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Stauber L, Croll D, Prospero S. Temporal changes in pathogen diversity in a perennial plant-pathogen-hyperparasite system. Mol Ecol 2022; 31:2073-2088. [PMID: 35122694 PMCID: PMC9540319 DOI: 10.1111/mec.16386] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 01/26/2022] [Accepted: 01/31/2022] [Indexed: 11/27/2022]
Abstract
Hyperparasites can affect the evolution of pathosystems by influencing the stability of both pathogen and host populations. However, how pathogens of perennial hosts evolve in the presence of a hyperparasite has rarely been studied. Here, we investigated temporal changes in genetic diversity of the invasive chestnut blight pathogen Cryphonectria parasitica in the presence of its parasitic mycovirus Cryphonectria hypovirus 1 (CHV1). The virus reduces fungal virulence and represents an effective natural biocontrol agent against chestnut blight in Europe. We analysed genome‐wide diversity and CHV1 prevalence in C. parasitica populations in southern Switzerland that were sampled twice at an interval of about 30 years. Overall, we found that both pathogen population structure and CHV1 prevalence were retained over time. The results suggest that recent bottlenecks have influenced the structure of C. parasitica populations in southern Switzerland. Strong balancing selection signals were found at a single vegetative incompatibility (vic) locus, consistent with negative frequency‐dependent selection imposed by the vegetative incompatibility system. High levels of mating among related individuals (i.e., inbreeding) and genetic drift are probably at the origin of imbalanced allele ratios at vic loci and subsequently low vc type diversity. Virus infection rates were stable at ~30% over the study period and we found no significant impact of the virus on fungal population diversity. Consequently, the efficacy of CHV1‐mediated biocontrol was probably retained.
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Affiliation(s)
- Lea Stauber
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland.,Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Switzerland.,Department of Environmental Sciences, University of Basel, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Switzerland
| | - Simone Prospero
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
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Integrative Activity of Mating Loci, Environmentally Responsive Genes, and Secondary Metabolism Pathways during Sexual Development of Chaetomium globosum. mBio 2019; 10:mBio.02119-19. [PMID: 31822585 PMCID: PMC6904875 DOI: 10.1128/mbio.02119-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Fungal diversity has amazed evolutionary biologists for decades. One societally important aspect of this diversity manifests in traits that enable pathogenicity. The opportunistic pathogen Chaetomium globosum is well adapted to a high-humidity environment and produces numerous secondary metabolites that defend it from predation. Many of these chemicals can threaten human health. Understanding the phases of the C. globosum life cycle in which these products are made enables better control and even utilization of this fungus. Among its intriguing traits is that it both is self-fertile and lacks any means of propagule-based asexual reproduction. By profiling genome-wide gene expression across the process of sexual reproduction in C. globosum and comparing it to genome-wide gene expression in the model filamentous fungus N. crassa and other closely related fungi, we revealed associations among mating-type genes, sexual developmental genes, sexual incompatibility regulators, environmentally responsive genes, and secondary metabolic pathways. The origins and maintenance of the rich fungal diversity have been longstanding issues in evolutionary biology. To investigate how differences in expression regulation contribute to divergences in development and ecology among closely related species, transcriptomes were compared between Chaetomium globosum, a homothallic pathogenic fungus thriving in highly humid ecologies, and Neurospora crassa, a heterothallic postfire saprotroph. Gene expression was quantified in perithecia at nine distinct morphological stages during nearly synchronous sexual development. Unlike N. crassa, expression of all mating loci in C. globosum was highly correlated. Key regulators of the initiation of sexual development in response to light stimuli—including orthologs of N. crassasub-1, sub-1-dependent gene NCU00309, and asl-1—showed regulatory dynamics matching between C. globosum and N. crassa. Among 24 secondary metabolism gene clusters in C. globosum, 11—including the cochliodones biosynthesis cluster—exhibited highly coordinated expression across perithecial development. C. globosum exhibited coordinately upregulated expression of histidine kinases in hyperosmotic response pathways—consistent with gene expression responses to high humidity we identified in fellow pathogen Fusarium graminearum. Bayesian networks indicated that gene interactions during sexual development have diverged in concert with the capacities both to reproduce asexually and to live a self-compatible versus self-incompatible life cycle, shifting the hierarchical roles of genes associated with conidiation and heterokaryon incompatibility in N. crassa and C. globosum. This divergence supports an evolutionary history of loss of conidiation due to unfavorable combinations of heterokaryon incompatibility in homothallic species.
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Global distribution of mating types shows limited opportunities for mating across populations of fungi causing boxwood blight disease. Fungal Genet Biol 2019; 131:103246. [PMID: 31254611 DOI: 10.1016/j.fgb.2019.103246] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 05/23/2019] [Accepted: 06/19/2019] [Indexed: 01/23/2023]
Abstract
Boxwood blight is a disease threat to natural and managed landscapes worldwide. To determine mating potential of the fungi responsible for the disease, Calonectria pseudonaviculata and C. henricotiae, we characterized their mating-type (MAT) loci. Genomes of C. henricotiae, C. pseudonaviculata and two other Calonectria species (C. leucothoes, C. naviculata) were sequenced and used to design PCR tests for mating-type from 268 isolates collected from four continents. All four Calonectria species have a MAT locus that is structurally consistent with the organization found in heterothallic ascomycetes, with just one idiomorph per individual isolate. Mating type was subdivided by species: all C. henricotiae isolates possessed the MAT1-1 idiomorph, whereas all C. pseudonaviculata isolates possessed the MAT1-2 idiomorph. To determine the potential for divergence at the MAT1 locus to present a barrier to interspecific hybridization, evolutionary analysis was conducted. Phylogenomic estimates showed that C. henricotiae and C. pseudonaviculata diverged approximately 2.1 Mya. However, syntenic comparisons, phylogenetic analyses, and estimates of nucleotide divergence across the MAT1 locus and proximal genes identified minimal divergence in this region of the genome. These results show that in North America and parts of Europe, where only C. pseudonaviculata resides, mating is constrained by the absence of MAT1-1. In regions of Europe where C. henricotiae and C. pseudonaviculata currently share the same host and geographic range, it remains to be determined whether or not these two recently diverged species are able to overcome species barriers to mate.
