Department of Genetics, Physiology and Microbiology. Unit of Microbiology. Biology Faculty, Complutense University of Madrid, Madrid, 28040, Spain.
Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, 2829-516, Portugal.
Environ Microbiol. 2021 Jun;23(6):3182-3195. doi: 10.1111/1462-2920.15540. Epub 2021 May 11.
The adaptation to the different biotic and abiotic factors of wine fermentation has led to the accumulation of numerous genomic hallmarks in Saccharomyces cerevisiae wine strains. IRC7, a gene encoding a cysteine-S-β-lyase enzyme related volatile thiols production in wines, has two alleles: a full-length allele (IRC7 ) and a mutated one (IRC7 ), harbouring a 38 bp-deletion. Interestingly, IRC7 -encoding a less active enzyme - appears widespread amongst wine populations. Studying the global distribution of the IRC7 allele in different yeast lineages, we confirmed its high prevalence in the Wine clade and demonstrated a minority presence in other domesticated clades (Wine-PDM, Beer and Bread) while it is completely missing in wild clades. Here, we show that IRC7 -homozygous (HS) strains exhibited both fitness and competitive advantages compared with IRC7 -homozygous (HF) strains. There are some pieces of evidence of the direct contribution of the IRC7 allele to the outstanding behaviour of HS strains (i.e., improved response to oxidative stress conditions and higher tolerance to high copper levels); however, we also identified a set of sequence variants with significant co-occurrence patterns with the IRC7 allele, which can be co-contributing to the fitness and competitive advantages of HS strains in wine fermentations.
葡萄酒发酵对不同生物和非生物因素的适应导致了酿酒酵母中积累了许多基因组特征。IRC7 是一种编码与葡萄酒中挥发性硫醇产生有关的半胱氨酸 S-β-裂合酶的基因，有两个等位基因：全长等位基因（IRC7）和突变等位基因（IRC7），后者含有 38bp 的缺失。有趣的是，IRC7 编码的酶活性较低，但在葡萄酒种群中广泛存在。通过研究 IRC7 等位基因在不同酵母谱系中的全球分布，我们证实了它在 Wine 分支中的高流行率，并证明了它在其他驯化分支（Wine-PDM、Beer 和 Bread）中的少数存在，而在野生分支中则完全缺失。在这里，我们表明 IRC7 纯合（HS）菌株与 IRC7 纯合（HF）菌株相比具有更强的适应性和竞争力。有一些证据表明 IRC7 等位基因直接有助于 HS 菌株的出色表现（即，对氧化应激条件的反应更好，对高铜水平的耐受性更高）；然而，我们还确定了一组与 IRC7 等位基因具有显著共现模式的序列变体，这些变体可能共同有助于 HS 菌株在葡萄酒发酵中的适应性和竞争力。
