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1
Kües, Ursula, and Lorna A. Casselton. "Fungal mating type genes — regulators of sexual development." Mycological Research 96, no. 12 (December 1992): 993–1006. http://dx.doi.org/10.1016/s0953-7562(09)80107-x.
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Raudaskoski, Marjatta, and Erika Kothe. "Basidiomycete Mating Type Genes and Pheromone Signaling." Eukaryotic Cell 9, no. 6 (February 26, 2010): 847–59. http://dx.doi.org/10.1128/ec.00319-09.
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ABSTRACT The genome sequences of the basidiomycete Agaricomycetes species Coprinopsis cinerea, Laccaria bicolor, Schizophyllum commune, Phanerochaete chrysosporium, and Postia placenta, as well as of Cryptococcus neoformans and Ustilago maydis, are now publicly available. Out of these fungi, C. cinerea, S. commune, and U. maydis, together with the budding yeast Saccharomyces cerevisiae, have been investigated for years genetically and molecularly for signaling in sexual reproduction. The comparison of the structure and organization of mating type genes in fungal genomes reveals an amazing conservation of genes regulating the sexual reproduction throughout the fungal kingdom. In agaricomycetes, two mating type loci, A, coding for homeodomain type transcription factors, and B, encoding a pheromone/receptor system, regulate the four typical mating interactions of tetrapolar species. Evidence for both A and B mating type genes can also be identified in basidiomycetes with bipolar systems, where only two mating interactions are seen. In some of these fungi, the B locus has lost its self/nonself discrimination ability and thus its specificity while retaining the other regulatory functions in development. In silico analyses now also permit the identification of putative components of the pheromone-dependent signaling pathways. Induction of these signaling cascades leads to development of dikaryotic mycelia, fruiting body formation, and meiotic spore production. In pheromone-dependent signaling, the role of heterotrimeric G proteins, components of a mitogen-activated protein kinase (MAPK) cascade, and cyclic AMP-dependent pathways can now be defined. Additionally, the pheromone-dependent signaling through monomeric, small GTPases potentially involved in creating the polarized cytoskeleton for reciprocal nuclear exchange and migration during mating is predicted.
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Zhang, Lei, Rudeina A. Baasiri, and Neal K. Van Alfen. "Viral Repression of Fungal Pheromone Precursor Gene Expression." Molecular and Cellular Biology 18, no. 2 (February 1, 1998): 953–59. http://dx.doi.org/10.1128/mcb.18.2.953.
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ABSTRACT Biological control of chestnut blight caused by the filamentous ascomycete Cryphonectria parasitica can be achieved with a virus that infects this fungus. This hypovirus causes a perturbation of fungal development that results in low virulence (hypovirulence), poor asexual sporulation, and female infertility without affecting fungal growth in culture. At the molecular level, the virus is known to affect the transcription of a number of fungal genes. Two of these genes,Vir1 and Vir2, produce abundant transcripts in noninfected strains of the fungus, but the transcripts are not detectable in virus-infected strains. We report here that these two genes encode the pheromone precursors of the Mat-2 mating type of the fungus; consequently, these genes have been renamedMf2/1 and Mf2/2. To determine if the virus affects the mating systems of both mating types of this fungus, the pheromone precursor gene, Mf1/1, of a Mat-1strain was cloned and likewise was found to be repressed in virus-infected strains. The suppression of transcription of the pheromone precursor genes of this fungus could be the cause of the mating defect of infected strains of the fungus. Although published reports suggest that a Gαi subunit may be involved in this regulation, our results do not support this hypothesis. The prepropheromone encoded by Mf1/1 is structurally similar to that of the prepro-p-factor of Schizosaccharomyces pombe. This is the first description of the complete set of pheromone precursor genes encoded by a filamentous ascomycete.
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Wang, Ping, Connie B. Nichols, Klaus B. Lengeler, Maria E. Cardenas, Gary M. Cox, John R. Perfect, and Joseph Heitman. "Mating-Type-Specific and Nonspecific PAK Kinases Play Shared and Divergent Roles in Cryptococcus neoformans." Eukaryotic Cell 1, no. 2 (April 2002): 257–72. http://dx.doi.org/10.1128/ec.1.2.257-272.2002.
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ABSTRACT Cryptococcus neoformans is an opportunistic fungal pathogen with a defined sexual cycle involving fusion of haploid MATα and MATa cells. Virulence has been linked to the mating type, and MATα cells are more virulent than congenic MATa cells. To study the link between the mating type and virulence, we functionally analyzed three genes encoding homologs of the p21-activated protein kinase family: STE20α, STE20a, and PAK1. In contrast to the STE20 genes that were previously shown to be in the mating-type locus, the PAK1 gene is unlinked to the mating type. The STE20α, STE20a, and PAK1 genes were disrupted in serotype A and D strains of C. neoformans, revealing central but distinct roles in mating, differentiation, cytokinesis, and virulence. ste20α pak1 and ste20a pak1 double mutants were synthetically lethal, indicating that these related kinases share an essential function. In summary, our studies identify an association between the STE20α gene, the MATα locus, and virulence in a serotype A clinical isolate and provide evidence that PAK kinases function in a MAP kinase signaling cascade controlling the mating, differentiation, and virulence of this fungal pathogen.
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Lengeler, Klaus B., Deborah S. Fox, James A. Fraser, Andria Allen, Keri Forrester, Fred S. Dietrich, and Joseph Heitman. "Mating-Type Locus of Cryptococcus neoformans: a Step in the Evolution of Sex Chromosomes." Eukaryotic Cell 1, no. 5 (October 2002): 704–18. http://dx.doi.org/10.1128/ec.1.5.704-718.2002.
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ABSTRACT The sexual development and virulence of the fungal pathogen Cryptococcus neoformans is controlled by a bipolar mating system determined by a single locus that exists in two alleles, α and a. The α and a mating-type alleles from two divergent varieties were cloned and sequenced. The C. neoformans mating-type locus is unique, spans >100 kb, and contains more than 20 genes. MAT-encoded products include homologs of regulators of sexual development in other fungi, pheromone and pheromone receptors, divergent components of a MAP kinase cascade, and other proteins with no obvious function in mating. The α and a alleles of the mating-type locus have extensively rearranged during evolution and strain divergence but are stable during genetic crosses and in the population. The C. neoformans mating-type locus is strikingly different from the other known fungal mating-type loci, sharing features with the self-incompatibility systems and sex chromosomes of algae, plants, and animals. Our study establishes a new paradigm for mating-type loci in fungi with implications for the evolution of cell identity and self/nonself recognition.
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Samils, Nicklas, Anastasia Gioti, Magnus Karlsson, Yu Sun, Takao Kasuga, Eric Bastiaans, Zheng Wang, Ning Li, Jeffrey P. Townsend, and Hanna Johannesson. "Sex-linked transcriptional divergence in the hermaphrodite fungus Neurospora tetrasperma." Proceedings of the Royal Society B: Biological Sciences 280, no. 1764 (August 7, 2013): 20130862. http://dx.doi.org/10.1098/rspb.2013.0862.
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In the filamentous ascomycete Neurospora tetrasperma , a large (approx. 7 Mbp) region of suppressed recombination surrounds the mating-type ( mat ) locus. While the remainder of the genome is largely homoallelic, this region of recombinational suppression, extending over 1500 genes, is associated with sequence divergence. Here, we used microarrays to examine how the molecular phenotype of gene expression level is linked to this divergent region, and thus to the mating type. Culturing N. tetrasperma on agar media that induce sexual/female or vegetative/male tissue, we found 196 genes significantly differentially expressed between mat A and mat a mating types. Our data show that the genes exhibiting mat -linked expression are enriched in the region genetically linked to mating type, and sequence and expression divergence are positively correlated. Our results indicate that the phenotype of mat A strains is optimized for traits promoting sexual/female development and the phenotype of mat a strains for vegetative/male development. This discovery of differentially expressed genes associated with mating type provides a link between genotypic and phenotypic divergence in this taxon and illustrates a fungal analogue to sexual dimorphism found among animals and plants.
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Ma, Wen-Juan, Fantin Carpentier, Tatiana Giraud, and Michael E. Hood. "Differential Gene Expression between Fungal Mating Types Is Associated with Sequence Degeneration." Genome Biology and Evolution 12, no. 4 (February 14, 2020): 243–58. http://dx.doi.org/10.1093/gbe/evaa028.
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Abstract Degenerative mutations in non-recombining regions, such as in sex chromosomes, may lead to differential expression between alleles if mutations occur stochastically in one or the other allele. Reduced allelic expression due to degeneration has indeed been suggested to occur in various sex-chromosome systems. However, whether an association occurs between specific signatures of degeneration and differential expression between alleles has not been extensively tested, and sexual antagonism can also cause differential expression on sex chromosomes. The anther-smut fungus Microbotryum lychnidis-dioicae is ideal for testing associations between specific degenerative signatures and differential expression because 1) there are multiple evolutionary strata on the mating-type chromosomes, reflecting successive recombination suppression linked to mating-type loci; 2) separate haploid cultures of opposite mating types help identify differential expression between alleles; and 3) there is no sexual antagonism as a confounding factor accounting for differential expression. We found that differentially expressed genes were enriched in the four oldest evolutionary strata compared with other genomic compartments, and that, within compartments, several signatures of sequence degeneration were greater for differentially expressed than non-differentially expressed genes. Two particular degenerative signatures were significantly associated with lower expression levels within differentially expressed allele pairs: upstream insertion of transposable elements and mutations truncating the protein length. Other degenerative mutations associated with differential expression included nonsynonymous substitutions and altered intron or GC content. The association between differential expression and allele degeneration is relevant for a broad range of taxa where mating compatibility or sex is determined by genes located in large regions where recombination is suppressed.
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Robertson, C. Ian, Kirk A. Bartholomew, Charles P. Novotny, and Robert C. Ullrich. "Deletion of the Schizophyllum commune Aα Locus: The Roles of Aα Y and Z Mating-Type Genes." Genetics 144, no. 4 (December 1, 1996): 1437–44. http://dx.doi.org/10.1093/genetics/144.4.1437.
