Homothallism: an umbrella term for describing diverse sexual behaviours

Wilson, Andrea M.; Wilken, P. Markus; Nest, Magriet A. van der; Steenkamp, Emma Theodora; Wingfield, Michael J.; Wingfield, Brenda D.

doi:10.5598/imafungus.2015.06.01.13

Cited by 77 publications

(88 citation statements)

References 61 publications

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“…intrahaploid mating, same-clone mating, or haploid selfing) (156) (15, 79). We call these species homothallic, and several proximal mechanisms have been proposed to account for such mating behavior, namely: (i) the presence of compatible sets of MAT genes, either fused or unlinked, in one haploid genome (primary homothallism); (ii) mating-type switching (either bidirectional or unidirectional); and (iii) the lack of any gene-based mating-type discrimination (also known as ability for unisexual reproduction or same-sex mating) [reviewed in (157, 158)]. Some other fungal species, referred to as pseudohomothallic, also have the ability to complete the sexual cycle without the apparent need for syngamy (159–161).…”

Section: Breeding Systems In the Basidiomycotamentioning

confidence: 99%

Fungal Sex: The Basidiomycota

et al. 2017

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SUMMARY Fungi of the Basidiomycota, representing major pathogen lineages and mushroom-forming species, exhibit diverse means to achieve sexual reproduction, with particularly varied mechanisms to determine compatibilities of haploid mating partners. For species that require mating between distinct genotypes, discrimination is usually based on both the reciprocal exchange of diffusible mating pheromones, rather than sexes, and the interactions of homeodomain protein signals after cell fusion. Both compatibility factors must be heterozygous in the product of mating, and genetic linkage relationships of the mating pheromone/receptor and homeodomain genes largely determine the complex patterns of mating-type variation. Independent segregation of the two compatibility factors can create four haploid mating genotypes from meiosis, referred to as tetrapolarity. This condition is thought to be ancestral to the basidiomycetes. Alternatively, co-segregation by linkage of the two mating factors, or in some cases the absence of the pheromone-based discrimination, yields only two mating types from meiosis, referred to as bipolarity. Several species are now known to have large and highly rearranged chromosomal regions linked to mating-type genes. At the population level, polymorphism of the mating-type genes is an exceptional aspect of some basidiomycete fungi, where selection under outcrossing for rare, intercompatible allelic variants is thought to be responsible for mating types that may number several thousand. Advances in genome sequencing and assembly are yielding new insights by comparative approaches among and within basidiomycete species, with the promise to resolve the evolutionary origins and dynamics of mating compatibility genetics in this major eukaryotic lineage.

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Section: Breeding Systems In the Basidiomycotamentioning

confidence: 99%

Fungal Sex: The Basidiomycota

et al. 2017

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“…At the cellular level there are two very different forms of homothallism: primary and secondary (Lin and Heitman 2007; Almeida et al 2015; Inderbitzin and Turgeon 2015; Wilson et al 2015). In primary homothallic species, any cell can mate with any other cell.…”

Section: Heterothallism and Two Types Of Homothallismmentioning

confidence: 99%

An Evolutionary Perspective on Yeast Mating-Type Switching

2017

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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?

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“…Some B. cinerea isolates fertile with both MAT1-1 and MAT1-2 strains, and often self-fertile (MAT1-1/2), referred to as pseudohomothallic (Faretra & Grindle, 1992) or dual maters (Amselem et al, 2011), were first detected by Lorenz & Eichhorn (1983) in Germany, and then reported in Europe and other countries (Faretra et al, 1988b;Beever & Parkes, 1993;Faretra & Pollastro, 1993;van der Vlugt-Bergmans et al, 1993;Delc an & Melgarejo, 2002). Several mechanisms are responsible for homothallic behaviour in heterothallic fungi, such as heterokaryosis, regular inclusion of nuclei having opposite mating types in single ascospores, coexistence of both idiomorphs in heteroploid isolates, transposition of the MAT genes and unisexuality (Roach et al, 2014;Wilson et al, 2015). In B. cinerea, heterokaryosis appears to be the main cause of pseudohomothallism of field and monoconidial isolates, as it has been shown that single multinucleate conidia may contain nuclei carrying opposite idiomorphs (Faretra et al, 1988b).…”

Section: Introductionmentioning

confidence: 99%

Molecular analysis of the mating type (MAT1) locus in strains of the heterothallic ascomycete Botrytis cinerea

et al. 2016

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Botrytis cinerea shows a heterothallic bipolar mating‐type system; homothallism has been occasionally observed. MAT1 genes and flanking regions in the reference strains SAS56 (MAT1‐1) and SAS405 (MAT1‐2) and their monoascosporic progeny were analysed. The two mating types confirmed different sequences of 2513 bp (MAT1‐1) and 2776 bp (MAT1‐2), flanked by near identical regions. In all isolates, each idiomorph included two mating‐type specific genes: MAT1‐1‐1 (1161 bp), encoding an alpha‐domain containing protein, and MAT1‐1‐5 (1301 bp); or MAT1‐2‐1 (1236 bp), encoding a HMG‐domain protein, and MAT1‐2‐4 (712 bp); the latter genes encode putative proteins of unknown function. Truncated MAT1‐1‐1 (670 bp) and MAT1‐2‐1 (92 bp) sequences of the opposite mating‐type were found in the flanking regions. Idiomorph‐specific PCR primer pairs were used to explore the structure of the MAT1 locus in ascospore progeny and field isolates showing homothallic behaviour, and the locus organization in all of them did not differ from that of heterothallic strains. Constitutive expression of all the four mating‐type genes was ascertained by RT‐PCR at four different developmental stages (mycelium, sclerotia at two different stages and apothecia). Antisense transcription of the MAT1‐2‐1 gene with isoforms from alternative splicing was detected. Comparative analysis of MAT1 loci in B. cinerea and in the closely related homothallic Sclerotinia sclerotiorum led to the identification of short nearly identical sequences.

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Homothallism: an umbrella term for describing diverse sexual behaviours

Cited by 77 publications

References 61 publications

Fungal Sex: The Basidiomycota

Fungal Sex: The Basidiomycota

An Evolutionary Perspective on Yeast Mating-Type Switching

Molecular analysis of the mating type (MAT1) locus in strains of the heterothallic ascomycete Botrytis cinerea

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