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Tatiana Giraud - One of the best experts on this subject based on the ideXlab platform.
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Identification of the First Oomycete Mating-Type Locus Sequence in the Grapevine Downy Mildew Pathogen, Plasmopara viticola
Current Biology - CB, 2020Co-Authors: Yann Dussert, Ludovic Legrand, Isabelle Mazet, Carole Couture, Marie-christine Piron, Rémy-félix Serre, Olivier Bouchez, Pere Mestre, Silvia Toffolatti, Tatiana GiraudAbstract:Mating Types are self-incompatibility systems that promote outcrossing in plants, fungi, and oomycetes. Mating-Type genes have been widely studied in plants and fungi but have yet to be identified in oomycetes, eukaryotic organisms closely related to brown algae that cause many destructive animal and plant diseases. We identified the Mating-Type locus of Plasmopara viticola, the oomycete responsible for grapevine downy mildew, one of the most damaging grapevine diseases worldwide. Using a genome-wide association approach, we identified a 570-kb repeat-rich non-recombining region controlling Mating Types, with two highly divergent alleles. We showed that one Mating Type was homozygous, whereas the other was heterozygous at this locus. The Mating-Type locus encompassed 40 genes, including one encoding a putative hormone receptor. Functional studies will, however, be required to validate the function of these genes and find the actual determinants of Mating Type. Our findings have fundamental implications for our understanding of the evolution of Mating Types, as they reveal a unique determinism involving an asymmetry of heterozygosity, as in sex chromosomes and unlike other Mating-Type systems. This identification of the Mating-Type locus in such an economically important crop pathogen also has applied implications, as outcrossing facilitates rapid evolution and resistance to harsh environmental conditions.
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extensive divergence between Mating Type chromosomes of the anther smut fungus
Genetics, 2013Co-Authors: Michael E Hood, Elsa Petit, Tatiana GiraudAbstract:Genomic regions that determine Mating compatibility are subject to distinct evolutionary forces that can lead to a cessation of meiotic recombination and the accumulation of structural changes between members of the homologous chromosome pair. The relatively recent discovery of dimorphic Mating-Type chromosomes in fungi can aid the understanding of sex chromosome evolution that is common to dioecious plants and animals. For the anther-smut fungus, Microbotryum lychnidis-dioicae (= M. violaceum isolated from Silene latifolia), the extent of recombination cessation on the dimorphic Mating-Type chromosomes has been conflictingly reported. Comparison of restriction digest optical maps for the two Mating-Type chromosomes shows that divergence extends over 90% of the chromosome lengths, flanked at either end by two pseudoautosomal regions. Evidence to support the expansion of recombination cessation in stages from the Mating-Type locus toward the pseudoautosomal regions was not found, but evidence of such expansion could be obscured by ongoing processes that affect genome structure. This study encourages the comparison of forces that may drive large-scale recombination suppression in fungi and other eukaryotes characterized by dimorphic chromosome pairs associated with sexual life cycles.
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extensive divergence between Mating Type chromosomes of the anther smut fungus
Genetics, 2013Co-Authors: Michael E Hood, Elsa Petit, Tatiana GiraudAbstract:Genomic regions that determine Mating compatibility are subject to distinct evolutionary forces that can lead to a cessation of meiotic recombination and the accumulation of structural changes between members of the homologous chromosome pair. The relatively recent discovery of dimorphic Mating-Type chromosomes in fungi can aid the understanding of sex chromosome evolution that is common to dioecious plants and animals. For the anther-smut fungus, Microbotryum lychnidis-dioicae (= M. violaceum isolated from Silene latifolia), the extent of recombination cessation on the dimorphic Mating-Type chromosomes has been conflictingly reported. Comparison of restriction digest optical maps for the two Mating-Type chromosomes shows that divergence extends over 90% of the chromosome lengths, flanked at either end by two pseudoautosomal regions. Evidence to support the expansion of recombination cessation in stages from the Mating-Type locus toward the pseudoautosomal regions was not found, but evidence of such expansion could be obscured by ongoing processes that affect genome structure. This study encourages the comparison of forces that may drive large-scale recombination suppression in fungi and other eukaryotes characterized by dimorphic chromosome pairs associated with sexual life cycles.