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The Aα locus is one of four master regulatory loci that determine mating type and regulate sexual development in Schizophyllum commune. We have made a plasmid containing a URA1 gene disruption of the Aα Y1 gene. Y1 is the sole Aα gene in Aα1 strains. We used the plasmid construction to produce an Aα null (i.e., AαΔ) strain by replacing the genomic Y1 gene with URA1 in an Aα1 strain. To characterize the role of the Aα genes in the regulation of sexual development, we transformed various Aα Y and Z alleles into AαΔ strains and examined the acquired mating types and mating abilities of the transformants. These experiments demonstrate that the Aα Y gene is not essential for fungal viability and growth, that a solitary Z Aα mating-type gene does not itself activate development, that Aβ proteins are sufficient to activate the A developmental pathway in the absence of Aα proteins and confirm that Y and Z genes are the sole determinants of Aα mating type. The data from these experiments support and refine our model of the regulation of A-pathway events by Y and Z proteins.
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Li, Wenjun, Thomas D. Sullivan, Eric Walton, Anna Floyd Averette, Sharadha Sakthikumar, Christina A. Cuomo, Bruce S. Klein, and Joseph Heitman. "Identification of the Mating-Type (MAT) Locus That Controls Sexual Reproduction of Blastomyces dermatitidis." Eukaryotic Cell 12, no. 1 (November 9, 2012): 109–17. http://dx.doi.org/10.1128/ec.00249-12.
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ABSTRACTBlastomyces dermatitidisis a dimorphic fungal pathogen that primarily causes blastomycosis in the midwestern and northern United States and Canada. While the genes controlling sexual development have been known for a long time, the genes controlling sexual reproduction ofB. dermatitidis(teleomorph,Ajellomyces dermatitidis) are unknown. We identified the mating-type (MAT) locus in theB. dermatitidisgenome by comparative genomic approaches. TheB. dermatitidis MATlocus resembles those of other dimorphic fungi, containing either an alpha-box (MAT1-1) or an HMG domain (MAT1-2) gene linked to theAPN2,SLA2, andCOX13genes. However, in some strains ofB. dermatitidis, theMATlocus harbors transposable elements (TEs) that make it unusually large compared to theMATlocus of other dimorphic fungi. Based on theMATlocus sequences ofB. dermatitidis, we designed specific primers for PCR determination of the mating type. TwoB. dermatitidisisolates of opposite mating types were cocultured on mating medium. Immature sexual structures were observed starting at 3 weeks of coculture, with coiled-hyphae-containing cleistothecia developing over the next 3 to 6 weeks. Genetic recombination was detected in potential progeny by mating-type determination, PCR-restriction fragment length polymorphism (PCR-RFLP), and random amplification of polymorphic DNA (RAPD) analyses, suggesting that a meiotic sexual cycle might have been completed. The F1 progeny were sexually fertile when tested with strains of the opposite mating type. Our studies provide a model for the evolution of theMATlocus in the dimorphic and closely related fungi and open the door to classic genetic analysis and studies on the possible roles of mating and mating type in infection and virulence.
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Arzanlou, Mahdi, Pedro W. Crous, and Lute-Harm Zwiers. "Evolutionary Dynamics of Mating-Type Loci of Mycosphaerella spp. Occurring on Banana." Eukaryotic Cell 9, no. 1 (November 13, 2009): 164–72. http://dx.doi.org/10.1128/ec.00194-09.
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ABSTRACT The devastating Sigatoka disease complex of banana is primarily caused by three closely related heterothallic fungi belonging to the genus Mycosphaerella: M. fijiensis, M. musicola, and M. eumusae. Previous phylogenetic work showing common ancestry led us to analyze the mating-type loci of these Mycosphaerella species occurring on banana. We reasoned that this might provide better insight into the evolutionary history of these species. PCR and chromosome-walking approaches were used to clone the mating-type loci of M. musicola and M. eumusae. Sequences were compared to the published mating-type loci of M. fijiensis and other Mycosphaerella spp., and a novel organization of the MAT loci was found. The mating-type loci of the examined Mycosphaerella species are expanded, containing two additional Mycosphaerella-specific genes in a unique genomic organization. The proteins encoded by these novel genes show a higher interspecies than intraspecies homology. Moreover, M. fijiensis, M. musicola, and M. eumusae contain two additional mating-type-like loci, containing parts of both MAT 1-1-1 and MAT 1-2-1. The data indicate that M. fijiensis, M. musicola, and M. eumusae share an ancestor in which a fusion event occurred between MAT 1-1-1 and MAT 1-2-1 sequences and in which additional genes became incorporated into the idiomorph. The new genes incorporated have since then evolved independently in the MAT1-1 and MAT1-2 loci. Thus, these data are an example of the evolutionary dynamics of fungal MAT loci in general and show the great flexibility of the MAT loci of Mycosphaerella species in particular.
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Lee, Jungkwan, Theresa Lee, Yin-Won Lee, Sung-Hwan Yun, and B. Gillian Turgeon. "Shifting fungal reproductive mode by manipulation of mating type genes: obligatory heterothallism of Gibberella zeae." Molecular Microbiology 50, no. 1 (August 22, 2003): 145–52. http://dx.doi.org/10.1046/j.1365-2958.2003.03694.x.
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Li, Wenjun, Banu Metin, Theodore C. White, and Joseph Heitman. "Organization and Evolutionary Trajectory of the Mating Type (MAT) Locus in Dermatophyte and Dimorphic Fungal Pathogens." Eukaryotic Cell 9, no. 1 (October 30, 2009): 46–58. http://dx.doi.org/10.1128/ec.00259-09.
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ABSTRACT Sexual reproduction in fungi is governed by a specialized genomic region, the mating type (MAT) locus, whose gene identity, organization, and complexity are diverse. We identified the MAT locus of five dermatophyte fungal pathogens (Microsporum gypseum, Microsporum canis, Trichophyton equinum, Trichophyton rubrum, and Trichophyton tonsurans) and a dimorphic fungus, Paracoccidioides brasiliensis, and performed phylogenetic analyses. The identified MAT locus idiomorphs of M. gypseum control cell type identity in mating assays, and recombinant progeny were produced. Virulence tests in Galleria mellonella larvae suggest the two mating types of M. gypseum may have equivalent virulence. Synteny analysis revealed common features of the MAT locus shared among these five dermatophytes: namely, a small size (∼3 kb) and a novel gene arrangement. The SLA2, COX13, and APN2 genes, which flank the MAT locus in other Ascomycota are instead linked on one side of the dermatophyte MAT locus. In addition, the transcriptional orientations of the APN2 and COX13 genes are reversed compared to the dimorphic fungi Histoplasma capsulatum, Coccidioides immitis, and Coccidioides posadasii. A putative transposable element, pogo, was found to have inserted in the MAT1-2 idiomorph of one P. brasiliensis strain but not others. In conclusion, the evolution of the MAT locus of the dermatophytes and dimorphic fungi from the last common ancestor has been punctuated by both gene acquisition and expansion, and asymmetric gene loss. These studies further support a foundation to develop molecular and genetic tools for dermatophyte and dimorphic human fungal pathogens.
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Butler, Geraldine. "Fungal Sex and Pathogenesis." Clinical Microbiology Reviews 23, no. 1 (January 2010): 140–59. http://dx.doi.org/10.1128/cmr.00053-09.
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SUMMARYHuman fungal pathogens are associated with diseases ranging from dandruff and skin colonization to invasive bloodstream infections. The major human pathogens belong to theCandida,Aspergillus, andCryptococcusclades, and infections have high and increasing morbidity and mortality. Many human fungal pathogens were originally assumed to be asexual. However, recent advances in genome sequencing, which revealed that many species have retained the genes required for the sexual machinery, have dramatically influenced our understanding of the biology of these organisms. Predictions of a rare or cryptic sexual cycle have been supported experimentally for some species. Here, I examine the evidence that human pathogens reproduce sexually. The evolution of the mating-type locus in ascomycetes (includingCandidaandAspergillusspecies) and basidiomycetes (MalasseziaandCryptococcus) is discussed. I provide an overview of how sex is suppressed in different species and discuss the potential associations with pathogenesis.
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Rau, Domenico, Frank J. Maier, Roberto Papa, Anthony H. D. Brown, Virgilio Balmas, Eva Saba, Wilhelm Schaefer, and Giovanna Attene. "Isolation and characterization of the mating-type locus of the barley pathogen Pyrenophora teres and frequencies of mating-type idiomorphs within and among fungal populations collected from barley landraces." Genome 48, no. 5 (October 1, 2005): 855–69. http://dx.doi.org/10.1139/g05-046.
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Pyrenophora teres f. sp. teres mating-type genes (MAT-1: 1190 bp; MAT-2: 1055 bp) have been identified. Their predicted proteins, measuring 379 and 333 amino acids, respectively, are similar to those of other Pleosporales, such as Pleospora sp., Cochliobolus sp., Alternaria alternata, Leptosphaeria maculans, and Phaeosphaeria nodorum. The structure of the MAT locus is discussed in comparison with those of other fungi. A mating-type PCR assay has also been developed; with this assay we have analyzed 150 isolates that were collected from 6 Sardinian barley landrace populations. Of these, 68 were P. teres f. sp. teres (net form; NF) and 82 were P. teres f. sp. maculata (spot form; SF). Within each mating type, the NF and SF amplification products were of the same length and were highly similar in sequence. The 2 mating types were present in both the NF and the SF populations at the field level, indicating that they have all maintained the potential for sexual reproduction. Despite the 2 forms being sympatric in 5 fields, no intermediate isolates were detected with amplified fragment length polymorphism (AFLP) analysis. These results suggest that the 2 forms are genetically isolated under the field conditions. In all of the samples of P. teres, the ratio of the 2 mating types was consistently in accord with the 1:1 null hypothesis. This ratio is expected when segregation distortion and clonal selection among mating types are absent or asexual reproduction is rare. Overall, sexual reproduction appears to be the major process that equalizes the frequencies of the 2 mating types within populations.Key words: Pyrenophora teres, mating-types, AFLPs, sexual reproduction, selection, barley.
