scholarly journals Altered mating-type identity in the fungus Podospora anserina leads to selfish nuclei, uniparental progeny, and haploid meiosis.

Genetics ◽  
1995 ◽  
Vol 140 (2) ◽  
pp. 493-503 ◽  
Author(s):  
D Zickler ◽  
S Arnaise ◽  
E Coppin ◽  
R Debuchy ◽  
M Picard
Keyword(s):  
Mating Type ◽  
Podospora Anserina ◽  
Wild Type ◽  
Selfish Behavior ◽  
Developmental Patterns ◽  
Filamentous Ascomycete ◽  
Type Identity ◽  
Mat Locus ◽  
Mat Genes

Abstract In wild-type crosses of the filamentous ascomycete Podospora anserina, after fertilization, only nuclei of opposite mating type can form dikaryons that undergo karyogamy and meiosis, producing biparental progeny. To determine the role played by the mating type in these steps, the four mat genes were mutagenized in vitro and introduced into a strain deleted for its mat locus. Genetic and cytological analyses of these mutant strain, crossed to each other and to wild type, showed that mating-type information is required for recognition of nuclear identity during the early steps of sexual reproduction. In crosses with strain carrying a mating-type mutation, two unusual developmental patterns were observed: monokaryotic cells, resulting in haploid meiosis, and uniparental dikaryotic cells providing, after karyogamy and meiosis, a uniparental progeny. Altered mating-type identity leads to selfish behavior of the mutant nucleus: it migrates alone or paired, ignoring its wild-type partner in all mutant x wild-type crosses. This behavior is nucleus-autonomous because, in the same cytoplasm, the wild-type nuclei form only biparental dikaryons. In P. anserina, mat genes are thus required to ensure a biparental dikaryotic state but appear dispensable for later stages, such as meiosis and sporulation.

scholarly journals Deletion and Complementation of the Mating Type (MAT) Locus of the Wheat Head Blight Pathogen Gibberella zeae

2004 ◽  
Vol 70 (4) ◽  
pp. 2437-2444 ◽  
Author(s):  
A. E. Desjardins ◽  
D. W. Brown ◽  
S.-H. Yun ◽  
R. H. Proctor ◽  
T. Lee ◽  
...  
Keyword(s):  
Mating Type ◽  
Wild Type Strain ◽  
Direct Injection ◽  
Gibberella Zeae ◽  
Wild Type ◽  
Head Blight ◽  
Filamentous Ascomycete ◽  
Novel Approaches ◽  
Mat Locus ◽  
Greenhouse Tests

ABSTRACT Gibberella zeae, a self-fertile, haploid filamentous ascomycete, causes serious epidemics of wheat (Triticum aestivum) head blight worldwide and contaminates grain with trichothecene mycotoxins. Anecdotal evidence dating back to the late 19th century indicates that G. zeae ascospores (sexual spores) are a more important inoculum source than are macroconidia (asexual spores), although the fungus can produce both during wheat head blight epidemics. To develop fungal strains to test this hypothesis, the entire mating type (MAT1) locus was deleted from a self-fertile (MAT1-1/MAT1-2), virulent, trichothecene-producing wild-type strain of G. zeae. The resulting MAT deletion (mat1-1/mat1-2) strains were unable to produce perithecia or ascospores and appeared to be unable to mate with the fertile strain from which they were derived. Complementation of a MAT deletion strain by transformation with a copy of the entire MAT locus resulted in recovery of production of perithecia and ascospores. MAT deletion strains and MAT-complemented strains retained the ability to produce macroconidia that could cause head blight, as assessed by direct injection into wheat heads in greenhouse tests. Availability of MAT-null and MAT-complemented strains provides a means to determine the importance of ascospores in the biology of G. zeae and perhaps to identify novel approaches to control wheat head blight.

scholarly journals Co-expression of the Mating-Type Genes Involved in Internuclear Recognition Is Lethal in Podospora anserina

