Genetic interactions contribute less than additive effects to quantitative trait variation in yeast

• Published in: Nature communications Vol. 6; no. 1; p. 8712
• Main Authors: Bloom, Joshua S, Kotenko, Iulia, Sadhu, Meru J, Treusch, Sebastian, Albert, Frank W, Kruglyak, Leonid
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 05.11.2015; Nature Pub. Group
• Subjects: Chromosome Mapping; Epistasis, Genetic; Genetic Variation; Genotype; Phenotype; Quantitative Trait Loci; Saccharomyces cerevisiae - genetics
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms9712

Genetic mapping studies of quantitative traits typically focus on detecting loci that contribute additively to trait variation. Genetic interactions are often proposed as a contributing factor to trait variation, but the relative contribution of interactions to trait variation is a subject of debate. Here we use a very large cross between two yeast strains to accurately estimate the fraction of phenotypic variance due to pairwise QTL-QTL interactions for 20 quantitative traits. We find that this fraction is 9% on average, substantially less than the contribution of additive QTL (43%). Statistically significant QTL-QTL pairs typically have small individual effect sizes, but collectively explain 40% of the pairwise interaction variance. We show that pairwise interaction variance is largely explained by pairs of loci at least one of which has a significant additive effect. These results refine our understanding of the genetic architecture of quantitative traits and help guide future mapping studies.