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Große, Verena, and Sven Krappmann. "The Asexual Pathogen Aspergillus fumigatus Expresses Functional Determinants of Aspergillus nidulans Sexual Development." Eukaryotic Cell 7, no. 10 (August 29, 2008): 1724–32. http://dx.doi.org/10.1128/ec.00157-08.
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ABSTRACT The major fungal pathogen of humans, Aspergillus fumigatus, lacks a defined sexual cycle, although the presence of genes encoding putative mating type idiomorphs and regulators of Aspergillus sexual development heightens the potential for cryptic sexuality in this deuteromycete. To test the functionality of these genetic determinants, we transferred the alpha box-encoding mat1-1 idiomorph from an A. fumigatus isolate to the homothallic fertile species Aspergillus nidulans. Abundant formation of fruiting bodies (cleistothecia) containing viable ascospores establishes functionality of this mating type gene product in the transgenic strain. Using a similar approach, we also established that the conserved transcriptional regulator from A. fumigatus, the nsdD gene product, can act as a functional, positively acting factor for A. nidulans cleistothecium development; moreover, high-level expression of NsdD in the endogenous host A. fumigatus profoundly alters hyphal development by triggering the formation of coiled hyphae. Our findings demonstrate that the presumably asexual pathogen A. fumigatus encodes functional regulators of mating and sexual development, thereby potentiating the case for cryptic sexuality in this fungal pathogen.
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Bennett, Richard J., M. Andrew Uhl, Mathew G. Miller, and Alexander D. Johnson. "Identification and Characterization of a Candida albicans Mating Pheromone." Molecular and Cellular Biology 23, no. 22 (November 15, 2003): 8189–201. http://dx.doi.org/10.1128/mcb.23.22.8189-8201.2003.
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ABSTRACT Candida albicans, the most prevalent fungal pathogen of humans, has recently been shown to undergo mating. Here we describe a mating pheromone produced by C. albicans α cells and show that the gene which encodes it (MFα) is required for α cells, but not a cells, to mate. We also identify the receptor for this mating pheromone as the product of the STE2 gene and show that this gene is required for the mating of a cells, but not α cells. Cells of the a mating type respond to the α mating pheromone by producing long polarized projections, similar to those observed in bona fide mating mixtures of C. albicans a and α cells. During this process, transcription of approximately 62 genes is induced. Although some of these genes correspond to those induced in Saccharomyces cerevisiae by S. cerevisiae α-factor, most are specific to the C. albicans pheromone response. The most surprising class encode cell surface and secreted proteins previously implicated in virulence of C. albicans in a mouse model of disseminated candidiasis. This observation suggests that aspects of cell-cell communication in mating may have been evolutionarily adopted for host-pathogen interactions in C. albicans.
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Fraser, James A., Jason E. Stajich, Eric J. Tarcha, Garry T. Cole, Diane O. Inglis, Anita Sil, and Joseph Heitman. "Evolution of the Mating Type Locus: Insights Gained from the Dimorphic Primary Fungal Pathogens Histoplasma capsulatum, Coccidioides immitis, and Coccidioides posadasii." Eukaryotic Cell 6, no. 4 (March 2, 2007): 622–29. http://dx.doi.org/10.1128/ec.00018-07.
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ABSTRACT Sexual reproduction of fungi is governed by the mating type (MAT) locus, a specialized region of the genome encoding key transcriptional regulators that direct regulatory networks to specify cell identity and fate. Knowledge of MAT locus structure and evolution has been considerably advanced in recent years as a result of genomic analyses that enable the definition of MAT locus sequences in many species as well as provide an understanding of the evolutionary plasticity of this unique region of the genome. Here, we extend this analysis to define the mating type locus of three dimorphic primary human fungal pathogens, Histoplasma capsulatum, Coccidioides immitis, and Coccidioides posadasii, using genomic analysis, direct sequencing, and bioinformatics. These studies provide evidence that all three species possess heterothallic bipolar mating type systems, with isolates encoding either a high-mobility-group (HMG) domain or an α-box transcriptional regulator. These genes are intact in all loci examined and have not been subject to loss or decay, providing evidence that the loss of fertility upon passage in H. capsulatum is not attributable to mutations at the MAT locus. These findings also suggest that an extant sexual cycle remains to be defined in both Coccidioides species, in accord with population genetic evidence. Based on these MAT sequences, a facile PCR test was developed that allows the mating type to be rapidly ascertained. Finally, these studies highlight the evolutionary forces shaping the MAT locus, revealing examples in which flanking genes have been inverted or subsumed and incorporated into an expanding MAT locus, allowing us to propose an expanded model for the evolution of the MAT locus in the phylum Ascomycota.
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Coelho, Marco A., André Rosa, Nádia Rodrigues, Álvaro Fonseca, and Paula Gonçalves. "Identification of Mating Type Genes in the Bipolar Basidiomycetous Yeast Rhodosporidium toruloides: First Insight into the MAT Locus Structure of the Sporidiobolales." Eukaryotic Cell 7, no. 6 (April 11, 2008): 1053–61. http://dx.doi.org/10.1128/ec.00025-08.
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ABSTRACT Rhodosporidium toruloides is a heterothallic, bipolar, red yeast that belongs to the Sporidiobolales, an order within a major lineage of basidiomycetes, the Pucciniomycotina. In contrast to other basidiomycetes, considerably less is known about the nature of the mating type (MAT) loci that control sexual reproduction in this lineage. Three genes (RHA1, RHA2, and RHA3) encoding precursors of the MAT A1 pheromone (rhodotorucine A) were previously identified and formed the basis for a genome walking approach that led to the identification of additional MAT genes in complementary mating strains of R. toruloides. Two mating type-specific alleles encoding a p21-activated kinase (PAK; Ste20 homolog) were found between the RHA2 and RHA3 genes, and identification in MAT A2 strains of a gene encoding a presumptive pheromone precursor enabled prediction of the structure of rhodotorucine a. In addition, a putative pheromone receptor gene (STE3 homolog) was identified upstream of RHA1. Analyses of genomic data from two closely related species, Sporobolomyces roseus and Sporidiobolus salmonicolor, identified syntenic regions that contain homologs of all the above-mentioned genes. Notably, six novel pheromone precursor genes were uncovered, which encoded, similarly to the RHA genes, multiple tandem copies of the peptide moiety. This suggests that this structure, which is unique among fungal lipopeptide pheromones, seems to be prevalent in red yeasts. Species comparisons provided evidence for a large, multigenic MAT locus structure in the Sporidiobolales, but no putative homeodomain transcription factor genes (which are present in all basidiomycetous MAT loci characterized thus far) could be found in any of the three species in the vicinity of the MAT genes identified.
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Liu, FeiFei, Seonju Marincowitz, ShuaiFei Chen, Michael Mbenoun, Panaghiotis Tsopelas, Nikoleta Soulioti, and Michael J. Wingfield. "Novel species of Huntiella from naturally-occurring forest trees in Greece and South Africa." MycoKeys 69 (June 9, 2020): 33–52. http://dx.doi.org/10.3897/mycokeys.69.53205.
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Huntiella species are wood-infecting, filamentous ascomycetes that occur in fresh wounds on a wide variety of tree species. These fungi are mainly known as saprobes although some have been associated with disease symptoms. Six fungal isolates with typical culture characteristics of Huntiella spp. were collected from wounds on native forest trees in Greece and South Africa. The aim of this study was to identify these isolates, using morphological characters and multigene phylogenies of the rRNA internal transcribed spacer (ITS) region, portions of the β-tubulin (BT1) and translation elongation factor 1α (TEF-1α) genes. The mating strategies of these fungi were also determined through PCR amplification of mating type genes. The study revealed two new species; one from Platanus orientalis in Greece and one from Colophospermum mopane and Senegalia nigrescens in South Africa. These novel taxa have been provided with the names, H. hellenicasp. nov. and H. krugerisp. nov., respectively. The former species was found to have a homothallic and the latter a heterothallic mating system.
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Coppin, Evelyne, Christelle de Renty, and Robert Debuchy. "The Function of the Coding Sequences for the Putative Pheromone Precursors in Podospora anserina Is Restricted to Fertilization." Eukaryotic Cell 4, no. 2 (February 2005): 407–20. http://dx.doi.org/10.1128/ec.4.2.407-420.2005.
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ABSTRACT We cloned the pheromone precursor genes of Podospora anserina in order to elucidate their role in the biology of this fungus. The mfp gene encodes a 24-amino-acid polypeptide finished by the CAAX motif, characteristic of fungal lipopeptide pheromone precursors similar to the a-factor precursor of Saccharomyces cerevisiae. The mfm gene encodes a 221-amino-acid polypeptide, which is related to the S. cerevisiae α-factor precursor and contains two 13-residue repeats assumed to correspond to the mature pheromone. We deleted the mfp and mfm coding sequence by gene replacement. The mutations specifically affect male fertility, without impairing female fertility and vegetative growth. The male defect is mating type specific: the mat + Δmfp and mat− Δmfm mutants produce male cells inactive in fertilization whereas the mat− Δmfp and mat + Δmfm mutants show normal male fertility. Genetic data indicate that both mfp and mfm are transcribed at a low level in mat + and mat− vegetative hyphae. Northern-blot analysis shows that their transcription is induced by the mating types in microconidia (mfp by mat + and mfm by mat−). We managed to cross Δmfp Δmfm strains of opposite mating type, by complementation and transient expression of the pheromone precursor gene to trigger fertilization. These crosses were fertile, demonstrating that once fertilization occurs, the pheromone precursor genes are unnecessary for the completion of the sexual cycle. Finally, we show that the constitutively transcribed gpd::mfm and gpd::mfp constructs are repressed at a posttranscriptional level by the noncognate mating type.
