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Genetics

Title:		Evolution of Mating Systems in Basidiomycetes and the Genetic Architecture Underlying Mating-Type Determination in the Yeast Leucosporidium scottii
Author(s):		Maia TM; Lopes ST; Almeida JM; Rosa LH; Sampaio JP; Goncalves P; Coelho MA;
Address:		"UCIBIO, REQUIMTE, Departamento de Ciencias da Vida, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal. Departamento de Microbiologia, Universidade Federal de Minas Gerais, Belo Horizonte, MG, 31270-901 Brazil. UCIBIO, REQUIMTE, Departamento de Ciencias da Vida, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal madc@fct.unl.pt"
Journal Title:		Genetics
Year:		2015
Volume:		20150714
Issue:		1
Page Number:		75 - 89
DOI:		10.1534/genetics.115.177717
ISSN/ISBN:		1943-2631 (Electronic) 0016-6731 (Print) 0016-6731 (Linking)
Abstract:		"In most fungi, sexual reproduction is bipolar; that is, two alternate sets of genes at a single mating-type (MAT) locus determine two mating types. However, in the Basidiomycota, a unique (tetrapolar) reproductive system emerged in which sexual identity is governed by two unlinked MAT loci, each of which controls independent mechanisms of self/nonself recognition. Tetrapolar-to-bipolar transitions have occurred on multiple occasions in the Basidiomycota, resulting, for example, from linkage of the two MAT loci into a single inheritable unit. Nevertheless, owing to the scarcity of molecular data regarding tetrapolar systems in the earliest-branching lineage of the Basidiomycota (subphylum Pucciniomycotina), it is presently unclear if the last common ancestor was tetrapolar or bipolar. Here, we address this question, by investigating the mating system of the Pucciniomycotina yeast Leucosporidium scottii. Using whole-genome sequencing and chromoblot analysis, we discovered that sexual reproduction is governed by two physically unlinked gene clusters: a multiallelic homeodomain (HD) locus and a pheromone/receptor (P/R) locus that is biallelic, thereby dismissing the existence of a third P/R allele as proposed earlier. Allele distribution of both MAT genes in natural populations showed that the two loci were in strong linkage disequilibrium, but independent assortment of MAT alleles was observed in the meiotic progeny of a test cross. The sexual cycle produces fertile progeny with similar proportions of the four mating types, but approximately 2/3 of the progeny was found to be nonhaploid. Our study adds to others in reinforcing tetrapolarity as the ancestral state of all basidiomycetes"
Keywords:		"Basidiomycota/genetics/*physiology Evolution, Molecular *Genes, Mating Type, Fungal Genome, Fungal Haploidy Linkage Disequilibrium Phylogeny Sequence Analysis, DNA Basidiomycota fungi mating type mating-type determination sexual reproduction;"
Notes:		"MedlineMaia, Teresa M Lopes, Susana T Almeida, Joao M G C F Rosa, Luiz H Sampaio, Jose Paulo Goncalves, Paula Coelho, Marco A eng Research Support, Non-U.S. Gov't 2015/07/17 Genetics. 2015 Sep; 201(1):75-89. doi: 10.1534/genetics.115.177717. Epub 2015 Jul 14"