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Dominant Epistasis Between Two Quantitative Trait Loci Governing Sporulation Efficiency in Yeast Saccharomyces cerevisiae

Juraj Bergman1, Petar T. Mitrikeski1,2 and Krunoslav Brčić-Kostić1*

1Laboratory for Evolutionary Genetics, Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54,
  HR-10000 Zagreb, Croatia
2Institute for Research and Development of Sustainable Ecosystems, Faculty of Veterinary Medicine, Heinzelova 55,
  HR-10000 Zagreb, Croatia

Article history:
Received November 18, 2014
Accepted July 3, 2015

Key words
budding yeast, sporulation inheritance, two-locus epistasis, QTL analysis, phenotype 

Sporulation efficiency in the yeast Saccharomyces cerevisiae is a well-established model for studying quantitative traits. A variety of genes and nucleotides causing different sporulation efficiencies in laboratory, as well as in wild strains, has already been extensively characterised (mainly by reciprocal hemizygosity analysis and nucleotide exchange methods). We applied a different strategy in order to analyze the variation in sporulation efficiency of laboratory yeast strains. Coupling classical quantitative genetic analysis with simulations of phenotypic distributions (a method we call phenotype modelling) enabled us to obtain a detailed picture of the quantitative trait loci (QTLs) relationships underlying the phenotypic variation of this trait. Using this approach, we were able to uncover a dominant epistatic inheritance of loci governing the phenotype. Moreover, a molecular analysis of known causative quantitative trait genes and nucleotides allowed for the detection of novel all molecular data, we hypothesise that the observed dominant epistatic relationship could be caused by the interaction of multiple quantitative trait nucleotides distributed across a 60-kb QTL region located on chromosome XIV and the RME1 locus on chromosome VII. Furthermore, we propose a model of molecular pathways which possibly underlie the phenotypic variation of this trait.

*Corresponding author:  email2   This email address is being protected from spambots. You need JavaScript enabled to view it.   
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Contributions: This study was suggested by KBK, and further developed by KBK and PTM. Experimental design is by PTM and KBK. All the experiments were executed by JB. The computational analysis was suggested and designed by JB, as well as the molecular model. The manuscript was conceived and writt en by JB, PTM and KB