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Yue, Changli, Lora M. Cavallo, J. Andrew Alspaugh, Ping Wang, Gary M. Cox, John R. Perfect, and Joseph Heitman. "The STE12α Homolog Is Required for Haploid Filamentation But Largely Dispensable for Mating and Virulence in Cryptococcus neoformans." Genetics 153, no. 4 (December 1, 1999): 1601–15. http://dx.doi.org/10.1093/genetics/153.4.1601.
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Abstract Cryptococcus neoformans is a fungal pathogen that causes meningitis in immunocompromised hosts. The organism has a known sexual cycle, and strains of the MATα mating type are more virulent than isogenic MATa strains in mice, and they are more common in the environment and infected hosts. A C. neoformans homolog of the STE12 transcription factor that regulates mating, filamentation, and virulence in Saccharomyces cerevisiae and Candida albicans was identified previously, found to be encoded by a novel region of the MATα mating type locus, and shown to enhance filamentous growth when overexpressed. We have disrupted the C. neoformans STE12 gene in a pathogenic serotype A isolate. ste12 mutant strains exhibit a severe defect in filamentation and sporulation (haploid fruiting) in response to nitrogen starvation. In contrast, ste12 mutant strains have only modest mating defects and are fully virulent in two animal models compared to the STE12 wild-type strain. In genetic epistasis experiments, STE12 functions in a MAP kinase cascade to regulate fruiting, but not mating. Thus, the C. neoformans STE12α transcription factor homolog plays a specialized function in haploid fruiting, but it is dispensable or redundant for mating and virulence. The association of the MATα locus with virulence may involve additional genes, and other transcription factors that regulate mating and virulence remain to be identified.
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P�ggeler, Stefanie, Birgit Hoff, and Ulrich K�ck. "Asexual Cephalosporin C Producer Acremonium chrysogenum Carries a Functional Mating Type Locus." Applied and Environmental Microbiology 74, no. 19 (August 8, 2008): 6006–16. http://dx.doi.org/10.1128/aem.01188-08.
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ABSTRACT Acremonium chrysogenum, the fungal producer of the pharmaceutically relevant β-lactam antibiotic cephalosporin C, is classified as asexual because no direct observation of mating or meiosis has yet been reported. To assess the potential of A. chrysogenum for sexual reproduction, we screened an expressed sequence tag library from A. chrysogenum for the expression of mating type (MAT) genes, which are the key regulators of sexual reproduction. We identified two putative mating type genes that are homologues of the α-box domain gene, MAT1-1-1 and MAT1-1-2, encoding an HPG domain protein defined by the presence of the three invariant amino acids histidine, proline, and glycine. In addition, cDNAs encoding a putative pheromone receptor and pheromone-processing enzymes, as well as components of a pheromone response pathway, were found. Moreover, the entire A. chrysogenum MAT1-1 (AcMAT1-1) gene and regions flanking the MAT region were obtained from a genomic cosmid library, and sequence analysis revealed that in addition to AcMAT1-1-1 and AcMAT1-1-2, the AcMAT1-1 locus comprises a third mating type gene, AcMAT1-1-3, encoding a high-mobility-group domain protein. The α-box domain sequence of AcMAT1-1-1 was used to determine the phylogenetic relationships of A. chrysogenum to other ascomycetes. To determine the functionality of the AcMAT1-1 locus, the entire MAT locus was transferred into a MAT deletion strain of the heterothallic ascomycete Podospora anserina (the PaΔMAT strain). After fertilization with a P. anserina MAT1-2 (MAT+) strain, the corresponding transformants developed fruiting bodies with mature ascospores. Thus, the results of our functional analysis of the AcMAT1-1 locus provide strong evidence to hypothesize a sexual cycle in A. chrysogenum.
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Hsueh, Yen-Ping, James A. Fraser, and Joseph Heitman. "Transitions in Sexuality: Recapitulation of an Ancestral Tri- and Tetrapolar Mating System in Cryptococcus neoformans." Eukaryotic Cell 7, no. 10 (August 22, 2008): 1847–55. http://dx.doi.org/10.1128/ec.00271-08.
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ABSTRACT Sex is orchestrated by the mating-type locus (MAT) in fungi and by sex chromosomes in plants and animals. In fungi, two patterns of sexuality occur: bipolar with a single, typically biallelic sex determinant that promotes inbreeding, and tetrapolar with two unlinked, often multiallelic sex determinants that restrict inbreeding. Multiallelism in either bipolar or tetrapolar mating systems promotes outcrossing. Cryptococcus neoformans is a pathogenic bipolar yeast with two unusually large MAT alleles (a/α) spanning >100 kb, ∼100-fold larger than many other fungal MAT loci. Based on comparative genomic analysis, this unusual MAT locus is hypothesized to have evolved from an ancestral tetrapolar system. In this model, the unlinked homeodomain (HD) transcription factor and pheromone/receptor tetrapolar loci acquired additional sex-related genes and then fused via chromosomal translocation, forming an intermediate transitional mating system (which we term tripolar), which then underwent recombination and gene conversion to fashion the extant bipolar MAT alleles. To experimentally validate this model, C. neoformans was engineered to have a tetrapolar mating system by relocating the MAT SXI1α and SXI2 a HD genes to an unlinked genomic locale. Genetic and molecular analyses revealed that this modified organism could complete a tetrapolar sexual cycle. Analysis of progeny generated from bipolar, tripolar, and tetrapolar crosses provides direct experimental evidence that the tripolar state confers decreased fertility and therefore may represent an unstable evolutionary intermediate. These findings illustrate how transitions between outcrossing and inbreeding preference occur by involving sex determinant linkage and collapse from multiallelic to biallelic sex determination, providing insights into both fungal sex evolution and early steps in sex chromosome evolution.
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Kües, Ursula. "Life History and Developmental Processes in the Basidiomycete Coprinus cinereus." Microbiology and Molecular Biology Reviews 64, no. 2 (June 1, 2000): 316–53. http://dx.doi.org/10.1128/mmbr.64.2.316-353.2000.
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SUMMARY Coprinus cinereus has two main types of mycelia, the asexual monokaryon and the sexual dikaryon, formed by fusion of compatible monokaryons. Syngamy (plasmogamy) and karyogamy are spatially and temporally separated, which is typical for basidiomycetous fungi. This property of the dikaryon enables an easy exchange of nuclear partners in further dikaryotic-monokaryotic and dikaryotic-dikaryotic mycelial fusions. Fruiting bodies normally develop on the dikaryon, and the cytological process of fruiting-body development has been described in its principles. Within the specialized basidia, present within the gills of the fruiting bodies, karyogamy occurs in a synchronized manner. It is directly followed by meiosis and by the production of the meiotic basidiospores. The synchrony of karyogamy and meiosis has made the fungus a classical object to study meiotic cytology and recombination. Several genes involved in these processes have been identified. Both monokaryons and dikaryons can form multicellular resting bodies (sclerotia) and different types of mitotic spores, the small uninucleate aerial oidia, and, within submerged mycelium, the large thick-walled chlamydospores. The decision about whether a structure will be formed is made on the basis of environmental signals (light, temperature, humidity, and nutrients). Of the intrinsic factors that control development, the products of the two mating type loci are most important. Mutant complementation and PCR approaches identified further genes which possibly link the two mating-type pathways with each other and with nutritional regulation, for example with the cAMP signaling pathway. Among genes specifically expressed within the fruiting body are those for two galectins, β-galactoside binding lectins that probably act in hyphal aggregation. These genes serve as molecular markers to study development in wild-type and mutant strains. The isolation of genes for potential non-DNA methyltransferases, needed for tissue formation within the fruiting body, promises the discovery of new signaling pathways, possibly involving secondary fungal metabolites.
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Yee, A. R., and J. W. Kronstad. "Dual Sets of Chimeric Alleles Identify Specificity Sequences for the bE and bW Mating and Pathogenicity Genes of Ustilago maydis." Molecular and Cellular Biology 18, no. 1 (January 1, 1998): 221–32. http://dx.doi.org/10.1128/mcb.18.1.221.
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ABSTRACT The b mating-type locus of the fungal plant pathogenUstilago maydis encodes two multiallelic gene products, bE and bW, that control the formation and maintenance of the infectious cell type. Dimerization via the N-terminal regions of bE and bW proteins encoded by alleles of different specificities establishes a homeodomain-containing transcription factor. The bE and bW products encoded by alleles of like specificities fail to dimerize. We constructed sets of chimeric alleles for the bE1 andbE2 genes and for the bW1 and bW2genes to identify sequences that control specificity. The mating behavior of strains carrying chimeric alleles identified three classes of specificity: b2 (class I), specificity different from either parental type (class II), and b1 (class III). Crosses between strains carrying bE and bWchimeric alleles identified two short blocks of amino acids that influence specificity and that are located in the N-terminal variable regions of the b proteins. Comparisons of pairs of chimeric alleles encoding polypeptides differing in specificity and differing at single amino acid positions identified 16 codon positions that influence the interaction between bE and bW. Fifteen of these positions lie within the blocks of amino acids identified by crosses between the strains carrying chimeric alleles. Overall, this work provides insight into the organization of the regions that control recognition.
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Ramírez-Zavaleta, Candy Y., Griselda E. Salas-Delgado, Alejandro De Las Peñas, and Irene Castaño. "Subtelomeric Silencing of the MTL3 Locus of Candida glabrata Requires yKu70, yKu80, and Rif1 Proteins." Eukaryotic Cell 9, no. 10 (July 30, 2010): 1602–11. http://dx.doi.org/10.1128/ec.00129-10.