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Affiliation(s)
- Kerry O'Donnell
- Microbial Properties Research Unit, National Center for Agricultural Utilization Research, United States Department of Agriculture, Agricultural Research Service, Peoria, Illinois 61604-3999
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Vaillancourt L, Du M, Wang J, Rollins J, Hanau R. Genetic analysis of cross fertility between two self-sterile strains ofGlomerella graminicola. Mycologia 2019. [DOI: 10.1080/00275514.2000.12061178] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Lisa Vaillancourt
- Department of Plant Pathology, S-305 Agricultural Science Building-North, University of Kentucky, Lexington, Kentucky 40506-0091
| | - Meizhu Du
- Department of Plant Pathology, S-305 Agricultural Science Building-North, University of Kentucky, Lexington, Kentucky 40506-0091
| | - Juan Wang
- Department of Botany and Plant Pathology, Lilly Hall, Purdue University, W. Lafayette, Indiana 47907-1155
| | - Jeffrey Rollins
- Department of Plant Pathology, University of Nebraska, P.O. Box 830722, Lincoln, Nebraska 68583-0722
| | - Robert Hanau
- Department of Botany and Plant Pathology, Lilly Hall, Purdue University, W. Lafayette, Indiana 47907-1155
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The mating system of the Eucalyptus canker pathogen Chrysoporthe austroafricana and closely related species. Fungal Genet Biol 2019; 123:41-52. [DOI: 10.1016/j.fgb.2018.12.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 11/29/2018] [Accepted: 12/03/2018] [Indexed: 11/18/2022]
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Liu F, Li G, Roux J, Barnes I, Wilson AM, Wingfield MJ, Chen S. Nine novel species of Huntiella from southern China with three distinct mating strategies and variable levels of pathogenicity. Mycologia 2018; 110:1145-1171. [DOI: 10.1080/00275514.2018.1515450] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- FeiFei Liu
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0028, South Africa
| | - GuoQing Li
- China Eucalypt Research Centre, Chinese Academy of Forestry, Zhanjiang 524022, Guangdong Province, China
| | - Jolanda Roux
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0028, South Africa
| | - Irene Barnes
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0028, South Africa
| | - Andrea M. Wilson
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0028, South Africa
| | - Michael J. Wingfield
- Department of Biochemistry, Genetics and Microbiology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria 0028, South Africa
| | - ShuaiFei Chen
- China Eucalypt Research Centre, Chinese Academy of Forestry, Zhanjiang 524022, Guangdong Province, China
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Wilson AM, van der Nest MA, Wilken PM, Wingfield MJ, Wingfield BD. Pheromone expression reveals putative mechanism of unisexuality in a saprobic ascomycete fungus. PLoS One 2018; 13:e0192517. [PMID: 29505565 PMCID: PMC5837088 DOI: 10.1371/journal.pone.0192517] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 01/24/2018] [Indexed: 01/11/2023] Open
Abstract
Homothallism (self-fertility) describes a wide variety of sexual strategies that enable a fungus to reproduce in the absence of a mating partner. Unisexual reproduction, a form of homothallism, is a process whereby a fungus can progress through sexual reproduction in the absence of mating genes previously considered essential for self-fertility. In this study, we consider the molecular mechanisms that allow for this unique sexual behaviour in the saprotrophic ascomycete; Huntiella moniliformis. These molecular mechanisms are also compared to the underlying mechanisms that control sex in Huntiella omanensis, a closely related, but self-sterile, species. The main finding was that H. omanensis displayed mating-type dependent expression of the a- and α-pheromones. This was in contrast to H. moniliformis where both pheromones were co-expressed during vegetative growth and sexual development. Furthermore, H. moniliformis also expressed the receptors of both pheromones. Consequently, this fungus is likely able to recognize and respond to the endogenously produced pheromones, allowing for self-fertility in the absence of other key mating genes. Overall, these results are concomitant with those reported for other unisexual species, but represent the first detailed study considering the unisexual behaviour of a filamentous fungus.
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Affiliation(s)
- Andi M. Wilson
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
- * E-mail:
| | - Magriet A. van der Nest
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
| | - P. Markus Wilken
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
| | - Michael J. Wingfield
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
| | - Brenda D. Wingfield
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Pretoria, South Africa
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Rodenburg SYA, Terhem RB, Veloso J, Stassen JHM, van Kan JAL. Functional Analysis of Mating Type Genes and Transcriptome Analysis during Fruiting Body Development of Botrytis cinerea. mBio 2018; 9:e01939-17. [PMID: 29440571 PMCID: PMC5821092 DOI: 10.1128/mbio.01939-17] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 01/17/2018] [Indexed: 02/07/2023] Open
Abstract
Botrytis cinerea is a plant-pathogenic fungus producing apothecia as sexual fruiting bodies. To study the function of mating type (MAT) genes, single-gene deletion mutants were generated in both genes of the MAT1-1 locus and both genes of the MAT1-2 locus. Deletion mutants in two MAT genes were entirely sterile, while mutants in the other two MAT genes were able to develop stipes but never formed an apothecial disk. Little was known about the reprogramming of gene expression during apothecium development. We analyzed transcriptomes of sclerotia, three stages of apothecium development (primordia, stipes, and apothecial disks), and ascospores by RNA sequencing. Ten secondary metabolite gene clusters were upregulated at the onset of sexual development and downregulated in ascospores released from apothecia. Notably, more than 3,900 genes were differentially expressed in ascospores compared to mature apothecial disks. Among the genes that were upregulated in ascospores were numerous genes encoding virulence factors, which reveals that ascospores are transcriptionally primed for infection prior to their arrival on a host plant. Strikingly, the massive transcriptional changes at the initiation and completion of the sexual cycle often affected clusters of genes, rather than randomly dispersed genes. Thirty-five clusters of genes were jointly upregulated during the onset of sexual reproduction, while 99 clusters of genes (comprising >900 genes) were jointly downregulated in ascospores. These transcriptional changes coincided with changes in expression of genes encoding enzymes participating in chromatin organization, hinting at the occurrence of massive epigenetic regulation of gene expression during sexual reproduction.IMPORTANCE Fungal fruiting bodies are formed by sexual reproduction. We studied the development of fruiting bodies ("apothecia") of the ubiquitous plant-pathogenic ascomycete Botrytis cinerea The role of mating type genes in apothecium development was investigated by targeted mutation. Two genes are essential for the initiation of sexual development; mutants in these genes are sterile. Two other genes were not essential for development of stipes; however, they were essential for stipes to develop a disk and produce sexual ascospores. We examined gene expression profiles during apothecium development, as well as in ascospores sampled from apothecia. We provide the first study ever of the transcriptome of pure ascospores in a filamentous fungus. The expression of numerous genes involved in plant infection was induced in the ascospores, implying that ascospores are developmentally primed for infection before their release from apothecia.
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Affiliation(s)
- Sander Y A Rodenburg
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
- Wageningen University, Bioinformatics Group, Wageningen, The Netherlands
| | - Razak B Terhem
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
| | - Javier Veloso
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
- Department of Plant Physiology, Faculty of Sciences, University of A Coruña, A Coruña, Spain
| | - Joost H M Stassen
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
| | - Jan A L van Kan
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
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Abstract
This article provides an overview of sexual reproduction in the ascomycetes, a phylum of fungi that is named after the specialized sacs or "asci" that hold the sexual spores. They have therefore also been referred to as the Sac Fungi due to these characteristic structures that typically contain four to eight ascospores. Ascomycetes are morphologically diverse and include single-celled yeasts, filamentous fungi, and more complex cup fungi. The sexual cycles of many species, including those of the model yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe and the filamentous saprobes Neurospora crassa, Aspergillus nidulans, and Podospora anserina, have been examined in depth. In addition, sexual or parasexual cycles have been uncovered in important human pathogens such as Candida albicans and Aspergillus fumigatus, as well as in plant pathogens such as Fusarium graminearum and Cochliobolus heterostrophus. We summarize what is known about sexual fecundity in ascomycetes, examine how structural changes at the mating-type locus dictate sexual behavior, and discuss recent studies that reveal that pheromone signaling pathways can be repurposed to serve cellular roles unrelated to sex.
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Mating-type genes of the anamorphic fungus Ulocladium botrytis affect both asexual sporulation and sexual reproduction. Sci Rep 2017; 7:7932. [PMID: 28801599 PMCID: PMC5554195 DOI: 10.1038/s41598-017-08471-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 07/13/2017] [Indexed: 11/23/2022] Open
Abstract
Ulocladium was thought to be a strictly asexual genus of filamentous fungi. However, Ulocladium strains were shown to possess both MAT1-1-1 and MAT1-2-1 genes as observed in homothallic filamentous Ascomycetes. Here, we demonstrate that the U. botrytis MAT genes play essential roles for controlling asexual traits (conidial size and number). Using reciprocal genetic transformation, we demonstrate that MAT genes from the related heterothallic species Cochliobolus heterostrophus can also influence U. botrytis colony growth, conidial number and size, and have a strong effect on the range of the number of septa/conidium. Moreover, U. botrytis MAT genes can also affect similar aspects of asexual reproduction when expressed in C. heterostrophus. Heterologous complementation using C. heterostrophus MAT genes shows that they have lost the ability to regulate sexual reproduction in U. botrytis, under the conditions we employed, while the reciprocal heterologous complementation demonstrates that U. botrytis MAT genes have the ability to partially induce sexual reproduction in C. heterostrophus. Thus, the genetic backgrounds of C. heterostrophus and U. botrytis play significant roles in determining the function of MAT genes on sexual reproduction in these two fungi species. These data further support the role of MAT genes in controlling asexual growth in filamentous Ascomycetes but also confirm that heterothallic and homothallic Dothideomycete fungi can be interconverted by the exchange of MAT genes.
