Proportional abundance (%) of commercial and commercial-related MLGs in late-stage fermentations from the winery and OG vineyard.

Proportional abundance (%) of commercial and commercial-related MLGs in late-stage fermentations from the winery and OG vineyard.</p

Venn diagrams of MLG distribution by vintage and location.

Red numbers, commercial MLGs; blue numbers, commercial related MLGs; black numbers, unique MLGs. a) Venn diagram of strain distribution by vintage. b) Venn diagram of MLG distribution between vineyard and winery locations. Venn diagrams adjacent to the main diagram display the MLG distribution for each location by vintage.</p

Phylogenetic network of database commercial yeast and unique vineyard/winery MLGs.

<p>An unrooted phylogenetic network computed from a Bruvo Distance matrix using the Neighbor-Net method [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0160259#pone.0160259.ref059" target="_blank">59</a>] and drawn to scale. Unique strains are labelled “SBV” followed by a unique number. Commercial strains are in red. Isolates with > 80% membership in one of three unique subpopulations (K6-K8) are colored by cluster as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0160259#pone.0160259.g004" target="_blank">Fig 4</a>.</p

Map of relative vineyard and winery locations.

<p>The vineyard blocks and distances are drawn to scale.</p

Impact of Commercial Strain Use on <i>Saccharomyces cerevisiae</i> Population Structure and Dynamics in Pinot Noir Vineyards and Spontaneous Fermentations of a Canadian Winery

<div><p>Wine is produced by one of two methods: inoculated fermentation, where a commercially-produced, single <i>Saccharomyces cerevisiae</i> (<i>S</i>. <i>cerevisiae</i>) yeast strain is used; or the traditional spontaneous fermentation, where yeast present on grape and winery surfaces carry out the fermentative process. Spontaneous fermentations are characterized by a diverse succession of yeast, ending with one or multiple strains of <i>S</i>. <i>cerevisiae</i> dominating the fermentation. In wineries using both fermentation methods, commercial strains may dominate spontaneous fermentations. We elucidate the impact of the winery environment and commercial strain use on <i>S</i>. <i>cerevisiae</i> population structure in spontaneous fermentations over two vintages by comparing <i>S</i>. <i>cerevisiae</i> populations in aseptically fermented grapes from a Canadian Pinot Noir vineyard to <i>S</i>. <i>cerevisiae</i> populations in winery-conducted fermentations of grapes from the same vineyard. We also characterize the vineyard-associated <i>S</i>. <i>cerevisiae</i> populations in two other geographically separate Pinot Noir vineyards farmed by the same winery. Winery fermentations were not dominated by commercial strains, but by a diverse number of strains with genotypes similar to commercial strains, suggesting that a population of <i>S</i>. <i>cerevisiae</i> derived from commercial strains is resident in the winery. Commercial and commercial-related yeast were also identified in the three vineyards examined, although at a lower frequency. There is low genetic differentiation and <i>S</i>. <i>cerevisiae</i> population structure between vineyards and between the vineyard and winery that persisted over both vintages, indicating commercial yeast are a driver of <i>S</i>. <i>cerevisiae</i> population structure. We also have evidence of distinct and persistent populations of winery and vineyard-associated <i>S</i>. <i>cerevisiae</i> populations unrelated to commercial strains. This study is the first to characterize <i>S</i>. <i>cerevisiae</i> populations in Canadian vineyards.</p></div

Pairwise F_ST values for <i>S</i>. <i>cerevisiae</i> populations from different locations, with and without commercial and commercial-related genotypes.

<p>Pairwise F_ST values for <i>S</i>. <i>cerevisiae</i> populations from different locations, with and without commercial and commercial-related genotypes.</p

Pairwise fixation index (F_ST) values for <i>S</i>. <i>cerevisiae</i> populations at different stages of fermentation.

<p>Pairwise fixation index (F_ST) values for <i>S</i>. <i>cerevisiae</i> populations at different stages of fermentation.</p

DISTRUCT plots of inferred ancestry profiles from vineyard and winery <i>S</i>. <i>cerevisiae</i> populations.

<p>Each column represents an ancestry profile for an individual MLG. Each colour corresponds to a subpopulation/cluster. The scale of each colour in an ancestry profile represents the proportion (membership coefficient) of the individual’s ancestry profile assigned to that cluster, as measured on the y-axis of each plot. The legend indicates the subpopulation/cluster number and colour. An ancestry profile for each commercial and commercial-related MLG in the dataset is noted in the legend. Subpopulations containing commercial MLGs with membership coefficients >80% are labelled with the strain name in parentheses, unique subpopulations with SBV in parentheses.</p

Microsatellite loci used in this study, selected from Richards et al. 2009.

<p>Microsatellite loci used in this study, selected from Richards et al. 2009.</p

Chi-square test of independence between OG vineyard/winery and type of <i>S</i>. <i>cerevisiae</i> MLG.

<p>Chi-square test of independence between OG vineyard/winery and type of <i>S</i>. <i>cerevisiae</i> MLG.</p