Genetics ◽  
2000 ◽  
Vol 155 (2) ◽  
pp. 657-669 ◽  
Author(s):  
Evelyne Coppin ◽  
Robert Debuchy
Keyword(s):  
Mating Type ◽  
Transcriptional Control ◽  
Wild Type Strain ◽  
Podospora Anserina ◽  
Wild Type ◽  
Initial Development ◽  
Genes Encoding ◽  
In The Wild ◽  
Mating Type Genes ◽  
Mat Genes

Abstract In the heterothallic filamentous fungus Podospora anserina, four mating-type genes encoding transcriptional factors have been characterized: FPR1 in the mat+ sequence and FMR1, SMR1, and SMR2 in the alternative mat− sequence. Fertilization is controlled by FPR1 and FMR1. After fertilization, male and female nuclei, which have divided in the same cell, form mat+/mat− pairs during migration into the ascogenous hyphae. Previous data indicate that the formation of mat+/mat− pairs is controlled by FPR1, FMR1, and SMR2. SMR1 was postulated to be necessary for initial development of ascogenous hyphae. In this study, we investigated the transcriptional control of the mat genes by seeking mat transcripts during the vegetative and sexual phase and fusing their promoter to a reporter gene. The data indicate that FMR1 and FPR1 are expressed in both mycelia and perithecia, whereas SMR1 and SMR2 are transcribed in perithecia. Increased or induced vegetative expression of the four mat genes has no effect when the recombined gene is solely in the wild-type strain. However, the combination of resident FPR1 with deregulated SMR2 and overexpressed FMR1 in the same nucleus is lethal. This lethality is suppressed by the expression of SMR1, confirming that SMR1 operates downstream of the other mat genes.

Mating-type genes control sexual reproduction, conidial germination and virulence in Cochliobolus lunatus

2021 ◽  
Author(s):  
Kexin Liu ◽  
Jiaqi Jia ◽  
Nan Chen ◽  
Dandan Fu ◽  
Jiaying Sun ◽  
...  
Keyword(s):  
Mating Type ◽  
Pathogenic Fungus ◽  
Germination Rate ◽  
Dry Weight ◽  
Single Copy ◽  
Conidial Germination ◽  
Curvularia Lunata ◽  
Wild Type ◽  
Cochliobolus Lunatus ◽  
Mat Genes

Cochliobolus lunatus (anamorph: Curvularia lunata) is a major pathogenic fungus that causes the Curvularia leaf spot of maize. ClMAT1-1-1 and ClMAT1-2-1, the C. lunatus orthologs of Cochliobolus heterostrophus ChMAT1-1-1 and ChMAT1-2-1, were investigated in the present study to uncover their functions in C. lunatus. Southern blot analysis showed that these mating-type MAT genes exist in the C. lunatus genome as a single copy. ClMAT1-1-1 and ClMAT1-2-1 were knocked out and complemented to generate ΔClmat1-1-1 and ΔClmat1-2-1, ΔClmat1-1-1-C and ΔClmat1-2-1-C, respectively. The mutant strains had defective sexual development and failed to produce pseudothecia. There were no significant differences in growth rate or conidia production between the mutant and wild-type strains. However, the aerial mycelia and mycelial dry weight of ΔClmat1-1-1 and ΔClmat1-2-1 were lower than that of wild type, suggesting that MAT genes affect asexual development. ClMAT genes were involved in the responses to cell wall integrity and osmotic adaptation. ΔClmat1-2-1 had a lower conidial germination rate than the wild-type strain CX-3. The virulence of ΔClmat1-2-1 and ΔClmat1-1-1 was also reduced compared to the wild type. Complementary strains could restore all the phenotypes.