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Affiliation(s)
- Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710
| | - Timothy Y. James
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109
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Aylward J, Steenkamp ET, Dreyer LL, Roets F, Wingfield MJ, Wingfield BD. Genetic basis for high population diversity in Protea-associated Knoxdaviesia. Fungal Genet Biol 2016; 96:47-57. [DOI: 10.1016/j.fgb.2016.10.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 09/12/2016] [Accepted: 10/04/2016] [Indexed: 11/25/2022]
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15
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Vegetative incompatibility in fungi: From recognition to cell death, whatever does the trick. FUNGAL BIOL REV 2016. [DOI: 10.1016/j.fbr.2016.08.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Metin B, Heitman J. Sexual Reproduction in Dermatophytes. Mycopathologia 2016; 182:45-55. [PMID: 27696123 DOI: 10.1007/s11046-016-0072-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Accepted: 09/25/2016] [Indexed: 01/12/2023]
Abstract
Sexual reproduction is a rich source of genetic variation and commonly observed among fungi. Basically two different modes of sexual reproduction are observed in fungi, namely heterothallism where two compatible mating types are required to undergo mating and homothallism in which the organism is self-fertile. The genomic region governing the process of sexual reproduction and sex determination is called the mating type (MAT) locus. In filamentous ascomycetes including dermatophytes, the MAT locus harbors two different transcription factor genes in two different mating types. This review focuses on sexual reproduction and the structure of the MAT locus in dermatophytes. The reproductive modes and the observed mating types are summarized for different phylogenetic clades of dermatophytes. In addition, the question of whether or not unisexual reproduction, an interesting form of homothallism, may be the sexual reproduction mode especially in anthropophilic dermatophytes is raised.
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Affiliation(s)
- Banu Metin
- Department of Food Engineering, Faculty of Engineering and Natural Sciences, Istanbul Sabahattin Zaim University, Halkali cad, No: 2, Halkali, 34303, Kucukcekmece, Istanbul, Turkey.
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, 27710, USA
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Heitman J. Evolution of sexual reproduction: a view from the Fungal Kingdom supports an evolutionary epoch with sex before sexes. FUNGAL BIOL REV 2015; 29:108-117. [PMID: 26834823 DOI: 10.1016/j.fbr.2015.08.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Sexual reproduction is conserved throughout each supergroup within the eukaryotic tree of life, and therefore thought to have evolved once and to have been present in the last eukaryotic common ancestor (LECA). Given the antiquity of sex, there are features of sexual reproduction that are ancient and ancestral, and thus shared in diverse extant organisms. On the other hand, the vast evolutionary distance that separates any given extant species from the LECA necessarily implies that other features of sex will be derived. While most types of sex we are familiar with involve two opposite sexes or mating types, recent studies in the fungal kingdom have revealed novel and unusual patterns of sexual reproduction, including unisexual reproduction. In this mode of reproduction a single mating type can on its own undergo self-fertile/homothallic reproduction, either with itself or with other members of the population of the same mating type. Unisexual reproduction has arisen independently as a derived feature in several different lineages. That a myriad of different types of sex determination and sex determinants abound in animals, plants, protists, and fungi suggests that sex specification itself may not be ancestral and instead may be a derived trait. If so, then the original form of sexual reproduction may have been unisexual, onto which sexes were superimposed as a later feature. In this model, unisexual reproduction is both an ancestral and a derived trait. In this review, we consider what is new and what is old about sexual reproduction from the unique vantage point of the fungal kingdom.
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Affiliation(s)
- Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710 USA
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Idnurm A, Hood ME, Johannesson H, Giraud T. Contrasted patterns in mating-type chromosomes in fungi: hotspots versus coldspots of recombination. FUNGAL BIOL REV 2015; 29:220-229. [PMID: 26688691 PMCID: PMC4680991 DOI: 10.1016/j.fbr.2015.06.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
It is striking that, while central to sexual reproduction, the genomic regions determining sex or mating-types are often characterized by suppressed recombination that leads to a decrease in the efficiency of selection, shelters genetic load, and inevitably contributes to their genic degeneration. Research on model and lesser-explored fungi has revealed similarities in recombination suppression of the genomic regions involved in mating compatibility across eukaryotes, but fungi also provide opposite examples of enhanced recombination in the genomic regions that determine their mating types. These contrasted patterns of genetic recombination (sensu lato, including gene conversion and ectopic recombination) in regions of the genome involved in mating compatibility point to important yet complex processes occurring in their evolution. A number of pieces in this puzzle remain to be solved, in particular on the unclear selective forces that may cause the patterns of recombination, prompting theoretical developments and experimental studies. This review thus points to fungi as a fascinating group for studying the various evolutionary forces at play in the genomic regions involved in mating compatibility.
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Affiliation(s)
- Alexander Idnurm
- School of BioSciences, University of Melbourne, VIC 3010, Australia
| | - Michael E. Hood
- Department of Biology, Amherst College, Amherst, Massachusetts 01002 USA
| | - Hanna Johannesson
- Department of Evolutionary Biology, Uppsala University, Norbyvägen 18D, 752 36 Uppsala, Sweden
| | - Tatiana Giraud
- Laboratoire Ecologie, Systématique et Evolution, UMR 8079 CNRS-UPS-AgroParisTech, Bâtiment 360, Université Paris-Sud, 91405 Orsay cedex, France
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Wilson AM, Wilken PM, van der Nest MA, Steenkamp ET, Wingfield MJ, Wingfield BD. Homothallism: an umbrella term for describing diverse sexual behaviours. IMA Fungus 2015. [PMID: 26203424 PMCID: PMC4500084 DOI: 10.5598/imafungus.2015.06.01.13] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Sexual reproduction is notoriously complex in fungi with species able to produce sexual progeny by utilizing a variety of different mechanisms. This is even more so for species employing multiple sexual strategies, which is a surprisingly common occurrence. While heterothallism is relatively well understood in terms of its physiological and molecular underpinnings, homothallism remains greatly understudied. This can be attributed to it involving numerous genetically distinct mechanisms that all result in self-fertility; including primary homothallism, pseudohomothallism, mating type switching, and unisexual reproduction. This review highlights the need to classify these homothallic mechanisms based on their molecular determinants and illustrates what is currently known about the multifaceted behaviours associated with homothallism.
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Affiliation(s)
- Andrea M Wilson
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Private Bag X20, Hatfield, Pretoria, South Africa, 0028
| | - P Markus Wilken
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Private Bag X20, Hatfield, Pretoria, South Africa, 0028
| | - Magriet A van der Nest
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Private Bag X20, Hatfield, Pretoria, South Africa, 0028
| | - Emma T Steenkamp
- Department of Microbiology and Plant Pathology, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa
| | - Michael J Wingfield
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Private Bag X20, Hatfield, Pretoria, South Africa, 0028
| | - Brenda D Wingfield
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Private Bag X20, Hatfield, Pretoria, South Africa, 0028
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Pondering Mating: Pneumocystis jirovecii, the Human Lung Pathogen, Selfs without Mating Type Switching, in Contrast to Its Close Relative Schizosaccharomyces pombe. mBio 2015; 6:e00583-15. [PMID: 25944864 PMCID: PMC4436060 DOI: 10.1128/mbio.00583-15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Vaghefi N, Ades PK, Hay FS, Pethybridge SJ, Ford R, Taylor PW. Identification of the MAT1 locus in Stagonosporopsis tanaceti, and exploring its potential for sexual reproduction in Australian pyrethrum fields. Fungal Biol 2015; 119:408-19. [DOI: 10.1016/j.funbio.2014.04.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 04/01/2014] [Indexed: 11/26/2022]
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22
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Fu C, Sun S, Billmyre RB, Roach KC, Heitman J. Unisexual versus bisexual mating in Cryptococcus neoformans: Consequences and biological impacts. Fungal Genet Biol 2015; 78:65-75. [PMID: 25173822 PMCID: PMC4344436 DOI: 10.1016/j.fgb.2014.08.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 08/14/2014] [Indexed: 11/22/2022]
Abstract
Cryptococcus neoformans is an opportunistic human fungal pathogen and can undergo both bisexual and unisexual mating. Despite the fact that one mating type is dispensable for unisexual mating, the two sexual cycles share surprisingly similar features. Both mating cycles are affected by similar environmental factors and regulated by the same pheromone response pathway. Recombination takes place during unisexual reproduction in a fashion similar to bisexual reproduction and can both admix pre-existing genetic diversity and also generate diversity de novo just like bisexual reproduction. These common features may allow the unisexual life cycle to provide phenotypic and genotypic plasticity for the natural Cryptococcus population, which is predominantly α mating type, and to avoid Muller's ratchet. The morphological transition from yeast to hyphal growth during both bisexual and unisexual mating may provide increased opportunities for outcrossing and the ability to forage for nutrients at a distance. The unisexual life cycle is a key evolutionary factor for Cryptococcus as a highly successful global fungal pathogen.