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ABSTRACT Candida glabrata is a haploid opportunistic fungal pathogen that is phylogenetically related to Saccharomyces cerevisiae. Even though C. glabrata has no known sexual cycle, it contains, like S. cerevisiae, three mating type-like loci (MTL) called MTL1, MTL2, and MTL3, as well as most of the genes required for mating, meiosis, and sporulation. MTL1 is localized at an internal position on chromosome B and is thought to be the locus corresponding to the MAT locus in S. cerevisiae. MTL2 and MTL3 are localized close to two telomeres on different chromosomes (29.4 kb from Chr E-L and 10.5 kb from Chr B-L, respectively). By using URA3 reporter gene insertions at the three MTL loci, we found that in contrast to the case for S. cerevisiae, only MTL3 is subject to transcriptional silencing while MTL2 is transcriptionally active, and this is in agreement with previously reported data. We found that the silencing of MTL3 is nucleated primarily at the left telomere of chromosome B and spreads over 12 kb to MTL3, rather than nucleating at flanking, closely positioned cis-acting silencers, like those flanking HMR and HML of S. cerevisiae. Interestingly, the silencing of MTL3 absolutely requires the yKu70, yKu80, and Rif1 proteins, in sharp contrast to the silencing of the HM loci of S. cerevisiae. In addition, we found that several cell type-specific genes are expressed in C. glabrata regardless of the presence, or even absence, of mating type information at any of the MTL loci.
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Panwar, Sneh L., Melanie Legrand, Daniel Dignard, Malcolm Whiteway, and Paul T. Magee. "MFα1, the Gene Encoding the α Mating Pheromone of Candida albicans." Eukaryotic Cell 2, no. 6 (December 2003): 1350–60. http://dx.doi.org/10.1128/ec.2.6.1350-1360.2003.
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ABSTRACT Candida albicans, the single most frequently isolated human fungal pathogen, was thought to be asexual until the recent discovery of the mating-type-like locus (MTL). Homozygous MTL strains were constructed and shown to mate. Furthermore, it has been demonstrated that opaque-phase cells are more efficient in mating than white-phase cells. The similarity of the genes involved in the mating pathway in Saccharomyces cerevisiae and C. albicans includes at least one gene (KEX2) that is involved in the processing of the α mating pheromone in the two yeasts. Taking into account this similarity, we searched the C. albicans genome for sequences that would encode the α pheromone gene. Here we report the isolation and characterization of the gene MFα1, which codes for the precursor of the α mating pheromone in C. albicans. Two active α-peptides, 13 and 14 amino acids long, would be generated after the precursor molecule is processed in C. albicans. To examine the role of this gene in mating, we constructed an mfα1 null mutant of C. albicans. The mfα1 null mutant fails to mate as MTLα, while MTLa mfα1 cells are still mating competent. Experiments performed with the synthetic α-peptides show that they are capable of inducing growth arrest, as demonstrated by halo tests, and also induce shmooing in MTLa cells of C. albicans. These peptides are also able to complement the mating defect of an MTLα kex2 mutant strain when added exogenously, thereby confirming their roles as α mating pheromones.
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Xu, Jin-rong, and John F. Leslie. "A Genetic Map of Gibberella fujikuroi Mating Population A (Fusarium moniliforme)." Genetics 143, no. 1 (May 1, 1996): 175–89. http://dx.doi.org/10.1093/genetics/143.1.175.
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Abstract We constructed a recombination-based map of the fungal plant pathogen Gibberella fujikuroi mating population A (asexual stage Fusarium moniliforme). The map is based on the segregation of 142 restriction fragment length polymorphism (RFLP) markers, two auxotrophic genes (arg1, nic1), mating type (matA+ / matA−), female sterility (ste1), spore-killer (Sk), and a gene governing the production of the mycotoxin fumonisin B1 (fum1) among 121 random ascospore progeny from a single cross. We identified 12 linkage groups corresponding to the 12 chromosome-sized DNAs previously observed in contour-clamped homogeneous electric field (CHEF) gels. Linkage groups and chromosomes were correlated via Southern blots between appropriate RFLP markers and the CHEF gels. Eleven of the 12 chromosomes are meiotically stable, but the 12th (and smallest) is subject to deletions in 3% (4/121) of the progeny. Positive chiasma interference occurred on five of the 12 chromosomes, and nine of the 12 chromosomes averaged more than one crossover per chromosome. The average kb/cM ratio in this cross is ~32.
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Ma, Li-Guo, and Yun Geng. "Determination of the reference genes for qRT-PCR normalization and expression levels of MAT genes under various conditions in Ulocladium." PeerJ 8 (November 23, 2020): e10379. http://dx.doi.org/10.7717/peerj.10379.
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The genus Ulocladium is thought to be strictly asexual. One of the possible reasons for the lack of sexuality in Ulocladium species is the absence of the stimulus of environmental factors. Sexual reproduction in ascomycetes is controlled by a specific region in the genome referred to as mating-type locus (MAT) that consists of two dissimilar DNA sequences in the mating partners, termed MAT1-1 and MAT1-2 idiomorphs. To identify the response of MAT loci to environmental conditions, the mRNA transcription level of MAT1-1-1 and MAT1-2-1 genes was tested using qRT-PCR under different temperatures (−20 °C, −10 °C, 0 °C, 10 °C, 20 °C, 30 °C and 40 °C), culture medias (CM, OA, HAY, PCA, PDA and V8), photoperiods (24 h light, 24 h dark, 12 h light/12 h dark, 10 h light/14 h dark and 8 h light/16 h dark), and CO2 concentrations (0.03%, 0.5%, 1%, 5%, 10%, 15% and 20%). For obtaining reliable results from qRT-PCR, the most stable internal control gene and optimal number of reference genes for normalization were determined under different treatments. The results showed that there is no universal internal control gene that is expressed at a constant level under different experimental treatments. In comparison to various incubation conditions, the relative expression levels of both MAT genes were significantly increased when fungal mycelia were grown on HAY culture media at 0–10 °C with a light/dark cycle, indicating that temperature, culture media, and light might be the key environmental factors for regulating the sexuality in Ulocladium. Moreover, MAT1-1-1 and MAT1-2-1 genes showed similar expression patterns under different treatments, suggesting that the two MAT genes might play an equally important role in the sexual evolutionary process.
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Gupta, Atul K., J. M. Seneviratne, G. K. Joshi, and Anil Kumar. "Induction of MAP Kinase Homologues during Growth and Morphogenetic Development of Karnal Bunt (Tilletia indica) under the Influence of Host Factor(s) from Wheat Spikes." Scientific World Journal 2012 (2012): 1–12. http://dx.doi.org/10.1100/2012/539583.
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Signaling pathways that activate different mitogen-activated protein kinases (MAPKs) in response to certain environmental conditions, play important role in mating type switching (Fus3) and pathogenicity (Pmk1) in many fungi. In order to determine the roles of such regulatory genes inTilletia indica, the causal pathogen of Karnal bunt (KB) of wheat, semi-quantitative and quantitative RT-PCR was carried out to isolate and determine the expression of MAP kinase homologues during fungal growth and development underin vitroculture. Maximum expression of TiFus3 and TiPmk1 genes were observed at 14th and 21st days of culture and decreased thereafter. To investigate whether the fungus alters the expression levels of same kinases upon interaction with plants, cultures were treated with 1% of host factors (extracted from S-2 stage of wheat spikes). Such treatment induced the expression of MAPks in time dependent manner compared to the absence of host factors. These results suggest that host factor(s) provide certain signal(s) which activate TiFus3 and TiPmk1 during morphogenetic development ofT. indica. The results also provides a clue about the role of host factors in enhancing the disease potential due to induction of MAP kinases involved in fungal development and pathogenecity.
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Wang, Zheng, Francesc Lopez-Giraldez, Nina Lehr, Marta Farré, Ralph Common, Frances Trail, and Jeffrey P. Townsend. "Global Gene Expression and Focused Knockout Analysis Reveals Genes Associated with Fungal Fruiting Body Development in Neurospora crassa." Eukaryotic Cell 13, no. 1 (November 15, 2013): 154–69. http://dx.doi.org/10.1128/ec.00248-13.
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ABSTRACTFungi can serve as highly tractable models for understanding genetic basis of sexual development in multicellular organisms. Applying a reverse-genetic approach to advance such a model, we used random and multitargeted primers to assay gene expression across perithecial development inNeurospora crassa. We found that functionally unclassified proteins accounted for most upregulated genes, whereas downregulated genes were enriched for diverse functions. Moreover, genes associated with developmental traits exhibited stage-specific peaks of expression. Expression increased significantly across sexual development for mating type genemat a-1and format A-1specific pheromone precursorccg-4. In addition, expression of a gene encoding a protein similar to zinc finger,stc1, was highly upregulated early in perithecial development, and a strain with a knockout of this gene exhibited arrest at the same developmental stage. A similar expression pattern was observed for genes in RNA silencing and signaling pathways, and strains with knockouts of these genes were also arrested at stages of perithecial development that paralleled their peak in expression. The observed stage specificity allowed us to correlate expression upregulation and developmental progression and to identify regulators of sexual development. Bayesian networks inferred from our expression data revealed previously known and new putative interactions between RNA silencing genes and pathways. Overall, our analysis provides a fine-scale transcriptomic landscape and novel inferences regarding the control of the multistage development process of sexual crossing and fruiting body development inN. crassa.
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Brenes, Lucas R., Matthew B. Lohse, Nairi Hartooni, and Alexander D. Johnson. "A Set of Diverse Genes Influence the Frequency of White-Opaque Switching in Candida albicans." G3: Genes|Genomes|Genetics 10, no. 8 (June 2, 2020): 2593–600. http://dx.doi.org/10.1534/g3.120.401249.
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The fungal species Candida albicans is both a member of the human microbiome and a fungal pathogen. C. albicans undergoes several different morphological transitions, including one called white-opaque switching. Here, cells reversibly switch between two states, “white” and “opaque,” and each state is heritable through many cell generations. Each cell type has a distinct cellular and colony morphology and they differ in many other properties including mating, nutritional specialization, and interactions with the innate immune system. Previous genetic screens to gain insight into white-opaque switching have focused on certain classes of genes (for example transcriptional regulators or chromatin modifying enzymes). In this paper, we examined 172 deletion mutants covering a broad range of cell functions. We identified 28 deletion mutants with at least a fivefold effect on switching frequencies; these cover a wide variety of functions ranging from membrane sensors to kinases to proteins of unknown function. In agreement with previous reports, we found that components of the pheromone signaling cascade affect white-to-opaque switching; however, our results suggest that the major effect of Cek1 on white-opaque switching occurs through the cell wall damage response pathway. Most of the genes we identified have not been previously implicated in white-opaque switching and serve as entry points to understand new aspects of this morphological transition.