Mating types and sexual development in filamentous ascomycetes

1997 ◽  
Vol 61 (4) ◽  
pp. 411-428 ◽  
Author(s):  
E Coppin ◽  
R Debuchy ◽  
S Arnaise ◽  
M Picard
Keyword(s):  
Mating Type ◽  
Sexual Development ◽  
Single Species ◽  
Podospora Anserina ◽  
Type Model ◽  
Mating Types ◽  
Dna Binding Domains ◽  
Binding Domains ◽  
Hormonal Signal ◽  
Mat Genes

The progress made in the molecular characterization of the mating types in several filamentous ascomycetes has allowed us to better understand their role in sexual development and has brought to light interesting biological problems. The mating types of Neurospora crassa, Podospora anserina, and Cochliobolus heterostrophus consist of unrelated and unique sequences containing one or several genes with multiple functions, related to sexuality or not, such as vegetative incompatibility in N. crassa. The presence of putative DNA binding domains in the proteins encoded by the mating-type (mat) genes suggests that they may be transcriptional factors. The mat genes play a role in cell-cell recognition at fertilization, probably by activating the genes responsible for the hormonal signal whose occurrence was previously demonstrated by physiological experiments. They also control recognition between nuclei at a later stage, when reproductive nuclei of each mating type which have divided in the common cytoplasm pair within the ascogenous hyphae. How self is distinguished from nonself at the nuclear level is not known. The finding that homothallic species, able to mate in the absence of a partner, contain both mating types in the same haploid genome has raised more issues than it has resolved. The instability of the mating type, in particular in Sclerotinia trifolorium and Botrytinia fuckeliana, is also unexplained. This diversity of mating systems, still more apparent if the yeasts and the basidiomycetes are taken into account, clearly shows that no single species can serve as a universal mating-type model.

scholarly journals Cloning the mating types of the heterothallic fungus Podospora anserina: developmental features of haploid transformants carrying both mating types.

Genetics ◽  
1991 ◽  
Vol 128 (3) ◽  
pp. 539-547 ◽  
Author(s):  
M Picard ◽  
R Debuchy ◽  
E Coppin
Keyword(s):  
Mating Type ◽  
Gene Replacement ◽  
Podospora Anserina ◽  
The Other ◽  
Mating Types ◽  
Body Development ◽  
Fruiting Body Development ◽  
Mat Locus ◽  
Functional Analyses ◽  
Developmental Features

Abstract DNAs that encode the mating-type functions (mat+ and mat-) of the filamentous fungus Podospora anserina were cloned with the use of the mating-type A probe from Neurospora crassa. Cloning the full mat information was ascertained through gene replacement experiments. Molecular and functional analyses of haploid transformants carrying both mating types lead to several striking conclusions. Mat+ mat- strains are dual maters. However, the resident mat information is dominant to the mat information added by transformation with respect to fruiting body development and ascus production. Moreover, when dual mating mat+ mat- strains are crossed to mat+ or mat- testers, there is strong selection, after fertilization, that leads to the loss from the mat+ mat- nucleus of the mat information that matches that of the tester. Finally, the mat locus contains at least two domains, one sufficient for fertilization, the other necessary for sporulation.

scholarly journals Mating-Type Gene Structure and Spatial Distribution of Didymella tanaceti in Pyrethrum Fields

2016 ◽  
Vol 106 (12) ◽  
pp. 1521-1529 ◽  
Author(s):  
Tamieka L. Pearce ◽  
Jason B. Scott ◽  
Frank S. Hay ◽  
Sarah J. Pethybridge
Keyword(s):  
Spatial Distribution ◽  
Mating Type ◽  
Tan Spot ◽  
Mating Types ◽  
Tanacetum Cinerariifolium ◽  
Polymerase Chain ◽  
Type Gene ◽  
Mat Genes

Tan spot of pyrethrum (Tanacetum cinerariifolium) is caused by the ascomycete Didymella tanaceti. To assess the evolutionary role of ascospores in the assumed asexual species, the structure and arrangement of mating-type (MAT) genes were examined. A single MAT1-1 or MAT1-2 idiomorph was identified in all isolates examined, indicating that the species is heterothallic. The idiomorphs were flanked upstream and downstream by regions encoding pyridoxamine phosphate oxidase-like and DNA lyase-like proteins, respectively. A multiplex MAT-specific polymerase chain reaction assay was developed and used to genotype 325 isolates collected within two transects in each of four fields in Tasmania, Australia. The ratio of isolates of each mating-type in each transect was consistent with a 1:1 ratio. The spatial distribution of the isolates of the two mating-types within each transect was random for all except one transect for MAT1-1 isolates, indicating that clonal patterns of each mating-type were absent. However, evidence of a reduced selection pressure on MAT1-1 isolates was observed, with a second haplotype of the MAT1-1-1 gene identified in 4.4% of MAT1-1 isolates. In vitro crosses between isolates with opposite mating-types failed to produce ascospores. Although the sexual morph could not be induced, the occurrence of both mating-types in equal frequencies suggested that a cryptic sexual mode of reproduction may occur within field populations.