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Affiliation(s)
- Ci Fu
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Sheng Sun
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - R B Billmyre
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Kevin C Roach
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.
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Wilson AM, Godlonton T, van der Nest MA, Wilken PM, Wingfield MJ, Wingfield BD. Unisexual reproduction in Huntiella moniliformis. Fungal Genet Biol 2015; 80:1-9. [PMID: 25910452 DOI: 10.1016/j.fgb.2015.04.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 04/10/2015] [Accepted: 04/11/2015] [Indexed: 01/08/2023]
Abstract
Sexual reproduction in fungi is controlled by genes present at the mating type (MAT) locus, which typically harbors transcription factors that influence the expression of many sex-related genes. The MAT locus exists as two alternative idiomorphs in ascomycetous fungi and sexual reproduction is initiated when genes from both idiomorphs are expressed. Thus, the gene content of this locus determines whether a fungus is heterothallic (self-sterile) or homothallic (self-fertile). Recently, a unique sub-class of homothallism has been described in fungi, where individuals possessing a single MAT idiomorph can reproduce sexually in the absence of a partner. Using various mycological, molecular and bioinformatic techniques, we investigated the sexual strategies and characterized the MAT loci in two tree wound-infecting fungi, Huntiella moniliformis and Huntiella omanensis. H. omanensis was shown to exhibit a typically heterothallic sexual reproductive cycle, with isolates possessing either the MAT1-1 or MAT1-2 idiomorph. This was in contrast to the homothallism via unisexual reproduction that was shown in H. moniliformis, where only the MAT1-2-1 gene was present in sexually reproducing cultures. While the evolutionary benefit and mechanisms underpinning a unisexual mating strategy remain unknown, it could have evolved to minimize the costs, while retaining the benefits, of normal sexual reproduction.
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Affiliation(s)
- A M Wilson
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa
| | - T Godlonton
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa
| | - M A van der Nest
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa
| | - P M Wilken
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa
| | - M J Wingfield
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa
| | - B D Wingfield
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa.
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Yu JJ, Sun WX, Yu MN, Yin XL, Meng XK, Zhao J, Huang L, Huang L, Liu YF. Characterization of mating-type loci in rice false smut fungus Villosiclava virens. FEMS Microbiol Lett 2015; 362:fnv014. [DOI: 10.1093/femsle/fnv014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/29/2015] [Indexed: 11/12/2022] Open
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Affiliation(s)
- Marianna Feretzaki
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Joseph Heitman
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Medicine, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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26
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Duong TA, de Beer ZW, Wingfield BD, Wingfield MJ. Characterization of the mating-type genes in Leptographium procerum and Leptographium profanum. Fungal Biol 2013; 117:411-21. [PMID: 23809651 DOI: 10.1016/j.funbio.2013.04.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 04/11/2013] [Accepted: 04/12/2013] [Indexed: 11/20/2022]
Abstract
Leptographium procerum and the closely related species Leptographium profanum, are ascomycetes associated with root-infesting beetles on pines and hardwood trees, respectively. Both species occur in North America where they are apparently native. L. procerum has also been found in Europe, China New Zealand, and South Africa where it has most probably been introduced. As is true for many other Leptographium species, sexual states have never been observed in L. procerum or L. profanum. The objectives of this study were to clone and characterize the mating type loci of these fungi, and to develop markers to determine the mating types of individual isolates. To achieve this, a partial sequence of MAT1-2-1 was amplified using degenerate primers targeting the high mobility group (HMG) sequence. A complete MAT1-2 idiomorph of L. profanum was subsequently obtained by screening a genomic library using the HMG sequence as a probe. Long range PCR was used to amplify the complete MAT1-1 idiomorph of L. profanum and both the MAT1-1 and MAT1-2 idiomorphs of L. procerum. Characterization of the MAT idiomorphs suggests that the MAT genes are fully functional and that individuals of both these species are self-sterile in nature with a heterothallic mating system. Mating type markers were developed and tested on a population of L. procerum isolates from the USA, the assumed center of origin for this species. The results suggest that cryptic sexual reproduction is occurring or has recently taken place within this population.
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Affiliation(s)
- Tuan A Duong
- Department of Genetics, Forestry and Agricultural Biotechnology Institute-FABI, University of Pretoria, Pretoria 0002, South Africa.
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27
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Gioti A, Mushegian AA, Strandberg R, Stajich JE, Johannesson H. Unidirectional Evolutionary Transitions in Fungal Mating Systems and the Role of Transposable Elements. Mol Biol Evol 2012; 29:3215-26. [DOI: 10.1093/molbev/mss132] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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29
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Roles for receptors, pheromones, G proteins, and mating type genes during sexual reproduction in Neurospora crassa. Genetics 2012; 190:1389-404. [PMID: 22298702 DOI: 10.1534/genetics.111.136358] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Here we characterize the relationship between the PRE-2 pheromone receptor and its ligand, CCG-4, and the general requirements for receptors, pheromones, G proteins, and mating type genes during fusion of opposite mating-type cells and sexual sporulation in the multicellular fungus Neurospora crassa. PRE-2 is highly expressed in mat a cells and is localized in male and female reproductive structures. Δpre-2 mat a females do not respond chemotropically to mat A males (conidia) or form mature fruiting bodies (perithecia) or meiotic progeny (ascospores). Strains with swapped identity due to heterologous expression of pre-2 or ccg-4 behave normally in crosses with opposite mating-type strains. Coexpression of pre-2 and ccg-4 in the mat A background leads to self-attraction and development of barren perithecia without ascospores. Further perithecial development is achieved by inactivation of Sad-1, a gene required for meiotic gene silencing. Findings from studies involving forced heterokaryons of opposite mating-type strains show that presence of one receptor and its compatible pheromone is necessary and sufficient for perithecial development and ascospore production. Taken together, the results demonstrate that although receptors and pheromones control sexual identity, the mating-type genes (mat A and mat a) must be in two different nuclei to allow meiosis and sexual sporulation to occur.
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Complex mechanisms regulate developmental expression of the matA (HMG) mating type gene in homothallic Aspergillus nidulans. Genetics 2011; 189:795-808. [PMID: 21868608 DOI: 10.1534/genetics.111.131458] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Sexual reproduction is a fundamental developmental process that allows for genetic diversity through the control of zygote formation, recombination, and gametogenesis. The correct regulation of these events is paramount. Sexual reproduction in filamentous fungi, including mating strategy (self-fertilization/homothallism or outcrossing/heterothallism), is determined by the expression of mating type genes at mat loci. Aspergillus nidulans matA encodes a critical regulator that is a fungal ortholog of the hSRY/SOX9 HMG box proteins. In contrast to well-studied outcrossing systems, the molecular basis of homothallism and role of mating type genes during a self-fertile sexual cycle remain largely unknown. In this study the genetic model organism, A. nidulans, has been used to investigate the regulation and molecular functions of the matA mating type gene in a homothallic system. Our data demonstrate that complex regulatory mechanisms underlie functional matA expression during self-fertilization and sexual reproduction in A. nidulans. matA expression is suppressed in vegetative hyphae and is progressively derepressed during the sexual cycle. Elevated levels of matA transcript are required for differentiation of fruiting bodies, karyogamy, meiosis, and efficient formation of meiotic progeny. matA expression is driven from both initiator (Inr) and novel promoter elements that are tightly developmentally regulated by position-dependent and position-independent mechanisms. Deletion of an upstream silencing element, matA SE, results in derepressed expression from wild-type (wt) promoter elements and activation of an additional promoter. These studies provide novel insights into the molecular basis of homothallism in fungi and genetic regulation of sexual reproduction in eukaryotes.
