The chromosomal evolutionary lineage of the genus Zygosaccharomyces

Genome ploidy of Zygosaccharomyces rouxii is an intriguing topic in the field of industrial yeast research. However, the evolutionary relationship between the genome of Z. rouxii and other Zygosaccharomyces species is complex and not completely understood. In this study, we determined the genome sequences of Z. rouxii NCYC 3042, also referred to as ‘Z. pseudorouxii,’ and Z. mellis CBS 736(T). We also conducted comparative analysis of the yeast genomes of a total of 21 strains, including 17 strains of nine Zygosaccharomyces species. This comparative genomics revealed that 17 Zygosaccharomyces strains are classified into four groups consisting of nine genome types: (i) Z. rouxii, Z. mellis, Z. sapae, Z. siamensis, and ‘Candida versatilis’ t-1 belong to the group Rouxii sharing four related genome types (Rouxii-1 to Rouxii-4), (ii) Z. bailii, Z. parabailii, and Z. pseudobailii belong to the group Bailii sharing three related genome types (Bailii-1 to Bailii-3), (iii and iv) Z. bisporus and Z. kombuchaensis belong to the groups Bisporus and Kombuchaensis, respectively, which each have haploid genomes. The Zygosaccharomyces genome seems to have acquired complexity and diversity through evolutionary events such as interspecies hybridization, reciprocal translocation, and diploidization of these nine genome types.