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Linkage to the Mating-Type locus across the genus microbotryum: insights into nonrecombining chromosomes
Evolution, 2012Co-Authors: Elsa Petit, Damien De Vienne, Gabriela Aguileta, Tatiana Giraud, Marco A Coelho, Joelle Amselem, Jonathan Kreplak, Julie Poulain, Frédérick Gavory, Patrick WinckerAbstract:Parallels have been drawn between the evolution of nonrecombining regions in fungal Mating-Type chromosomes and animal and plant sex chromosomes, particularly regarding the stages of recombination cessation forming evolutionary strata of allelic divergence. Currently, evidence and explanations for recombination cessation in fungi are sparse, and the presence of evolutionary strata has been examined in a minimal number of fungal taxa. Here, the basidiomycete genus Microbotryum was used to determine the history of recombination cessation for loci on the Mating-Type chromosomes. Ancestry of linkage with Mating Type for 13 loci was assessed across 20 species by a phylogenetic method. No locus was found to exhibit trans-specific polymorphism for alternate alleles as old as the Mating pheromone receptor, indicating that ages of linkage to Mating Type varied among the loci. The ordering of loci in the ancestry of linkage to Mating Type does not agree with their previously proposed assignments to evolutionary strata. This study suggests that processes capable of influencing divergence between alternate alleles may act at loci in the nonrecombining regions (e.g., gene conversion) and encourages further work to dissect the evolutionary processes acting upon genomic regions that determine Mating compatibility.
Kenneth H. Wolfe - One of the best experts on this subject based on the ideXlab platform.
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Multiple Reinventions of Mating-Type Switching During Budding Yeast Evolution
Current Biology, 2019Co-Authors: Tadeusz Krassowski, Jacek Kominek, Xing-xing Shen, Dana A. Opulente, Xiaofan Zhou, Antonis Rokas, Chris Todd Hittinger, Kenneth H. WolfeAbstract:Summary Cell Type in budding yeasts is determined by the genoType at the Mating-Type (MAT) locus, but yeast species differ widely in their Mating compatibility systems and life cycles. Among sexual yeasts, heterothallic species are those in which haploid strains fall into two distinct and stable Mating Types (MATa and MATα), whereas homothallic species are those that can switch Mating Types or that appear not to have distinct Mating Types [ 1 , 2 ]. The evolutionary history of these Mating compatibility systems is uncertain, particularly regarding the number and direction of transitions between homothallism and heterothallism, and regarding whether the process of Mating-Type switching had a single origin [ 3 , 4 , 5 ]. Here, we inferred the Mating compatibility systems of 332 budding yeast species from their genome sequences. By reference to a robust phylogenomic tree [ 6 ], we detected evolutionary transitions between heterothallism and homothallism, and among different forms of homothallism. We find that Mating-Type switching has arisen independently at least 11 times during yeast evolution and that transitions from heterothallism to homothallism greatly outnumber transitions in the opposite direction (31 versus 3). Although the 3-locus MAT-HML-HMR mechanism of Mating-Type switching as seen in Saccharomyces cerevisiae had a single evolutionary origin in budding yeasts, simpler “flip/flop” mechanisms of switching evolved separately in at least 10 other groups of yeasts. These results point to the adaptive value of homothallism and Mating-Type switching to unicellular fungi.
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An Evolutionary Perspective on Yeast Mating-Type Switching.
Genetics, 2017Co-Authors: Sara J. Hanson, Kenneth H. WolfeAbstract:Cell differentiation in yeast species is controlled by a reversible, programmed DNA-rearrangement process called Mating-Type switching. Switching is achieved by two functionally similar but structurally distinct processes in the budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe In both species, haploid cells possess one active and two silent copies of the Mating-Type locus (a three-cassette structure), the active locus is cleaved, and synthesis-dependent strand annealing is used to replace it with a copy of a silent locus encoding the opposite Mating-Type information. Each species has its own set of components responsible for regulating these processes. In this review, we summarize knowledge about the function and evolution of Mating-Type switching components in these species, including mechanisms of heterochromatin formation, MAT locus cleavage, donor bias, lineage tracking, and environmental regulation of switching. We compare switching in these well-studied species to others such as Kluyveromyces lactis and the methylotrophic yeasts Ogataea polymorpha and Komagataella phaffii We focus on some key questions: Which cells switch Mating Type? What molecular apparatus is required for switching? Where did it come from? And what is the evolutionary purpose of switching?
Elsa Petit - One of the best experts on this subject based on the ideXlab platform.