scholarly journals Mutations in Mating-Type Genes of the Heterothallic Fungus Podospora anserina Lead to Self-Fertility

Genetics ◽  
2001 ◽  
Vol 159 (2) ◽  
pp. 545-556
Author(s):  
Sylvie Arnaise ◽  
Denise Zickler ◽  
Suzanne Le Bilcot ◽  
Corinne Poisier ◽  
Robert Debuchy
Keyword(s):  
Mating Type ◽  
Type Strain ◽  
Wild Type Strain ◽  
Male Partner ◽  
Podospora Anserina ◽  
Wild Type ◽  
Opposite Mating Type ◽  
Initial Development ◽  
Mating Type Genes ◽  
Further Development

Abstract The heterothallic fungus Podospora anserina has two mating-type alleles termed mat+ and mat−. The mat+ sequence contains one gene, FPR1, while mat− contains three genes: FMR1, SMR1, and SMR2. FPR1 and FMR1 are required for fertilization, which is followed by mitotic divisions of the two parental nuclei inside the female organ. This leads to the formation of plurinucleate cells containing a mixture of parental mat+ and mat− nuclei. Further development requires a recognition between mat+ and mat− nuclei before migration of the mat+/mat− pairs into specialized hyphae in which karyogamy, meiosis, and ascospore formation take place. FPR1, FMR1, and SMR2 control this internuclear recognition step. Initial development of the dikaryotic stage is supposed to require SMR1; disruption of SMR1 results in barren perithecia. In a systematic search for suppressors restoring fertility, we isolated 15 suppressors—all of them mutations in the mating-type genes. These fmr1, smr2, and fpr1 mutants, as well as the strains disrupted for FMR1, SMR2, and FPR1, are weakly self-fertile. They are able to act as the male partner on a strain of the same mating type and give a mixture of biparental and uniparental progeny when crossed with a wild-type strain of opposite mating type. These observations lead us to propose that SMR2, FMR1, and FPR1 act as activators and repressors of fertilization and internuclear recognition functions.

Structure and function of mating type genes in Cochliobolus spp. and asexual fungi

1995 ◽  
Vol 73 (S1) ◽  
pp. 778-783 ◽  
Author(s):  
B. Gillian Turgeon ◽  
Amir Sharon ◽  
Stefan Wirsel ◽  
Kenichi Yamaguchi ◽  
Solveig K. Christiansen ◽  
...  
Keyword(s):  
Mating Type ◽  
Opposite Mating Type ◽  
Asexual Fungi ◽  
Mating Type Genes ◽  
Type Gene ◽  
And Function ◽  
Mat Locus ◽  
Mat Genes ◽  
Mat Gene ◽  
Transgenic Strains

