The sustainable future of food industry and consumer demands meet the need to generate out-performing new yeast variants. This is addressed by using the natural yeast diversity and breeding via sexual reproduction but the recovery of recombined spores in many industrial strains is limited. To circumvent this drawback, we examined whether or not the process of meiotic Return to Growth (RTG) that allows S. cerevisiae diploid cells to initiate meiotic recombination genome-wide and then re-enter into mitosis, will be effective to generate recombinants in a sterile and polyploid baking yeast strain (CNCM). We proceeded in four steps. First, whole genome sequencing of the CNCM strain revealed that it was an unbalanced polymorphic triploid. Second, we annotated a panel of genes likely involved in the success of the RTG process. Third, we examined the strain progression into sporulation and fourth, we developed an elutriation and reiterative RTG protocol that allowed to generate extensive libraries of recombinant RTGs, enriched up to 70 %. Altogether, the genome analysis of 122 RTG cells demonstrated that they were bona fide RTG recombinants since the vast majority retained the parental ploidy and exhibited allelic variations involving 1–60 recombined regions per cell with a length of ∼0.4–400 kb. Thus, beyond diploid laboratory strains, we demonstrated the proficiency of this natural non-GM and marker-free process to recombine a sterile and polyploid hybrid yeast, thus providing an unprecedented resource to screen improved traits.

食品工业的可持续未来和消费者需求满足了产生性能优异的新酵母变种的需求。这是通过使用天然酵母多样性和通过有性繁殖进行育种来解决的，但在许多工业菌株中重组孢子的恢复是有限的。为了规避这个缺点，我们检查了减数分裂恢复生长 (RTG) 的过程是否允许酿酒酵母二倍体细胞在全基因组范围内启动减数分裂重组，然后重新进入有丝分裂，将有效地在不育和多倍体烘焙酵母菌株 (CNCM) 中产生重组体。我们分四步进行。首先，CNCM 菌株的全基因组测序显示它是一个不平衡的多态性三倍体。其次，我们注释了一组可能参与 RTG 过程成功的基因。第三，我们检查了菌株进入孢子形成的过程，第四，我们开发了一种淘洗和重复 RTG 协议，允许生成大量重组 RTG 文库，富集率高达 70%。总之，对 122 个 RTG 细胞的基因组分析表明它们是真正的RTG 重组体大部分保留了亲本倍性，并表现出等位基因变异，涉及每个细胞 1-60 个重组区域，长度约为 0.4-400 kb。因此，除了二倍体实验室菌株之外，我们展示了这种天然非转基因和无标记过程重组不育和多倍体杂交酵母的能力，从而为筛选改良性状提供了前所未有的资源。