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degeneration of the nonrecombining regions in the Mating Type chromosomes of the anther smut fungi
Molecular Biology and Evolution, 2015Co-Authors: Hélène Badouin, Michael E Hood, Elsa Petit, Eric Fontanillas, Valerie Barbe, Jerome GouzyAbstract:Dimorphic Mating-Type chromosomes in fungi are excellent models for understanding the genomic consequences of recombination suppression. Their suppressed recombination and reduced effective population size are expected to limit the efficacy of natural selection, leading to genomic degeneration. Our aim was to identify the sequences of the MatingType chromosomes (a1and a2) of the anther-smut fungi and to investigate degeneration in their nonrecombining regions. We used the haploid a1 Microbotryum lychnidis-dioicae reference genome sequence. The a1 and a2 Mating-Type chromosomes were both isolated electrophoretically and sequenced. Integration with restriction-digest optical maps identified regions of recombination and nonrecombination in the Mating-Type chromosomes. Genome sequence data were also obtained for 12 other Microbotryum species. We found strong evidence of degeneration across the genus in the nonrecombining regions of the Mating-Type chromosomes, with significantly higher rates of nonsynonymous substitution (dN/dS) than in nonMating-Type chromosomes or in recombining regions of the Mating-Type chromosomes. The nonrecombining regions of the Mating-Type chromosomes also showed high transposable element content, weak gene expression, and gene losses. The levels of degeneration did not differ between the a1 and a2 Mating-Type chromosomes, consistent with the lack of homogametic/heterogametic asymmetry between them, and contrasting with X/Y or Z/W sex chromosomes.
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extensive divergence between Mating Type chromosomes of the anther smut fungus
Genetics, 2013Co-Authors: Michael E Hood, Elsa Petit, Tatiana GiraudAbstract:Genomic regions that determine Mating compatibility are subject to distinct evolutionary forces that can lead to a cessation of meiotic recombination and the accumulation of structural changes between members of the homologous chromosome pair. The relatively recent discovery of dimorphic Mating-Type chromosomes in fungi can aid the understanding of sex chromosome evolution that is common to dioecious plants and animals. For the anther-smut fungus, Microbotryum lychnidis-dioicae (= M. violaceum isolated from Silene latifolia), the extent of recombination cessation on the dimorphic Mating-Type chromosomes has been conflictingly reported. Comparison of restriction digest optical maps for the two Mating-Type chromosomes shows that divergence extends over 90% of the chromosome lengths, flanked at either end by two pseudoautosomal regions. Evidence to support the expansion of recombination cessation in stages from the Mating-Type locus toward the pseudoautosomal regions was not found, but evidence of such expansion could be obscured by ongoing processes that affect genome structure. This study encourages the comparison of forces that may drive large-scale recombination suppression in fungi and other eukaryotes characterized by dimorphic chromosome pairs associated with sexual life cycles.
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extensive divergence between Mating Type chromosomes of the anther smut fungus
Genetics, 2013Co-Authors: Michael E Hood, Elsa Petit, Tatiana GiraudAbstract:Genomic regions that determine Mating compatibility are subject to distinct evolutionary forces that can lead to a cessation of meiotic recombination and the accumulation of structural changes between members of the homologous chromosome pair. The relatively recent discovery of dimorphic Mating-Type chromosomes in fungi can aid the understanding of sex chromosome evolution that is common to dioecious plants and animals. For the anther-smut fungus, Microbotryum lychnidis-dioicae (= M. violaceum isolated from Silene latifolia), the extent of recombination cessation on the dimorphic Mating-Type chromosomes has been conflictingly reported. Comparison of restriction digest optical maps for the two Mating-Type chromosomes shows that divergence extends over 90% of the chromosome lengths, flanked at either end by two pseudoautosomal regions. Evidence to support the expansion of recombination cessation in stages from the Mating-Type locus toward the pseudoautosomal regions was not found, but evidence of such expansion could be obscured by ongoing processes that affect genome structure. This study encourages the comparison of forces that may drive large-scale recombination suppression in fungi and other eukaryotes characterized by dimorphic chromosome pairs associated with sexual life cycles.
