期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2021
卷号：118
期号：38
DOI：10.1073/pnas.2101242118
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
Interspecies hybrids, for which mules are a common example, are sterile and therefore an evolutionary dead end. Hybrid sterility has been an obstacle to classical genetic analysis, predictive quantitative approaches, and attempts at strain improvement via breeding. Here, we overcame infertility by creating hybrid tetraploids of yeast species to allow continuous multigenerational breeding. Thus, by exploiting interspecific genetic diversity, we were able to create an unprecedented number of meiotic progenies with different combinations of traits. We showed that the offspring of different hybrids have extreme phenotypes, identified quantitative trait loci (QTLs) dependent of the mitochondria, and discovered QTLs that are uniquely generated in hybrids and for which the allelic variation has no phenotypic consequences in the parental species.
Hybrids between species can harbor a combination of beneficial traits from each parent and may exhibit hybrid vigor, more readily adapting to new harsher environments. Interspecies hybrids are also sterile and therefore an evolutionary dead end unless fertility is restored, usually via auto-polyploidisation events. In the
Saccharomyces genus, hybrids are readily found in nature and in industrial settings, where they have adapted to severe fermentative conditions. Due to their hybrid sterility, the development of new commercial yeast strains has so far been primarily conducted via selection methods rather than via further breeding. In this study, we overcame infertility by creating tetraploid intermediates of
Saccharomyces interspecies hybrids to allow continuous multigenerational breeding. We incorporated nuclear and mitochondrial genetic diversity within each parental species, allowing for quantitative genetic analysis of traits exhibited by the hybrids and for nuclear–mitochondrial interactions to be assessed. Using pooled F12 generation segregants of different hybrids with extreme phenotype distributions, we identified quantitative trait loci (QTLs) for tolerance to high and low temperatures, high sugar concentration, high ethanol concentration, and acetic acid levels. We identified QTLs that are species specific, that are shared between species, as well as hybrid specific, in which the variants do not exhibit phenotypic differences in the original parental species. Moreover, we could distinguish between mitochondria-type–dependent and –independent traits. This study tackles the complexity of the genetic interactions and traits in hybrid species, bringing hybrids into the realm of full genetic analysis of diploid species, and paves the road for the biotechnological exploitation of yeast biodiversity.