Mating type (MAT) genes of Cochliobolus heterostrophus have homologs in other heterothallic Cochliobolus spp., in homothallic Cochliobolus spp., and in asexual fungi thought to be taxonomically related to Cochliobolus (e.g., Bipolaris spp.). To examine the cause of asexuality in B. sacchari, its homolog of C. heterostrophus MAT-2 was cloned. The B. sacchari sequence was 98% identical to that of C. heterostrophus MAT-2, the gene conferred homothallism when expressed in a C. heterostrophus MAT-1 strain, and transgenic strains mated with C. heterostrophus MAT-1. Thus the cause of asexuality in B. sacchari is not absence or lack of a functional MAT gene. When the C. heterostrophus MAT genes were expressed in B. sacchari, however, no sexual development occurred, suggesting that this asexual fungus lacks an attribute, other than the mating type gene, which is required for mating. Although cloned MAT genes function upon transformation into recipient strains, they do not confer full fertility. When an homologous or heterologous (e.g., from C. carbonum, C. victoriae, or B. sacchari) MAT gene is transferred into a C. heterostrophus strain of opposite mating type, the strain can self and cross to tester strains of either mating type. However, any transgenic strain carrying both a resident MAT gene and an homologous or heterologous MAT transgene develops normal perithecia but few ascospores in a cross that requires function of the transgene. To determine if the resident MAT gene interferes with function of the transgene, the MAT locus was deleted from the genome of C. heterostrophus and then replaced with the MAT gene of C. heterostrophus, C. carbonum, C. victoriae, or B. sacchari. Interference was eliminated and abundant ascospores were formed when the four transgenic strains were crossed to C. heterostrophus strains of opposite mating type. Key words: asexual fungi, DNA-binding proteins, heterologous expression, transformation.

scholarly journals Pistil Mating Type and Morphology Are Mediated by the Brassinosteroid Inactivating Activity of the S-Locus Gene BAHD in Heterostylous Turnera Species

2021 ◽  
Vol 22 (19) ◽  
pp. 10603
Author(s):  
Courtney M. Matzke ◽  
Hasan J. Hamam ◽  
Paige M. Henning ◽  
Kyra Dougherty ◽  
Joel S. Shore ◽  
...  
Keyword(s):  
Mating Type ◽  
Mutant Allele ◽  
Mating Types ◽  
Self Incompatibility ◽  
S Locus ◽  
Wild Type ◽  
Truncated Protein ◽  
Conserved Domain ◽  
Pistil Length

Heterostyly is a breeding system that promotes outbreeding through a combination of morphological and physiological floral traits. In Turnera these traits are governed by a single, hemizygous S-locus containing just three genes. We report that the S-locus gene, BAHD, is mutated and encodes a severely truncated protein in a self-compatible long homostyle species. Further, a self-compatible long homostyle mutant possesses a T. krapovickasii BAHD allele with a point mutation in a highly conserved domain of BAHD acyl transferases. Wild type and mutant TkBAHD alleles were expressed in Arabidopsis to assay for brassinosteroid (BR) inactivating activity. The wild type but not mutant allele caused dwarfism, consistent with the wild type possessing, but the mutant allele having lost, BR inactivating activity. To investigate whether BRs act directly in self-incompatibility, BRs were added to in vitro pollen cultures of the two mating types. A small morph specific stimulatory effect on pollen tube growth was found with 5 µM brassinolide, but no genotype specific inhibition was observed. These results suggest that BAHD acts pleiotropically to mediate pistil length and physiological mating type through BR inactivation, and that in regard to self-incompatibility, BR acts by differentially regulating gene expression in pistils, rather than directly on pollen.

The URNA Genes of Herpesvirus Saimiri (Strain C488) Are Dispensable for Transformation of Human T Cells In Vitro

1999 ◽  
Vol 73 (12) ◽  
pp. 10551-10555 ◽  
Author(s):  
Armin Ensser ◽  
André Pfinder ◽  
Ingrid Müller-Fleckenstein ◽  
Bernhard Fleckenstein
Keyword(s):  
Cell Culture ◽  
Herpesvirus Saimiri ◽  
Wild Type Virus ◽  
Type Virus ◽  
Wild Type ◽  
Human T Cell ◽  
Human T Cells ◽  
Small Nuclear Rnas ◽  
T Cell Lines

ABSTRACT The herpesvirus saimiri strain C488 genome contains five genes for small nuclear RNAs, termed herpesvirus saimiri URNAs (or HSURs). Using a cosmid-based approach, all HSURs were precisely deleted from the genome. The mutant virus replicated at levels that were similar to those of wild-type viruses in OMK cells. Although the HSURs are expressed in wild-type virus-transformed human T-cell lines, the deletion does not affect viral transformation in cell culture.

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