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Linkage to the Mating-Type locus across the genus microbotryum: insights into nonrecombining chromosomes
Evolution, 2012Co-Authors: Elsa Petit, Damien De Vienne, Gabriela Aguileta, Tatiana Giraud, Marco A Coelho, Joelle Amselem, Jonathan Kreplak, Julie Poulain, Frédérick Gavory, Patrick WinckerAbstract:Parallels have been drawn between the evolution of nonrecombining regions in fungal Mating-Type chromosomes and animal and plant sex chromosomes, particularly regarding the stages of recombination cessation forming evolutionary strata of allelic divergence. Currently, evidence and explanations for recombination cessation in fungi are sparse, and the presence of evolutionary strata has been examined in a minimal number of fungal taxa. Here, the basidiomycete genus Microbotryum was used to determine the history of recombination cessation for loci on the Mating-Type chromosomes. Ancestry of linkage with Mating Type for 13 loci was assessed across 20 species by a phylogenetic method. No locus was found to exhibit trans-specific polymorphism for alternate alleles as old as the Mating pheromone receptor, indicating that ages of linkage to Mating Type varied among the loci. The ordering of loci in the ancestry of linkage to Mating Type does not agree with their previously proposed assignments to evolutionary strata. This study suggests that processes capable of influencing divergence between alternate alleles may act at loci in the nonrecombining regions (e.g., gene conversion) and encourages further work to dissect the evolutionary processes acting upon genomic regions that determine Mating compatibility.
James E. Haber - One of the best experts on this subject based on the ideXlab platform.
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Mating Type genes and mat switching in saccharomyces cerevisiae
Genetics, 2012Co-Authors: James E. HaberAbstract:Mating Type in Saccharomyces cerevisiae is determined by two nonhomologous alleles, MATa and MATα. These sequences encode regulators of the two different haploid Mating Types and of the diploids formed by their conjugation. Analysis of the MATa1, MATα1, and MATα2 alleles provided one of the earliest models of cell-Type specification by transcriptional activators and repressors. Remarkably, homothallic yeast cells can switch their Mating Type as often as every generation by a highly choreographed, site-specific homologous recombination event that replaces one MAT allele with different DNA sequences encoding the opposite MAT allele. This replacement process involves the participation of two intact but unexpressed copies of Mating-Type information at the heterochromatic loci, HMLα and HMRa, which are located at opposite ends of the same chromosome-encoding MAT. The study of MAT switching has yielded important insights into the control of cell lineage, the silencing of gene expression, the formation of heterochromatin, and the regulation of accessibility of the donor sequences. Real-time analysis of MAT switching has provided the most detailed description of the molecular events that occur during the homologous recombinational repair of a programmed double-strand chromosome break.
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Switching of Saccharomyces cerevisiae Mating-Type Genes
Mobile DNA II, 2002Co-Authors: James E. HaberAbstract:Homothallic switching of the budding yeast Mating-Type (MAT) genes has provided one of the most intensively studied examples of a programmed genetic rearrangement. A site-specific double-strand break (DSB) at the MAT locus, induced by HO endonuclease, provokes the replacement of Mating-Type specific sequences through homologous recombination. Homothallic organisms have the capacity to self-diploidize by converting some offspring of a haploid cell of one Mating Type to cells of the opposite Mating Type. This chapter briefly looks at the determination of cell lineage and at the mechanism of silencing the donor sequences. The conversion of one Mating Type to the other involves the replacement at the MAT locus of Ya or Yα by a gene conversion induced by a DSB. Additional information has been gleaned from the analysis of DSB-induced recombination in meiotic cells. Saccharomyces cerevisiae has evolved an elaborate mechanism that gives it the ability to choose between its two donors. It makes sense that MATa should seek out and recombine with HMLα rather than HMRa, so that the recombinational repair of the DSB will lead to a switch to the opposite Mating Type. By comparing the recombination enhancer (RE) sequences of S. cerevisiae and S. carlsbergensis (which is functional in S. cerevisiae), it was possible to narrow down the RE to 270 contiguous base pairs in S. cerevisiae or 244 in S. carlsbergensis, within which are four well-conserved subdomains.
Jan Schirawski - One of the best experts on this subject based on the ideXlab platform.
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sex in smut fungi structure function and evolution of Mating Type complexes
Fungal Genetics and Biology, 2008Co-Authors: Guus Bakkeren, Jorg Kamper, Jan SchirawskiAbstract:Smut fungi are basidiomycete plant pathogens that pose a threat to many important cereal crops. In order to be pathogenic on plants, smut fungal cells of compatible Mating-Type need to fuse. Fusion and pathogenicity are regulated by two loci, a and b, which harbor conserved genes. The functions of the encoded Mating-Type complexes have been well-studied in the model fungus Ustilago maydis and will be briefly reviewed here. Sequence comparison of the Mating-Type loci of different smut and related fungi has revealed that these loci differ substantially in structure. These structural differences point to an evolution from tetrapolar to bipolar Mating behavior, which might have occurred several independent times during fungal speciation.