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Young, Carolyn A., Clive H. Bock, Nikki D. Charlton, Chakradhar Mattupalli, Nick Krom, Joanna K. Bowen, Matthew Templeton, Kim M. Plummer, and Bruce W. Wood. "Evidence for Sexual Reproduction: Identification, Frequency, and Spatial Distribution of Venturia effusa (Pecan Scab) Mating Type Idiomorphs." Phytopathology® 108, no. 7 (July 2018): 837–46. http://dx.doi.org/10.1094/phyto-07-17-0233-r.
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Venturia effusa (syn. Fusicladium effusum), causal agent of pecan scab, is the most prevalent pathogen of pecan (Carya illinoinensis), causing severe yield losses in the southeastern United States. V. effusa is currently known only by its asexual (conidial) stage. However, the degree and distribution of genetic diversity observed within and among populations of V. effusa are typical of a sexually reproducing fungal pathogen, and comparable with other dothideomycetes with a known sexual stage, including the closely related apple scab pathogen, V. inaequalis. Using the mating type (MAT) idiomorphs from V. inaequalis, we identified a single MAT gene, MAT1-1-1, in a draft genome of V. effusa. The MAT1-1-1 locus is flanked by two conserved genes encoding a DNA lyase (APN2) and a hypothetical protein. The MAT locus spanning the flanking genes was amplified and sequenced from a subset of 14 isolates, of which 7 contained MAT1-1-1 and the remaining samples contained MAT1-2-1. A multiplex polymerase chain reaction screen was developed to amplify MAT1-1-1, MAT1-2-1, and a conserved reference gene encoding β-tubulin, and used to screen 784 monoconidial isolates of V. effusa collected from 11 populations of pecan across the southeastern United States. A hierarchical sampling protocol representing region, orchard, and tree allowed for analysis of MAT structure at different spatial scales. Analysis of this collection revealed the frequency of the MAT idiomorphs is in a 1:1 equilibrium of MAT1-1:MAT1-2. The apparent equilibrium of the MAT idiomorphs provides impetus for a renewed effort to search for the sexual stage of V. effusa. [Formula: see text] Copyright © 2018 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .
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Clarke, D. L., G. L. Woodlee, C. M. McClelland, T. S. Seymour, and B. L. Wickes. "The Cryptococcus neoformans STE11α gene is similar to other fungal mitogen-activated protein kinase kinase kinase (MAPKKK) genes but is mating type specific." Molecular Microbiology 40, no. 1 (December 21, 2001): 200–213. http://dx.doi.org/10.1046/j.1365-2958.2001.02375.x.
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Idnurm, Alexander. "Sex Determination in the First-Described Sexual Fungus." Eukaryotic Cell 10, no. 11 (September 9, 2011): 1485–91. http://dx.doi.org/10.1128/ec.05149-11.
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ABSTRACTThe original report of sex in fungi dates 2 centuries ago to the speciesSyzygites megalocarpus(Mucoromycotina). The organism was subsequently used in 1904 to represent self-fertile homothallic species when the concepts of heterothallism and homothallism were developed for the fungal kingdom. In this study, two putativesex/MATloci were identified in individual strains ofS. megalocarpus, accounting for its homothallic behavior. The strains encode both of the high-mobility-group domain-containing proteins, SexM and SexP, flanked by RNA helicase and glutathione oxidoreductase genes that are found adjacent to the mating-type loci in other Mucoromycotina species. The presence of pseudogenes and the arrangement of genes suggest that the origin of homothallism in this species is from a heterothallic relative, obtained via a chromosomal rearrangement to switch two alleles into two separated loci within a single genetic background. Similar events have given rise to homothallic species from heterothallic species in ascomycete fungi, demonstrating that conserved forces shape the evolution of sex determination and speciation in highly diverged fungi.
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Sun, Sheng, Ci Fu, Giuseppe Ianiri, and Joseph Heitman. "The Pheromone and Pheromone Receptor Mating-Type Locus Is Involved in Controlling Uniparental Mitochondrial Inheritance in Cryptococcus." Genetics 214, no. 3 (December 30, 2019): 703–17. http://dx.doi.org/10.1534/genetics.119.302824.
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Mitochondria are inherited uniparentally during sexual reproduction in the majority of eukaryotic species studied, including humans, mice, and nematodes, as well as many fungal species. Mitochondrial uniparental inheritance (mito-UPI) could be beneficial in that it avoids possible genetic conflicts between organelles with different genetic backgrounds, as recently shown in mice, and it could prevent the spread of selfish genetic elements in the mitochondrial genome. Despite the prevalence of observed mito-UPI, the underlying mechanisms and the genes involved in controlling this non-Mendelian inheritance are poorly understood in many species. In Cryptococcus neoformans, a human pathogenic basidiomyceteous fungus, mating types (MATα and MATa) are defined by alternate alleles at the single MAT locus that evolved from fusion of the two MAT loci (P/R encoding pheromones and pheromone receptors, and HD encoding homeodomain transcription factors) that are the ancestral state in the basidiomycota. Mitochondria are inherited uniparentally from the MATa parent in C. neoformans, and this requires the SXI1α and SXI2a HD factors encoded by MAT. However, there is evidence that additional genes contribute to the control of mito-UPI in Cryptococcus. Here, we show that in C. amylolentus, a sibling species of C. neoformans with unlinked P/R and HD MAT loci, mito-UPI is controlled by the P/R locus and is independent of the HD locus. Consistently, by replacing the MATα alleles of the pheromones (MF) and pheromone receptor (STE3) with the MATa alleles, we show that these P/R locus-defining genes indeed affect mito-UPI in C. neoformans during sexual reproduction. Additionally, we show that during early stages of C. neoformans sexual reproduction, conjugation tubes are always produced by the MATα cells, resulting in unidirectional migration of the MATα nucleus into the MATa cell during zygote formation. This process is controlled by the P/R locus and could serve to physically restrict movement of MATα mitochondria in the zygotes, and thereby contribute to mito-UPI. We propose a model in which both physical and genetic mechanisms function in concert to prevent the coexistence of mitochondria from the two parents in the zygote, and subsequently in the meiotic progeny, thus ensuring mito-UPI in pathogenic Cryptococcus, as well as in closely related nonpathogenic species. The implications of these findings are discussed in the context of the evolution of mito-UPI in fungi and other more diverse eukaryotes.
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Larraya, Luis M., Kylie J. Boyce, Austin So, Barbara R. Steen, Steven Jones, Marco Marra, and James W. Kronstad. "Serial Analysis of Gene Expression Reveals Conserved Links between Protein Kinase A, Ribosome Biogenesis, and Phosphate Metabolism in Ustilago maydis." Eukaryotic Cell 4, no. 12 (December 2005): 2029–43. http://dx.doi.org/10.1128/ec.4.12.2029-2043.2005.
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ABSTRACT The switch from budding to filamentous growth is a key aspect of invasive growth and virulence for the fungal phytopathogen Ustilago maydis. The cyclic AMP (cAMP) signaling pathway regulates dimorphism in U. maydis, as demonstrated by the phenotypes of mutants with defects in protein kinase A (PKA). Specifically, a mutant lacking the regulatory subunit of PKA encoded by the ubc1 gene displays a multiple-budded phenotype and fails to incite disease symptoms, although proliferation does occur in the plant host. A mutant with a defect in a catalytic subunit of PKA, encoded by adr1, has a constitutively filamentous phenotype and is nonpathogenic. We employed serial analysis of gene expression to examine the transcriptomes of a wild-type strain and the ubc1 and adr1 mutants to further define the role of PKA in U. maydis. The mutants displayed changes in the transcript levels for genes encoding ribosomal proteins, genes regulated by the b mating-type proteins, and genes for metabolic functions. Importantly, the ubc1 mutant displayed elevated transcript levels for genes involved in phosphate acquisition and storage, thus revealing a connection between cAMP and phosphate metabolism. Further experimentation indicated a phosphate storage defect and elevated acid phosphatase activity for the ubc1 mutant. Elevated phosphate levels in culture media also enhanced the filamentous growth of wild-type cells in response to lipids, a finding consistent with PKA regulation of morphogenesis in U. maydis. Overall, these findings extend our understanding of cAMP signaling in U. maydis and reveal a link between phosphate metabolism and morphogenesis.
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Tang, Robin J., Julia Breger, Alexander Idnurm, Kimberly J. Gerik, Jennifer K. Lodge, Joseph Heitman, Stephen B. Calderwood, and Eleftherios Mylonakis. "Cryptococcus neoformans Gene Involved in Mammalian Pathogenesis Identified by a Caenorhabditis elegans Progeny-Based Approach." Infection and Immunity 73, no. 12 (December 2005): 8219–25. http://dx.doi.org/10.1128/iai.73.12.8219-8225.2005.
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ABSTRACT Caenorhabditis elegans can serve as a substitute host for the study of microbial pathogenesis. We found that mutations in genes of the fungal pathogen Cryptococcus neoformans involved in mammalian virulence allow C. elegans to produce greater numbers of progeny than when exposed to wild-type fungus. We used this property to screen a library of C. neoformans mutants for strains that permit larger C. elegans brood sizes. In this screen, we identified a gene homologous to Saccharomyces cerevisiae ROM2. C. neoformans rom2 mutation resulted in a defect in mating and growth defects at elevated temperature or in the presence of cell wall or hyperosmolar stresses. An effect of the C. neoformans rom2 mutation in virulence was confirmed in a murine inhalation infection model. We propose that a screen for progeny-permissive mutants of microorganisms can serve as a high-throughput method for identifying novel loci related to mammalian pathogenesis.
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Dorrity, Michael W., Josh T. Cuperus, Jolie A. Carlisle, Stanley Fields, and Christine Queitsch. "Preferences in a trait decision determined by transcription factor variants." Proceedings of the National Academy of Sciences 115, no. 34 (August 1, 2018): E7997—E8006. http://dx.doi.org/10.1073/pnas.1805882115.