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Nygren K, Strandberg R, Wallberg A, Nabholz B, Gustafsson T, García D, Cano J, Guarro J, Johannesson H. A comprehensive phylogeny of Neurospora reveals a link between reproductive mode and molecular evolution in fungi. Mol Phylogenet Evol 2011; 59:649-63. [DOI: 10.1016/j.ympev.2011.03.023] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 02/11/2011] [Accepted: 03/17/2011] [Indexed: 11/27/2022]
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Zhang S, Zhang YJ, Liu XZ, Wen HA, Wang M, Liu DS. Cloning and analysis of the MAT1-2-1 gene from the traditional Chinese medicinal fungus Ophiocordyceps sinensis. Fungal Biol 2011; 115:708-14. [PMID: 21802050 DOI: 10.1016/j.funbio.2011.05.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 05/09/2011] [Accepted: 05/18/2011] [Indexed: 10/18/2022]
Abstract
The entomopathogenic fungus Ophiocordyceps sinensis has been important in traditional Chinese medicine but has yet to be commercially cultivated. One bottleneck is the very low frequency of stromata formation from artificially infected moth larvae. The mating system of fungi is the determining factor for sexual reproduction, but mating-type genes of O. sinensis have not been previously investigated. In this study, the putative mating-type gene MAT1-2-1 within the MAT1-2 idiomorph was amplified by polymerase chain reaction (PCR) and was determined to consist of 859 nucleotides that encode 249 amino acids; genes within the MAT1-1 idiomorph, however, were not determined. The MAT1-2-1 gene contained the conserved high-mobility group (HMG) box, and MAT1-2-1 flanking sequences were subsequently obtained. Although no putative open reading frames of the MAT1-1 idiomorph were detected within the ca. 8-kb flanking sequences of MAT1-2-1, a putative DNA lyase gene (which is present next to both idiomorphs in some heterothallic fungi) was found ca. 3.0 kb downstream of MAT1-2-1. The intervening distance between MAT1-2-1 and the DNA lyase gene in O. sinensis is larger than that in Cordyceps militaris and Cordyceps takaomontana. In addition, O. sinensis showed low sequence similarities with C. militaris and C. takaomontana in both MAT1-2-1 and the DNA lyase gene. In the phylogenetic tree, different MAT1-2-1 haplotypes of O. sinensis clustered together with high bootstrap support. As a single-copy gene, MAT1-2-1 was detected in all examined O. sinensis isolates including tissue cultures and single-ascospore cultures. This report describes, for the first time, a mating-type gene of O. sinensis.
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Affiliation(s)
- Shu Zhang
- Institute of Applied Chemistry, Shanxi University, Taiyuan 030006, China
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Wendland J, Dünkler A, Walther A. Characterization of α-factor pheromone and pheromone receptor genes of Ashbya gossypii. FEMS Yeast Res 2011; 11:418-29. [DOI: 10.1111/j.1567-1364.2011.00732.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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Lu SW, Yun SH, Lee T, Turgeon BG. Altering sexual reproductive mode by interspecific exchange of MAT loci. Fungal Genet Biol 2011; 48:714-24. [PMID: 21514396 DOI: 10.1016/j.fgb.2011.04.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 02/27/2011] [Accepted: 04/08/2011] [Indexed: 12/23/2022]
Abstract
Sexual fungi can be self-sterile (heterothallic, requiring genetically distinct partners) or self-fertile (homothallic, no partner required). In most ascomycetes, a single mating type locus (MAT) controls the ability to reproduce sexually. In the genus Cochliobolus, all heterothallic species have either MAT1-1 or MAT1-2 (but never both) in different individuals whereas all homothallic species carry both MAT1-1 and MAT1-2 in the same nucleus of an individual. It has been demonstrated, previously, that a MAT gene from homothallic Cochliobolus luttrellii can confer self-mating ability on a mat-deleted strain of its heterothallic relative, Cochliobolus heterostrophus. In this reciprocal study, we expressed, separately, the heterothallic C. heterostrophus MAT1-1-1 and MAT1-2-1 genes in a mat-deleted homothallic C. luttrellii strain and asked if this converts homothallic C. luttrellii to heterothallism. We report that: (1) A C. luttrellii transgenic strain carrying C. heterostrophus MAT1-1-1 and a C. luttrellii transgenic strain carrying C. heterostrophus MAT1-2-1 can mate in a heterothallic manner and the fertility of the cross is similar to that of a wild type C. luttrellii self. Full tetrads are always found. (2) A C. luttrellii transgenic strain carrying C. heterostrophus MAT1-1-1 can mate with the parental wild type C. luttrellii MAT1-1;MAT1-2 strain, indicating the latter is able to outcross, a result which was expected but has not been demonstrated previously. (3) A C. luttrellii transgenic strain carrying C. heterostrophus MAT1-2-1 cannot mate with the parental wild type C. luttrellii MAT1-1;MAT1-2 strain, indicating outcrossing specificity. (4) Each transgenic C. luttrellii strain, carrying only a single C. heterostrophus MAT gene, is able to self, although all pseudothecia produced are smaller than those of wild type and fertility is low (about 4-15% of the number of wild type asci). These data support the argument that in Cochliobolus spp., the primary determinant of reproductive mode is MAT itself, and that a heterothallic strain can be made homothallic or a homothallic strain can be made heterothallic by exchange of MAT genes. The selfing ability of transgenic C. luttrellii strains also suggests that both MAT1-1-1 and MAT1-2-1 genes of C. heterostrophus carry equivalent transcription regulatory activities, each capable of promoting sexual development when alone, in a suitable genetic background.
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Affiliation(s)
- Shun-Wen Lu
- Department of Plant Pathology & Plant-Microbe Biology, Cornell University, Ithaca, NY 14853, USA
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Martin SH, Wingfield BD, Wingfield MJ, Steenkamp ET. Structure and evolution of the Fusarium mating type locus: new insights from the Gibberellafujikuroi complex. Fungal Genet Biol 2011; 48:731-40. [PMID: 21453780 DOI: 10.1016/j.fgb.2011.03.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2011] [Revised: 03/18/2011] [Accepted: 03/21/2011] [Indexed: 11/26/2022]
Abstract
Mating type genes are central to sexual reproduction and compatibility in Ascomycete fungi. However the "MAT" loci experience unique evolutionary pressures that can result in rapid divergence and enhanced inter-specific gene-flow (lateral gene transfer). In this study, molecular evolution of MAT loci was considered using the genus Fusarium (Teleomorph: Gibberella) as a model. Both MAT1-1 and MAT1-2 "idiomorphs" from eleven species of the Gibberellafujikuroi species complex were sequenced. Molecular evolution of the MAT loci from these heterothallic (self-sterile) species was compared with that of the MAT loci from nine homothallic (self-fertile) species in the Fusariumgraminearum species complex. Although Fusarium has previously been thought to have the same complement of four MAT genes that are found in Neurospora, we found evidence of a novel gene, MAT1-2-3, that may be specific to the Hypocreales. All MAT genes share a similar set of cis-regulatory motifs, although homothallic species might have recruited novel regulatory elements, which could potentially facilitate alternate expression of MAT1-1-1 and MAT1-2-1. FusariumMAT loci displayed evidence consistent with historical lateral gene-flow. Most notably, the MAT1-1 idiomorph of Fusariumsacchari appears to be unrelated to those of other species in the G.fujikuroi complex. In general, FusariumMAT genes are highly divergent. Both positive selection and relaxed selective constraint could account for this phenomenon. However, the extent of both recombination and inter-specific gene-flow in the MAT locus also appears to affect the rate of divergence.
