the MAT1-1-1 allele, while the status for four isolates remained undefined. Variation in mycelial growth in response to different fungicides was also observed between the two clades. These results demonstrate the existence of two Thielaviopsis clades that can infect palms in Florida and underscore the need for targeted sampling to help uncover the diversity of Thielaviopsis species across palm-growing regions in the US. Full article

The aspergilli comprise a diverse group of filamentous fungi spanning over 200 million years of evolution. In this work, we report a clarification of the phylogenetic relationship between A. carbonarius and A. tubingensis via the screening of ITS-5.8RDNA, (niiA-niaD), ß-tubulin, and eEF-1 genes. The phylogenetic analysis of aspergilli ITS-5.8rDNA sequences divided A. carbonarius and A. tubingensis into two coherent clusters and showed a close intergeneric relationship, which is in keeping with the existing morphological and taxonomic classification. Herein, A. carbonarius exhibits a complete similarity (100%) for the three target genes: intergenic region of (niiA-niaD), ß-tubulin, and eEF-1. The tree resulting from a bootstrap analysis indicates branch points when the significance is 98% minimum for each gene (ß-tubulin and eEF-1). The phylogenetic analysis of the aspergilli genome structure provided a quantitative evaluation of the forces driving long-term eukaryotic genome evolution. It also led to an experimentally validated model of mating-type locus evolution, suggesting the potential for sexual reproduction in A. carbonarius and A. tubingensis. This is the first work describing the evolutionary relationship between both species. Nevertheless, this discovery might be viewed as typical during the process of new taxonomic evolution. Full article

Grifola frondosa is a valuable edible fungus with high nutritional and medicinal values. The mating systems of fungi not only offer practical strategies for breeding, but also have far-reaching effects on genetic variability. Grifola frondosa has been considered as a sexual species with a tetrapolar mating system based on little experimental data. In the present study, one group of test crosses and six groups of three-round mating experiments from two parental strains were conducted to determine the mating system in G. frondosa. A chi-squared test of the results of the test-cross mating experiments indicated that they satisfied Mendelian segregation, while a series of three-round mating experiments showed that Mendelian segregation was not satisfied, implying a segregation distortion phenomenon in G. frondosa. A genomic map of the G. frondosa strain, y59, grown from an LMCZ basidiospore, with 40.54 Mb and 12 chromosomes, was generated using genome, transcriptome and Hi-C sequencing technology. Based on the genomic annotation of G. frondosa, the mating-type loci A and B were located on chromosomes 1 and 11, respectively. The mating-type locus A coded for the β-fg protein, HD1, HD2 and MIP, in that order. The mating-type locus B consisted of six pheromone receptors (PRs) and five pheromone precursors (PPs) in a crossed order. Moreover, both HD and PR loci may have only one sublocus that determines the mating type in G. frondosa. The nonsynonymous SNP and indel mutations between the A₁B₁ and A₂B₂ mating-type strains and the reference genome of y59 only occurred on genes HD2 and PR1/2, preliminarily confirming that the mating type of the y59 strain was A₁B₂ and not A₁B₁. Based on the genetic evidence and the more reliable molecular evidence, the results reveal that the mating system of G. frondosa is tetrapolar. This study has important implications for the genetics and hybrid breeding of G. frondosa. Full article