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Few mechanisms are known that explain how transcription factors can adjust phenotypic outputs to accommodate differing environments. In Saccharomyces cerevisiae, the decision to mate or invade relies on environmental cues that converge on a shared transcription factor, Ste12. Specificity toward invasion occurs via Ste12 binding cooperatively with the cofactor Tec1. Here, we determine the range of phenotypic outputs (mating vs. invasion) of thousands of DNA-binding domain variants in Ste12 to understand how preference for invasion may arise. We find that single amino acid changes in the DNA-binding domain can shift the preference of yeast toward either mating or invasion. These mutations define two distinct regions of this domain, suggesting alternative modes of DNA binding for each trait. We characterize the DNA-binding specificity of wild-type Ste12 to identify a strong preference for spacing and orientation of both homodimeric and heterodimeric sites. Ste12 mutants that promote hyperinvasion in a Tec1-independent manner fail to bind cooperative sites with Tec1 and bind to unusual dimeric Ste12 sites composed of one near-perfect and one highly degenerate site. We propose a model in which Ste12 alone may have evolved to activate invasion genes, which could explain how preference for invasion arose in the many fungal pathogens that lack Tec1.
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Staniszewska, Monika. "Virulence Factors in Candida species." Current Protein & Peptide Science 21, no. 3 (March 26, 2020): 313–23. http://dx.doi.org/10.2174/1389203720666190722152415.
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: Fungal diseases are severe and have very high morbidity as well as up to 60% mortality for patients diagnosed with invasive fungal infection. In this review, in vitro and in vivo studies provided us with the insight into the role of Candida virulence factors that mediate their success as pathogens, such as: membrane and cell wall (CW) barriers, dimorphism, biofilm formation, signal transduction pathway, proteins related to stress tolerance, hydrolytic enzymes (e.g. proteases, lipases, haemolysins), and toxin production. The review characterized the virulence of clinically important C. albicans, C. parapsilosis, C. tropicalis, C. glabrata and C. krusei. Due to the white-opaque transition in the mating-type locus MTL-homozygous cells, C. albicans demonstrates an advantage over other less related species of Candida as a human commensal and pathogen. It was reviewed that Candida ergosterol biosynthesis genes play a role in cellular stress and are essential for Candida pathogenesis both in invasive and superficial infections. Hydrolases associated with CW are involved in the host-pathogen interactions. Adhesins are crucial in colonization and biofilm formation, an important virulence factor for candidiasis. Calcineurin is involved in membrane and CW stress as well as virulence. The hyphae-specific toxin, named candidalysin, invades mucosal cells facilitating fungal invasion into deeper tissues. Expression of this protein promotes resistance to neutrophil killing in candidiasis. The virulence factors provide immunostimulatory factors, activating dendric cells and promoting T cell infiltration and activation. Targeting virulence factors, can reduce the risk of resistance development in Candida infections.
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Hull, Christina M., Marie-Josee Boily, and Joseph Heitman. "Sex-Specific Homeodomain Proteins Sxi1α and Sxi2a Coordinately Regulate Sexual Development in Cryptococcus neoformans." Eukaryotic Cell 4, no. 3 (March 2005): 526–35. http://dx.doi.org/10.1128/ec.4.3.526-535.2005.
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ABSTRACT Homeodomain proteins are central regulators of development in eukaryotes. In fungi, homeodomain proteins have been shown to control cell identity and sexual development. Cryptococcus neoformans is a human fungal pathogen with a defined sexual cycle that produces spores, the suspected infectious particles. Previously, only a single homeodomain regulatory protein involved in sexual development, Sxi1α, had been identified. Here we present the discovery of Sxi2a, a predicted but heretofore elusive cell-type-specific homeodomain protein essential for the regulation of sexual development. Our studies reveal that Sxi2a is necessary for proper sexual development and sufficient to drive this development in otherwise haploid α cells. We further show that Sxi1α and Sxi2a interact with one another and impart similar expression patterns for two key mating genes. The discovery of Sxi2a and its relationship with Sxi1α leads to a new model for how the sexual cycle is controlled in C. neoformans, with implications for virulence.
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Fan, Weihua, Peter R. Kraus, Marie-Josee Boily, and Joseph Heitman. "Cryptococcus neoformans Gene Expression during Murine Macrophage Infection." Eukaryotic Cell 4, no. 8 (August 2005): 1420–33. http://dx.doi.org/10.1128/ec.4.8.1420-1433.2005.
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ABSTRACT The fungal pathogen Cryptococcus neoformans survives phagocytosis by macrophages and proliferates within, ultimately establishing latent infection as a facultative intracellular pathogen that can escape macrophage control to cause disseminated disease. This process is hypothesized to be important for C. neoformans pathogenesis; however, it is poorly understood how C. neoformans adapts to and overcomes the hostile intracellular environment of the macrophage. Using DNA microarray technology, we have investigated the transcriptional response of C. neoformans to phagocytosis by murine macrophages. The expression profiles of several genes were verified using quantitative reverse transcription-PCR and a green fluorescent protein reporter strain. Multiple membrane transporters for hexoses, amino acids, and iron were up-regulated, as well as genes involved in responses to oxidative stress. Genes involved in autophagy, peroxisome function, and lipid metabolism were also induced. Interestingly, almost the entire mating type locus displayed increased expression 24 h after internalization, suggesting an intrinsic connection between infection and the MAT locus. Genes in the Gpa1-cyclic AMP-protein kinase A pathway were also up-regulated. Both gpa1 and pka1 mutants were found to be compromised in macrophage infection, confirming the important role of this virulence pathway. A large proportion of the repressed genes are involved in ribosome-related functions, rRNA processing, and translation initiation/elongation, implicating a reduction in translation as a central response to phagocytosis. In summary, this gene expression profile allows us to interpret the adaptation of C. neoformans to the intracellular infection process and informs the search for genes encoding novel virulence attributes.
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Swilaiman, Sameira S., Céline M. O'Gorman, S. Arunmozhi Balajee, and Paul S. Dyer. "Discovery of a Sexual Cycle in Aspergillus lentulus, a Close Relative of A. fumigatus." Eukaryotic Cell 12, no. 7 (May 6, 2013): 962–69. http://dx.doi.org/10.1128/ec.00040-13.
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ABSTRACT Aspergillus lentulus was described in 2005 as a new species within the A. fumigatus sensu lato complex. It is an opportunistic human pathogen causing invasive aspergillosis with high mortality rates, and it has been isolated from clinical and environmental sources. The species is morphologically nearly identical to A. fumigatus sensu stricto, and this similarity has resulted in their frequent misidentification. Comparative studies show that A. lentulus has some distinguishing growth features and decreased in vitro susceptibility to several antifungal agents, including amphotericin B and caspofungin. Similar to the once-presumed-asexual A. fumigatus , it has only been known to reproduce mitotically. However, we now show that A. lentulus has a heterothallic sexual breeding system. A PCR-based mating-type diagnostic detected isolates of either the MAT1-1 or MAT1-2 genotype, and examination of 26 worldwide clinical and environmental isolates revealed similar ratios of the two mating types (38% versus 62%, respectively). MAT1-1 and MAT1-2 idiomorph regions were analyzed, revealing the presence of characteristic alpha and high-mobility-group (HMG) domain genes, together with other more unusual features such as a MAT1-2-4 gene. We then demonstrated that A. lentulus possesses a functional sexual cycle with mature cleistothecia, containing heat-resistant ascospores, being produced after 3 weeks of incubation. Recombination was confirmed using molecular markers. However, isolates of A. lentulus failed to cross with highly fertile strains of A. fumigatus , demonstrating reproductive isolation between these sibling species. The discovery of the A. lentulus sexual stage has significant implications for the management of drug resistance and control of invasive aspergillosis associated with this emerging fungal pathogen.
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Borneman, Anthony R., Michael J. Hynes, and Alex Andrianopoulos. "An STE12 Homolog From the Asexual, Dimorphic Fungus Penicillium marneffei Complements the Defect in Sexual Development of an Aspergillus nidulans steA Mutant." Genetics 157, no. 3 (March 1, 2001): 1003–14. http://dx.doi.org/10.1093/genetics/157.3.1003.
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Abstract Penicillium marneffei is an opportunistic fungal pathogen of humans and the only dimorphic species identified in its genus. At 25° P. marneffei exhibits true filamentous growth, while at 37° P. marneffei undergoes a dimorphic transition to produce uninucleate yeast cells that divide by fission. Members of the STE12 family of regulators are involved in controlling mating and yeast-hyphal transitions in a number of fungi. We have cloned a homolog of the S. cerevisiae STE12 gene from P. marneffei, stlA, which is highly conserved. The stlA gene, along with the A. nidulans steA and Cryptococcus neoformans STE12α genes, form a distinct subclass of STE12 homologs that have a C2H2 zinc-finger motif in addition to the homeobox domain that defines STE12 genes. To examine the function of stlA in P. marneffei, we isolated a number of mutants in the P. marneffei-type strain and, in combination with selectable markers, developed a highly efficient DNA-mediated transformation procedure and gene deletion strategy. Deletion of the stlA gene had no detectable effect on vegetative growth, asexual development, or dimorphic switching in P. marneffei. Despite the lack of a detectable function, the P. marneffei stlA gene complemented the sexual defect of an A. nidulans steA mutant. In addition, substitution rate estimates indicate that there is a significant bias against nonsynonymous substitutions. These data suggest that P. marneffei may have a previously unidentified cryptic sexual cycle.
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Liu, Wei, Yingli Cai, Qianqian Zhang, Fang Shu, Lianfu Chen, Xiaolong Ma, and Yinbing Bian. "Subchromosome-Scale Nuclear and Complete Mitochondrial Genome Characteristics of Morchella crassipes." International Journal of Molecular Sciences 21, no. 2 (January 12, 2020): 483. http://dx.doi.org/10.3390/ijms21020483.