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Affiliation(s)
- Simon H Martin
- Department of Genetics, Forestry and Agricultural Biotechnology Institute, University of Pretoria, South Africa
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36
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Mechanisms of unisexual mating in Cryptococcus neoformans. Fungal Genet Biol 2011; 48:651-60. [PMID: 21320625 DOI: 10.1016/j.fgb.2011.02.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2010] [Revised: 01/22/2011] [Accepted: 02/03/2011] [Indexed: 12/25/2022]
Abstract
Sex serves a pivotal role in genetic exchange and it contributes to the fitness and genetic diversity for eukaryotic populations. Although the importance of the canonical bisexual mating has been widely accepted, the significance of the evolution and maintenance of unisexual mating observed in some eukaryotes is unclear. The recent discovery of same-sex mating in the human fungal pathogen Cryptococcus neoformans and the revelation of its impact on the Cryptococcus global population structure provide a platform to elucidate the molecular mechanisms and significance of unisexual mating. Here, we review the evidence of unisexual mating in Cryptococcus and provide some perspective on the biological significance of this life style on the survival of this important fungal pathogen in the environment and in animal hosts. We also summarize our current understanding of the molecular mechanisms governing this unconventional mode of reproduction.
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Donaldson GC, Ball LA, Axelrood PE, Glass NL. Primer sets developed to amplify conserved genes from filamentous ascomycetes are useful in differentiating fusarium species associated with conifers. Appl Environ Microbiol 2010; 61:1331-40. [PMID: 16534991 PMCID: PMC1388409 DOI: 10.1128/aem.61.4.1331-1340.1995] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We examined the usefulness of primer sets designed to amplify introns within conserved genes in filamentous ascomycetes to differentiate 35 isolates representing six different species of Fusarium commonly found in association with conifer seedlings. We analyzed restriction fragment length polymorphisms (RFLP) in five amplified PCR products from each Fusarium isolate. The primers used in this study were constructed on the basis of sequence information from the H3, H4, and (beta)-tubulin genes in Neurospora crassa. Primers previously developed for the intergenic transcribed spacer region of the ribosomal DNA were also used. The degree of interspecific polymorphism observed in the PCR products from the six Fusarium species allowed differentiation by a limited number of amplifications and restriction endonuclease digestions. The level of intraspecific RFLP variation in the five PCR products was low in both Fusarium proliferatum and F. avenaceum but was high in a population sample of F. oxysporum isolates. Clustering of the 35 isolates by statistical analyses gave similar dendrograms for H3, H4, and (beta)-tubulin RFLP analysis, but a dendrogram produced by intergenic transcribed spacer analysis varied in the placement of some F. oxysporum isolates.
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Asexual cephalosporin C producer Acremonium chrysogenum carries a functional mating type locus. Appl Environ Microbiol 2008; 74:6006-16. [PMID: 18689517 DOI: 10.1128/aem.01188-08] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acremonium chrysogenum, the fungal producer of the pharmaceutically relevant beta-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 alpha-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 alpha-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 PaDeltaMAT 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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Wik L, Karlsson M, Johannesson H. The evolutionary trajectory of the mating-type (mat) genes in Neurospora relates to reproductive behavior of taxa. BMC Evol Biol 2008; 8:109. [PMID: 18405383 PMCID: PMC2335104 DOI: 10.1186/1471-2148-8-109] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2007] [Accepted: 04/11/2008] [Indexed: 12/23/2022] Open
Abstract
Background Comparative sequencing studies among a wide range of taxonomic groups, including fungi, have led to the discovery that reproductive genes evolve more rapidly than other genes. However, for fungal reproductive genes the question has remained whether the rapid evolution is a result of stochastic or deterministic processes. The mating-type (mat) genes constitute the master regulators of sexual reproduction in filamentous ascomycetes and here we present a study of the molecular evolution of the four mat-genes (mat a-1, mat A-1, mat A-2 and mat A-3) of 20 Neurospora taxa. Results We estimated nonsynonymous and synonymous substitution rates of genes to infer their evolutionary rate, and confirmed that the mat-genes evolve rapidly. Furthermore, the evolutionary trajectories are related to the reproductive modes of the taxa; likelihood methods revealed that positive selection acting on specific codons drives the diversity in heterothallic taxa, while among homothallic taxa the rapid evolution is due to a lack of selective constraint. The latter finding is supported by presence of stop codons and frame shift mutations disrupting the open reading frames of mat a-1, mat A-2 and mat A-3 in homothallic taxa. Lower selective constraints of mat-genes was found among homothallic than heterothallic taxa, and comparisons with non-reproductive genes argue that this disparity is not a nonspecific, genome-wide phenomenon. Conclusion Our data show that the mat-genes evolve rapidly in Neurospora. The rapid divergence is due to either adaptive evolution or lack of selective constraints, depending on the reproductive mode of the taxa. This is the first instance of positive selection acting on reproductive genes in the fungal kingdom, and illustrates how the evolutionary trajectory of reproductive genes can change after a switch in reproductive behaviour of an organism.
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Affiliation(s)
- Lotta Wik
- Uppsala University, Department of Evolutionary Biology, Norbyvägen 18D, SE-752 36 Uppsala, Sweden.
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40
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Covert SF, Aoki T, O'Donnell K, Starkey D, Holliday A, Geiser DM, Cheung F, Town C, Strom A, Juba J, Scandiani M, Yang XB. Sexual reproduction in the soybean sudden death syndrome pathogen Fusarium tucumaniae. Fungal Genet Biol 2007; 44:799-807. [PMID: 17300967 DOI: 10.1016/j.fgb.2006.12.009] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2006] [Revised: 12/07/2006] [Accepted: 12/22/2006] [Indexed: 11/16/2022]
Abstract
We investigated the sexual reproductive mode of the two most important etiological agents of soybean sudden death syndrome, Fusarium tucumaniae and Fusarium virguliforme. F. tucumaniae sexual crosses often were highly fertile, making it possible to assign mating type and assess female fertility in 24 South American isolates. These crosses produced red perithecia and oblong-elliptical ascospores, as is typical for sexual members of the F. solani species complex. Genotyping of progeny from three F. tucumaniae crosses confirmed that sexual recombination had occurred. In contrast, pairings among 17 U.S. F. virguliforme isolates never produced perithecia. Inter-species crosses between F. tucumaniae and F. virguliforme, in which infertile perithecia were induced only in one of the two F. tucumaniae mating types, suggest that all U.S. F. virguliforme isolates are of a single mating type. We conclude that the F. tucumaniae life cycle in S. America includes a sexual reproductive mode, and thus this species has greater potential for rapid evolution than the F. virguliforme population in the U.S., which may be exclusively asexual.
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Affiliation(s)
- S F Covert
- Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA.
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41
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Pöggeler S, Nowrousian M, Ringelberg C, Loros JJ, Dunlap JC, Kück U. Microarray and real-time PCR analyses reveal mating type-dependent gene expression in a homothallic fungus. Mol Genet Genomics 2006; 275:492-503. [PMID: 16482473 DOI: 10.1007/s00438-006-0107-y] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2005] [Accepted: 01/20/2006] [Indexed: 11/26/2022]
Abstract
Sordaria macrospora is a homothallic ascomycete which is able to form fertile fruiting bodies without a mating partner. To analyze the molecular basis of homothallism and the role of mating products during fruiting body development, we have deleted the mating type gene Smta-1 encoding a high-mobility group domain (HMG) protein. The DeltaSmta-1 deletion strain is morphologically wild type during vegetative growth, but it is unable to produce perithecia or ascospores. To identify genes expressed under control of Smta-1, we performed a cross-species microarray analysis using Neurospora crassa cDNA microarrays hybridized with S. macrospora targets. We identified 107 genes that are more than twofold up- or down-regulated in the mutant. Functional classification revealed that 81 genes have homologues with known or putative functions. Comparison of array data from DeltaSmta-1 with those from three phenotypically similar mutants revealed that only a limited set of ten genes is deregulated in all mutants. Remarkably, the ppg2 gene encoding a putative lipopeptide pheromone is 500-fold down-regulated in the DeltaSmta-1 mutant while in all other sterile mutants this gene is up-regulated.
