QTL mapping of the production of wine aroma compounds by yeast

Abstract

BackgroundWine aroma results from the combination of numerous volatile compounds, some produced by yeast and others produced in the grapes and further metabolized by yeast. However, little is known about the consequences of the genetic variation of yeast on the production of these volatile metabolites, or on the metabolic pathways involved in the metabolism of grape compounds. As a tool to decipher how wine aroma develops, we analyzed, under two experimental conditions, the production of 44 compounds by a population of 30 segregants from a cross between a laboratory strain and an industrial strain genotyped at high density.ResultsWe detected eight genomic regions explaining the diversity concerning 15 compounds, some produced de novo by yeast, such as nerolidol, ethyl esters and phenyl ethanol, and others derived from grape compounds such as citronellol, and cis-rose oxide. In three of these eight regions, we identified genes involved in the phenotype. Hemizygote comparison allowed the attribution of differences in the production of nerolidol and 2-phenyl ethanol to the PDR8 and ABZ1 genes, respectively. Deletion of a PLB2 gene confirmed its involvement in the production of ethyl esters. A comparison of allelic variants of PDR8 and ABZ1 in a set of available sequences revealed that both genes present a higher than expected number of non-synonymous mutations indicating possible balancing selection.ConclusionsThis study illustrates the value of QTL analysis for the analysis of metabolic traits, and in particular the production of wine aromas. It also identifies the particular role of the PDR8 gene in the production of farnesyldiphosphate derivatives, of ABZ1 in the production of numerous compounds and of PLB2 in ethyl ester synthesis. This work also provides a basis for elucidating the metabolism of various grape compounds, such as citronellol and cis-rose oxide.

Differential adaptation to multi-stressed conditions of wine fermentation revealed by variations in yeast regulatory networks

“…We detected variation of expression for very few genes (adjPv<0.01, Table 4). QDR2 was the gene most strongly upregulated by allelic replacement, with a LogFC of 2.24, consistent with the results of Steyer et al [32]. Among the other targets of PDR8 , we only found YLR179c controlled by the allelic form of PDR8 .…”

Determination of Sesquiterpenes in Wines by HS-SPME Coupled with GC-MS

“…These sesquiterpenic compounds can be related with the floral characteristics of wines and derives from farnesyl diphosphate, an intermediate in isoprenoid and ergosterol biosynthesis at acidic pH, the instability of the diphosphate group leads to the release of Farnesol and its isomer Nerolidol [20]. They were identified in different wine varieties and in the Italian white wines Grillo, Inzolia and Cataratto [1,10,16].…”

Review of Aroma Formation through Metabolic Pathways of Saccharomyces cerevisiae in Beverage Fermentations

“…Differences in secondary metabolite composition are observed when industrial strains are used in fermentation, suggesting that genetic differences between lab and industrial strains account for the differences in secondary metabolite production (Howell et al 2005, Rossouw et al 2008, Richter et al 2013. Most transcriptomic studies that have analyzed the impact of environmental changes on yeast fermentation of wines were limited by the use of only a small number of industrially relevant strains (Rossouw et al 2008, Steyer et al 2012, García-Ríos et al 2014). Thus, a broader assessment of commercially relevant S. cerevisiae strains is required to fully elucidate the regulation of flavor compounds produced during fermentation.…”