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Morchella crassipes (Vent.) Pers., a typical yellow morel species with high economic value, is mainly distributed in the low altitude plains of Eurasia. However, rare research has been performed on its genomics and polarity, thus limiting its research and development. Here, we reported a fine physical map of the nuclear genome at the subchromosomal-scale and the complete mitochondrial genome of M. crassipes. The complete size of the nuclear genome was 56.7 Mb, and 23 scaffolds were assembled, with eight of them being complete chromosomes. A total of 11,565 encoding proteins were predicted. The divergence time analysis showed that M. crassipes representing yellow morels differentiated with black morels at ~33.98 Mya (million years), with 150 gene families contracted and expanded in M. crassipes versus the two black morels (M. snyderi and M. importuna). Furthermore, 409 CAZYme genes were annotated in M. crassipes, containing almost all plant cell wall degrading enzymes compared with the mycorrhizal fungi (truffles). Genomic annotation of mating type loci and amplification of the mating genes in the monospore population was conducted, the results indicated that M. crassipes is a heterothallic fungus. Additionally, a complete circular mitochondrial genome of M. crassipes was assembled, the size reached as large as 531,195 bp. It can be observed that the strikingly large size was the biggest up till now, coupled with 14 core conserved mitochondrial protein-coding genes, two rRNAs, 31 tRNAs, 51 introns, and 412 ncORFs. The total length of intron sequences accounted for 53.67% of the mitochondrial genome, with 19 introns having a length over 5 kb. Particularly, 221 of 412 ncORFs were distributed within 51 introns, and the total length of the ncORFs sequence accounted for 40.83% of the mitochondrial genome, and 297 ncORFs had expression activity in the mycelium stage, suggesting their potential functions in M. crassipes. Meanwhile, there was a high degree of repetition (51.31%) in the mitochondria of M. crassipes. Thus, the large number of introns, ncORFs and internal repeat sequences may contribute jointly to the largest fungal mitochondrial genome to date. The fine physical maps of nuclear genome and mitochondrial genome obtained in this study will open a new door for better understanding of the mysterious species of M. crassipes.
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Mould, Michael J. R., Tao Xu, Mary Barbara, Norman N. Iscove, and Michèle C. Heath. "cDNAs Generated from Individual Epidermal Cells Reveal that Differential Gene Expression Predicting Subsequent Resistance or Susceptibility to Rust Fungal Infection Occurs Prior to the Fungus Entering the Cell Lumen." Molecular Plant-Microbe Interactions® 16, no. 9 (September 2003): 835–45. http://dx.doi.org/10.1094/mpmi.2003.16.9.835.
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As the cowpea rust fungus penetrates the wall of a cowpea epidermal cell, resistant and susceptible plants exhibit different ultrastructural and cytochemical changes within the epidermal protoplast. To examine plant gene expression at this stage of infection, cytoplasm was extracted from individual inoculated or uninoculated epidermal cells before the fungal penetration peg reached the cell lumen. Initial differential colony hybridization screening of an expressed sequence tag library constructed from globally amplified cDNAs generated from the inoculated resistant cells resulted in 80 clones (out of 835) with a differential hybridization pattern. Further slot-blot screening and screening of the amplified cDNAs generated from inoculated or uninoculated, resistant or susceptible cells revealed 28 separate genes, mostly with no matching sequences in the databases, that were up-regulated in response to the growth of the fungus through the wall of resistant or susceptible cells. Five genes, including those coding for β- and α-tubulin, were found to be down-regulated specifically in inoculated, susceptible cells, and five were specifically up-regulated in inoculated, resistant cells, including a PR-10 homolog and a phenylalanine ammonialyase gene. Probing the amplified cDNAs from each cell type for the expression of cell death-related genes revealed that an LLS1 homolog (vuLLS1), cloned from cowpea, was up-regulated by infection in both resistant and susceptible cells and that a homolog of HSR203J was differentially up-regulated in resistant cells. These data show that changes in gene expression predicting the subsequent expression of susceptibility or hypersensitive resistance to fungal infection occur prior to the fungus entering the cell lumen.
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Fraser, James A., and Joseph Heitman. "Fungal mating-type loci." Current Biology 13, no. 20 (October 2003): R792—R795. http://dx.doi.org/10.1016/j.cub.2003.09.046.
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Boyce, Kylie J., Matthias Kretschmer, and James W. Kronstad. "The vtc4 Gene Influences Polyphosphate Storage, Morphogenesis, and Virulence in the Maize Pathogen Ustilago maydis." Eukaryotic Cell 5, no. 8 (August 2006): 1399–409. http://dx.doi.org/10.1128/ec.00131-06.
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ABSTRACT The maize pathogen Ustilago maydis switches from budding to filamentous, dikaryotic growth in response to environmental signals including nutrient status, growth in the host, and the presence of mating pheromones. The filamentous dikaryon is capable of proliferating within host tissue to cause disease symptoms including tumors. The transition from yeast cells to hyphal filaments is regulated by a mitogen-activated protein kinase cascade and a cyclic-AMP-protein kinase A (PKA) pathway. Serial analysis of gene expression with PKA mutants identified orthologs of components of the PHO phosphate acquisition pathway as transcriptional targets of the PKA pathway, and these included genes for Pho84, an acid phosphatase, and the vacuolar transport chaperones Vtc1 and Vtc4. In Saccharomyces cerevisiae, Vtc4p is required during the fusion of inorganic-phosphate-containing vesicles to the vacuolar membrane and the consequent accumulation of phosphate stored as polyphosphate (polyP) in the vacuole. We found that deletion of vtc4 in U. maydis also reduced polyP stored in vacuoles. Intriguingly, Δvtc4 mutants possessed a filamentous cellular morphology, in contrast to the budding, yeast-like growth of the wild-type parent. The Δvtc4 mutants also displayed decreased symptom development and reduced proliferation in planta. The interaction with PKA signaling was further investigated by the generation of Δvtc4 ubc1 double mutants. Deletion of vtc4 completely suppressed the multiple-budded phenotype of a Δubc1 mutant, indicating that polyP stores are essential for this PKA-induced trait. Overall, this study reveals a novel role for PKA-regulated polyP accumulation in the control of fungal morphogenesis and virulence.
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Queloz, V., T. Wey, and O. Holdenrieder. "First Record of Dothistroma pini on Pinus nigra in Switzerland." Plant Disease 98, no. 12 (December 2014): 1744. http://dx.doi.org/10.1094/pdis-06-14-0630-pdn.
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The mitosporic ascomycetes Dothistroma septosporum s.s. (Dorog.) Morelet and D. pini Hulbary are closely related species (1) causing red band needle blight on Pinus spp. D. septosporum (teleomorph Mycosphaerella pini Rostr.) is considered as a cosmopolitan species, whereas D. pini (no teleomorph known) seems to have a more restricted distribution area. Detected in the United States on Pinus nigra for the first time, it was later found in Russia, Ukraine, Hungary, and France on different pine species (P. radiata, P. mugo, P. pallasiana) (3). In Switzerland, Dothistroma sp. (species not further determined) was recorded in 1989 for the first time and since then only damages on planted pines (mainly P. mugo and P. nigra) in urban areas were reported (R. Engesser, personal communication). In September 2012 and in April 2013, several planted mature trees and naturally regenerated young trees of P. nigra with Dothistroma needle blight were detected on a climatically mild forest site on limestone at the shore of Lake Walensee (47°07′48.0″ N, 9°13′54.4″ E, 420 m asl). In 2012, symptomatic needles were collected from the litter under one planted mature P. nigra tree and in 2013, symptomatic needles were collected from green twigs from a 2 m tall naturally regenerated P. nigra specimen. Conidiomata were frequently observed in the red bands but no conidia were detected. For fungal isolation, the surface of infected needles was shortly disinfected with 95% ethanol. The epi- and hypo-dermis covering the still closed conidiomata was removed and small tissue samples from the mesophyll (less than 0.5 mm length) were placed on malt extract agar (15 g/liter agar, 20 g/liter malt extract) amended by 50 mg/liter oxytetracycline. Conidia were observed after one year at 4°C in the resulting pure colonies (3 to 4 cm diameter on malt extract agar medium). The conidia formed by strain OH_120923_2_1_1 (KJ878557 = D. pini) were hyaline, smooth, thin-walled, 2- to 4-celled, and 31.6 (22 to 37) × 2.8 (2 to 3.5) μm. While conidial morphology of both Dothistroma species overlap, DNA was extracted and the internal transcribed spacer (ITS) region (primers ITS 1 and ITS 4) sequenced (KJ878557 to 81). From the 25 obtained ITS sequences, seven were identical with AY808275 (D. septosporum from P. radiata, South Africa, CMW 684), three were identical with AY808302 (D. pini from P. nigra, Michigan, CMW 10951), and 15 were identical with DQ926964 (D. pini from P. pallasiana, Ukraine, CMW 23767). The North American and Ukrainian D. pini sequences (AY808302 and DQ926964) showed only 1 bp difference. In addition, mating type genes were amplified using the method described by Groenewald et al. (2) for D. pini and scored using gel electrophoresis. Analyses showed that both D. pini ITS-sequence variants (e.g., KJ878557 and KJ878558) and both mating types were sometimes present in the same needle. In two cases, both mating types and ITS-sequence variants were also present within the same lesion. Interestingly, D. pini and D. septosporum were found on the same tree but not on the same needles. This is the first report of D. pini in Switzerland. Although symptoms of red band needle blight (species not determined) were repeatedly observed on this site during the last 20 years, the disease level always remained low and no tree mortality was noted. However, due to the presence of two ITS-sequence variants and both mating types, the incidence of D. pini in Switzerland deserves attention. References: (1) I. Barnes et al. Stud. Mycol. 50:551, 2004. (2) M. Groenewald et al. Phytopathology 97:825, 2007. (3) D. Piou and R. Ioos. Plant Dis. 98:841, 2014.
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ARIE, Tsutomu. "Mating Type Genes of Ascomycetes." Journal of Pesticide Science 25, no. 1 (2000): 44–50. http://dx.doi.org/10.1584/jpestics.25.44.
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