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Affiliation(s)
- S Pöggeler
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, 44780, Bochum, Germany.
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42
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Kim H, Nelson MA. Molecular and functional analyses of poi-2, a novel gene highly expressed in sexual and perithecial tissues of Neurospora crassa. EUKARYOTIC CELL 2005; 4:900-10. [PMID: 15879524 PMCID: PMC1140099 DOI: 10.1128/ec.4.5.900-910.2005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The poi-2 gene is highly and specifically expressed in starved and sexual tissues of the filamentous fungus Neurospora crassa. It encodes a 27-kDa protein, as shown by in vitro transcription and translation. The POI2 protein contains a hydrophobic signal sequence at the amino terminus followed by novel 16 tandem repeats of 13 to 14 amino acid residues; all repeats are separated by Kex2 processing sites. Repeat-induced point mutation (RIP)-mediated gene disruption was used to generate poi-2 mutants, and the mutated sequences showed either one of two distinct patterns: typical RIPs (GC-to-AT transitions) or insertion-deletion (indel) mutations. Although the poi-2 strains contained numerous mutations, all retained intact open reading frames (ORFs) of various lengths. They showed greatly reduced vegetative growth and protoperithecial formation and low viability of their sexual progeny. All poi-2 mutants had similar defects in male fertility and the mating response, but the nature of female fertility defects varied and corresponded to the length of the residual poi-2 ORF. Mutants with ORFs of approximately normal length occasionally completed sexual development and produced viable ascospores, while a mutant with a severely truncated ORF was female sterile due to its inability to form protoperithecia. Thus, poi-2 is essential for differentiation of female reproductive structures and perithecial development as well as for normal vegetative growth. The POI2 protein is involved in the mating response, probably as a component in the pathway rather than as a pheromone.
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Affiliation(s)
- Hyojeong Kim
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
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43
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O'Donnell K, Ward TJ, Geiser DM, Corby Kistler H, Aoki T. Genealogical concordance between the mating type locus and seven other nuclear genes supports formal recognition of nine phylogenetically distinct species within the Fusarium graminearum clade. Fungal Genet Biol 2004; 41:600-23. [PMID: 15121083 DOI: 10.1016/j.fgb.2004.03.003] [Citation(s) in RCA: 423] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2003] [Accepted: 03/05/2004] [Indexed: 10/26/2022]
Abstract
Species limits were investigated within the Fusarium graminearum clade (Fg clade) through phylogenetic analyses of DNA sequences from portions of 11 nuclear genes including the mating-type (MAT) locus. Nine phylogenetically distinct species were resolved within the Fg clade, and they all possess contiguous MAT1-1 and MAT1-2 idiomorphs consistent with a homothallic reproductive mode. In contrast, only one of the two MAT idiomorphs was found in five other species, four of which were putatively asexual, and the other was heterothallic. Molecular evolutionary analyses indicate the MAT genes are under strong purifying selection and that they are functionally constrained, even in species for which a sexual state is unknown. The phylogeny supports a monophyletic and apomorphic origin of homothallism within this clade. Morphological analyses demonstrate that a combination of conidial characters could be used to differentiate three species and three species pairs. Species rank is formally proposed for the eight unnamed species within the Fg clade using fixed nucleotide characters.
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Affiliation(s)
- Kerry O'Donnell
- National Center for Agricultural Utilization Research, US Department of Agriculture, Agricultural Research Service, Peoria, IL 61604, USA.
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44
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Lee J, Lee T, Lee YW, Yun SH, Turgeon BG. Shifting fungal reproductive mode by manipulation of mating type genes: obligatory heterothallism of Gibberella zeae. Mol Microbiol 2003; 50:145-52. [PMID: 14507370 DOI: 10.1046/j.1365-2958.2003.03694.x] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Fungi capable of sexual reproduction use heterothallic (self-sterile) or homothallic (self-fertile) mating strategies. In most ascomycetes, a single mating type locus, MAT, with two alternative forms (MAT1-1 and MAT1-2) called idiomorphs, controls mating ability. In heterothallic ascomycetes, these alternative idiomorphs reside in different nuclei. In contrast, most homothallic ascomycetes carry both MAT1-1 and MAT1-2 in a single nucleus, usually closely linked. An example of the latter is Gibberella zeae, a species that is capable of both selfing and outcrossing. G. zeae is a devastating cereal pathogen of ubiquitous geographical distribution, and also a producer of mycotoxins that threaten human and animal health. We asked whether G. zeae could be made strictly heterothallic by manipulation of MAT. Targeted gene replacement was used to differentially delete MAT1-1 or MAT1-2 from a wild-type haploid MAT1-1; MAT1-2 strain, resulting in MAT1-1; mat1-2, mat1-1; MAT1-2 strains that were self-sterile, yet able to cross to wild-type testers and, more importantly, to each other. These results indicated that differential deletion of MAT idiomorphs eliminates selfing ability of G. zeae, but the ability to outcross is retained. They also indicated that both MAT idiomorphs are required for self-fertility. To our knowledge, this is the first report of complete conversion of fungal reproductive strategy from homothallic to heterothallic by targeted manipulation of MAT. Practically, this approach opens the door to simple and efficient procedures for obtaining sexual recombinants of G. zeae that will be useful for genetic analyses of pathogenicity and other traits, such as the ability to produce mycotoxins.
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Affiliation(s)
- Jungkwan Lee
- School of Agricultural Biotechnology, Seoul National University, Suwon 441-744, Korea.
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Ueng PP, Dai Q, Cui KR, Czembor PC, Cunfer BM, Tsang H, Arseniuk E, Bergstrom GC. Sequence diversity of mating-type genes in Phaeosphaeria avenaria. Curr Genet 2003; 43:121-30. [PMID: 12695852 DOI: 10.1007/s00294-003-0377-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2002] [Revised: 12/23/2002] [Accepted: 01/15/2003] [Indexed: 10/25/2022]
Abstract
Phaeosphaeria avenaria, one of the causal agents of stagonospora leaf blotch diseases in cereals, is composed of two subspecies, P. avenaria f. sp. triticea (Pat) and P. avenaria f. sp. avenaria (Paa). The Pat subspecies was grouped into Pat1-Pat3, based on restriction fragment length polymorphism (RFLP) and ribosomal DNA (rDNA) internal transcribed spacer (ITS) sequences in previous studies. Mating-type genes and their potential use in phylogeny and molecular classification were studied by DNA hybridization and PCR amplification. The majority of Pat1 isolates reported to be homothallic and producing sexual reproduction structures on cultural media had only the MAT1-1 gene. Minor sequence variations were found in the conserved region of MAT1-1 gene in Pat1 isolates. However, both mating-type genes, MAT1-1 and MAT1-2, were identified in P. avenaria isolates represented by ATCC12277 from oats (Paa) and the Pat2 isolates from foxtail barley ( Hordeum jubatum L.). Cluster analyses based on mating-type gene conserved regions revealed that cereal Phaeosphaeria is not phylogenetically closely related to other ascomycetes, including Mycosphaerella graminicola (anamorph Septoria tritici). The sequence diversity of mating-type genes in Pat and Paa supports our previous phylogenetic relationship and molecular classification based on RFLP fingerprinting and rDNA ITS sequences.
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Affiliation(s)
- Peter P Ueng
- Molecular Plant Pathology Laboratory, U.S. Department of Agriculture, ARS, Beltsville, MD 20705, USA.
