Flor Yeasts Rewire the Central Carbon Metabolism During Wine Alcoholic Fermentation.

Emilien Peltier,Omar Abou Saada,Anne Friedrich,Charlotte Vion,Philippe Marullo,Joseph Schacherer

doi:10.3389/ffunb.2021.733513

Abstract

The identification of natural allelic variations controlling quantitative traits could contribute to decipher metabolic adaptation mechanisms within different populations of the same species. Such variations could result from human-mediated selection pressures and participate to the domestication. In this study, the genetic causes of the phenotypic variability of the central carbon metabolism of Saccharomyces cerevisiae were investigated in the context of the enological fermentation. The genetic determinism of this trait was found out by a quantitative trait loci (QTL) mapping approach using the offspring of two strains belonging to the wine genetic group of the species. A total of 14 QTL were identified from which 8 were validated down to the gene level by genetic engineering. The allelic frequencies of the validated genes within 403 enological strains showed that most of the validated QTL had allelic variations involving flor yeast specific alleles. Those alleles were brought in the offspring by one parental strain that contains introgressions from the flor yeast genetic group. The causative genes identified are functionally linked to quantitative proteomic variations that would explain divergent metabolic features of wine and flor yeasts involving the tricarboxylic acid cycle (TCA), the glyoxylate shunt and the homeostasis of proton and redox cofactors. Overall, this work led to the identification of genetic factors that are hallmarks of adaptive divergence between flor yeast and wine yeast in the wine biotope. These results also reveal that introgressions originated from intraspecific hybridization events promoted phenotypic variability of carbon metabolism observed in wine strains.

Highlights

Deciphering how the considerable phenotypic diversity observed at the species level is controlled by genetic variation is an important and non-trivial goal in biology
In order to explore the genetic determinism of central carbon metabolism during wine alcoholic fermentation, the previous dataset of fermentation traits measured within a quantitative trait loci (QTL) mapping population was used (Peltier et al, 2018b)
Glycerol and CO2 are de novo synthetized by yeast catabolism; their concentrations are expressed in g/L

Summary

Introduction

Deciphering how the considerable phenotypic diversity observed at the species level is controlled by genetic variation is an important and non-trivial goal in biology. Unraveling the genetic basis of adaptation highlights how organisms adapt to new selection pressures triggered by climate change, new pathogens or drugs and vaccines (Olson-Manning et al, 2012; Alföldi and Lindblad-Toh, 2013). Domesticated organisms are a great opportunity to study adaptation as there is a better knowledge of their adaptive history through their wellcharacterized phenotypic properties and selective environments (Ross-Ibarra et al, 2007; Gladieux et al, 2014). The identification of genes and molecular mechanisms leading to adaptation against domestication is very useful in genetic selection in order to improve traits of economic interest and bringing phenotypic novelty to domesticated species (McCouch, 2004)

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