Allodiploidization is a fundamental yet evolutionary poorly characterized event, which impacts genome evolution and heredity, controlling organismal development and polyploid cell-types. In this study, we investigated the sex determination system in the allodiploid and sterile ATCC 42981 yeast, a member of the Zygosaccharomyces rouxii species complex, and used it to study how a chimeric mating-type gene repertoire contributes to hybrid reproductive isolation. We found that ATCC 42981 has 7 MAT-like (MTL) loci, 3 of which encode α-idiomorph and 4 encode a-idiomorph. Two phylogenetically divergent MATexpression loci were identified on different chromosomes, accounting for a hybrid a/α genotype. Furthermore, extra a-idimorph-encoding loci (termed MTLa copies 1 to 3) were recognized, which shared the same MATa1 ORFs but diverged forMATa2 genes. Each MATexpression locus was linked to a HML silent cassette, while the corresponding HMR loci were located on another chromosome. Two putative parental sex chromosome pairs contributed to this unusual genomic architecture: one came from an as-yet-undescribed taxon, which has the NCYC 3042 strain as a unique representative, while the other did not match any MAT-HML and HMR organizations previously described in Z. rouxii species. This chimeric rearrangement produces two copies of the HO gene, which encode for putatively functional endonucleases essential for mating-type switching. Although both a and a coding sequences, which are required to obtain a functional cell-type a1-α2 regulator, were present in the allodiploid ATCC 42981 genome, the transcriptional circuit, which regulates entry into meiosis in response to meiosis-inducing salt stress, appeared to be turned off. Furthermore, haploid and a-specific genes, such as MATα1 and HO, were observed to be actively transcribed and up-regulated under hypersaline stress. Overall, these evidences demonstrate that ATCC 42981 is unable to repress haploid a-specific genes and to activate meiosis in response to stress. We argue that sequence divergence within the chimeric a1-α2 heterodimer could be involved in the generation of negative epistasis, contributing to the allodiploid sterility and the dysregulation of cell identity.
Chimeric sex-determining chromosomal regions and dysregulation of cell-type identity in a sterile zygosaccharomyces allodiploid yeast / Bizzarri, Melissa; Giudici, P.; Cassanelli, S.; Solieri, L.. - In: PLOS ONE. - ISSN 1932-6203. - 11:4(2016), pp. 1-23. [10.1371/journal.pone.0152558]
|Data di pubblicazione:||2016|
|Titolo:||Chimeric sex-determining chromosomal regions and dysregulation of cell-type identity in a sterile zygosaccharomyces allodiploid yeast|
|Autore/i:||Bizzarri, Melissa; Giudici, P.; Cassanelli, S.; Solieri, L.|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1371/journal.pone.0152558|
|Codice identificativo ISI:||WOS:000373891000012|
|Codice identificativo Scopus:||2-s2.0-84963764651|
|Codice identificativo Pubmed:||27065237|
|Citazione:||Chimeric sex-determining chromosomal regions and dysregulation of cell-type identity in a sterile zygosaccharomyces allodiploid yeast / Bizzarri, Melissa; Giudici, P.; Cassanelli, S.; Solieri, L.. - In: PLOS ONE. - ISSN 1932-6203. - 11:4(2016), pp. 1-23. [10.1371/journal.pone.0152558]|
|Tipologia||Articolo su rivista|
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