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Kim H, Metzenberg RL, Nelson MA. Multiple functions of mfa-1, a putative pheromone precursor gene of Neurospora crassa. EUKARYOTIC CELL 2002; 1:987-99. [PMID: 12477799 PMCID: PMC138756 DOI: 10.1128/ec.1.6.987-999.2002] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A putative pheromone precursor gene of Neurospora crassa, mfa-1 (which encodes mating factor a-1), was identified as the most abundant clone in starved mycelial and perithecial cDNA libraries. Northern analysis demonstrated high mfa-1 expression in all mating type a tissues and suggested low expression levels in mat A tissues. The mfa-1 gene was expressed as an approximately 1.2-kb transcript predicted to encode a 24-residue peptide, followed by a long 3' untranslated region (3' UTR). The predicted MFA1 sequence showed 100% sequence identity to PPG2 of Sordaria macrospora and structural similarity (a carboxy-terminal CAAX motif) to many hydrophobic fungal pheromone precursors. Mutants with a disrupted open reading frame (ORF) in which the critical cysteine residue had been changed to a nonprenylatable residue, tyrosine (YAAX mutants), were isolated, as were mfa-1 mutants with intact ORFs but multiple mutations in the 3' noncoding region (CAAX mutants). The 3' UTR is required for the full range of mfa-1 gene activity. Both classes of mutants showed delayed and reduced vegetative growth (which was suppressed by supplementation with a minute amount [30 micro M] of ornithine, citrulline, or arginine), as well as aberrant sexual development. When crossed as female parents to wild-type males, the CAAX and YAAX mutants showed greatly reduced ascospore production. No ascospores were produced in homozygous mfa-1 crosses. As males, YAAX mat a mutants were unable to attract wild-type mat A trichogynes (female-specific hyphae) or to initiate sexual development, while CAAX mat a mutants were able to mate and produce sexual progeny despite their inability to attract mat A trichogynes. In the mat A background, both CAAX and YAAX mutants showed normal male fertility but defective vegetative growth and aberrant female sexual development. Thus, the mfa-1 gene appears to have multiple roles in N. crassa development: (i) it encodes a hydrophobic pheromone with a putative farnesylated and carboxymethylated C-terminal cysteine residue, required by mat a to attract trichogynes of mat A; (ii) it is involved in female sexual development and ascospore production in both mating types; and (iii) it functions in vegetative growth of both mating types.
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MESH Headings
- 3' Untranslated Regions
- Base Sequence
- Blotting, Southern
- Cell Division
- Chromosome Mapping
- Crosses, Genetic
- Cysteine/chemistry
- DNA, Complementary/metabolism
- Fungal Proteins/chemistry
- Fungal Proteins/metabolism
- Gene Library
- Genes, Fungal
- Genes, Mating Type, Fungal
- Genetic Complementation Test
- Methylation
- Molecular Sequence Data
- Mutation
- Neurospora crassa/genetics
- Neurospora crassa/physiology
- Nucleic Acid Conformation
- Open Reading Frames
- Pheromones/chemistry
- Pheromones/metabolism
- Plasmids/metabolism
- Point Mutation
- Polymorphism, Restriction Fragment Length
- Protein Prenylation
- Protein Structure, Tertiary
- Sequence Analysis, DNA
- Sequence Homology, Nucleic Acid
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Affiliation(s)
- Hyojeong Kim
- Department of Biology, The University of New Mexico, Albuquerque, New Mexico 87131, USA
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47
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Masloff S, Jacobsen S, Pöggeler S, Kück U. Functional analysis of the C6 zinc finger gene pro1 involved in fungal sexual development. Fungal Genet Biol 2002; 36:107-16. [PMID: 12081464 DOI: 10.1016/s1087-1845(02)00010-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The pro1 gene, controlling fruiting body development in the homothallic ascomycete Sordaria macrospora, encodes a C6 zinc finger protein with a typical DNA binding domain of GAL4-like C6 zinc finger proteins as well as a putative nuclear targeting signal. In the corresponding mutant pro1, the pro1 gene is deleted, and the transition of primordia into mature fruiting bodies is prevented. To further characterize the PRO1 polypeptide, the yeast system was used for identifying a transactivation domain in the N-terminal half of PRO1, which probably also functions in S. macrospora. The functional analysis was extended by using truncated versions of the pro1 gene in complementation transformations of a deltapro1 mutant. Interestingly, the 5' part of the pro1 gene encoding the DNA binding and transactivation domain as well as putative nuclear targeting signals was sufficient to restore fertility in the sterile pro1 mutant. In vitro mutagenesis verified that the DNA binding domain is essential for normal fruiting body development. This was concluded from transformation experiments with eight pro1 derivatives containing triplet substitutions in conserved codons of the DNA binding domain; some, but not all, failed in restoring the wild-type phenotype in mutant pro1. Using a PCR-based cloning strategy, pro1 homologs from the two related heterothallic species Neurospora crassa and Sordaria brevicollis were isolated, showing similarities in the predicted amino acid sequences of 91 and 90%, respectively. When a N. crassa pro1 cDNA clone was used in complementation transformations, we succeeded in restoring the wild-type phenotype to the S. macrospora pro1 mutant. These data suggest that pro1 homologs from heterothallic species can provide the pro1 function in homothallic ascomycetes. Based on the published sequence of the N. crassa genome, we identified hpro1A, another transcriptionally expressed gene, with a similarity of 40% to the pro1 genes, which is present as a single copy gene in N. crassa as well as in S. macrospora.
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Affiliation(s)
- Sandra Masloff
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, D-44780 Bochum, Germany
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48
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Yun SH, Arie T, Kaneko I, Yoder OC, Turgeon BG. Molecular organization of mating type loci in heterothallic, homothallic, and asexual Gibberella/Fusarium species. Fungal Genet Biol 2000; 31:7-20. [PMID: 11118131 DOI: 10.1006/fgbi.2000.1226] [Citation(s) in RCA: 202] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mating type (MAT) genes were cloned from three members of the Gibberella/Fusarium complex that differ in reproductive mode: heterothallic G. fujikuroi, homothallic G. zeae, and asexual F. oxysporum. The G. fujikuroi MAT locus organization is typical of other heterothallic pyrenomycetes characterized to date; i.e., there are three genes at MAT1-1 and one at MAT1-2. G. zeae has homologues of all four genes encoded by the two G. fujikuroi MAT idiomorphs, tightly linked on the same chromosome, interspersed with sequences unique to G. zeae. Field isolates of F. oxysporum, although asexual, have either the MAT1-1 or the MAT1-2 genes found in sexual species and these genes are highly similar to those of heterothallic G. fujikuroi. RT-PCR analysis proved that the F. oxysporum MAT genes are expressed and that all putative introns found in each of the four MAT genes in G. fujikuroi and F. oxysporum are removed. Apparent failure of F. oxysporum to reproduce sexually could not be attributed to mutations in the MAT genes themselves.
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Affiliation(s)
- S H Yun
- Department of Plant Pathology, Cornell University, 334 Plant Science Building, Ithaca, New York 14853, USA
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49
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Turgeon BG, Yoder OC. Proposed nomenclature for mating type genes of filamentous ascomycetes. Fungal Genet Biol 2000; 31:1-5. [PMID: 11118130 DOI: 10.1006/fgbi.2000.1227] [Citation(s) in RCA: 222] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- B G Turgeon
- Department of Plant Pathology, Cornell University, 334 Plant Science Building, Ithaca, New York 14853, USA.
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50
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Hiscock SJ, Kües U. Cellular and molecular mechanisms of sexual incompatibility in plants and fungi. INTERNATIONAL REVIEW OF CYTOLOGY 1999; 193:165-295. [PMID: 10494623 DOI: 10.1016/s0074-7696(08)61781-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Plants and fungi show an astonishing diversity of mechanisms to promote outbreeding, the most widespread of which is sexual incompatibility. Sexual incompatibility involves molecular recognition between mating partners. In fungi and algae, highly polymorphic mating-type loci mediate mating through complementary interactions between molecules encoded or regulated by different mating-type haplotypes, whereas in flowering plants polymorphic self-incompatibility loci regulate mate recognition through oppositional interactions between molecules encoded by the same self-incompatibility haplotypes. This subtle mechanistic difference is a consequence of the different life cycles of fungi, algae, and flowering plants. Recent molecular and biochemical studies have provided fascinating insights into the mechanisms of mate recognition and are beginning to shed light on evolution and population genetics of these extraordinarily polymorphic genetic systems of incompatibility.
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Affiliation(s)
- S J Hiscock
- Department of Plant Sciences, University of Oxford, United Kingdom
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