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Gene expression is an essential step in the translation of genotypes into phenotypes. However, little is known about the transcriptome architecture and the underlying genetic effects at the species level. Here we generated and analyzed the pan-transcriptome of ~1,000 yeast natural isolates across 4,977 core and 1,468 accessory genes. We found that the accessory genome is an underappreciated driver of transcriptome divergence. Global gene expression patterns combined with population structure showed that variation in heritable expression mainly lies within subpopulation-specific signatures, for which accessory genes are overrepresented. Genome-wide association analyses consistently highlighted that accessory genes are associated with proportionally more variants with larger effect sizes, illustrating the critical role of the accessory genome on the transcriptional landscape within and between populations. Insight from the transcriptomes of 1,032 Saccharomyces cerevisiae natural isolates emphasizes the essential contribution of accessory genes to the species-level transcriptional landscape.

Genomic architecture changes can significantly influence genome evolution and phenotypic variation within a species. Polyploidization events are thought to be one of the important catalysts for adaptation, speciation and tumorigenesis. However, little is known about the overall impact of such events on the phenotypic landscape at a population level. Here, we completely sequenced and phenotyped a large population of 1060 Brettanomyces bruxellensis yeast isolates, punctuated by multiple independent polyploidization events, notably allopolyploidization, giving rise to a highly structured population related to various anthropized ecological niches. A subgenome-aware population analysis revealed differential genome evolution between the primary and acquired genomes, with the latter showing a higher degree of conservation between isolates. Distinct phenotypic signatures were identified across major populations, with allopolyploid isolates showing an enrichment of extreme phenotypes. Genome-wide association analysis consistently revealed the substantial influence of the acquired genome of allopolyploids, with associated variants exhibiting significantly larger effect sizes than those from the primary genome. Overall, our study illustrates the profound and species-wide impact of polyploidization events on genome evolution and phenotypic diversity. It also provides a useful resource to explore the impact of allopolyploidy on adaptation. The authors sequence and phenotype over 1,000 isolates of the yeast Brettanomyces bruxellensis , and show how allopolyploidization reshapes genome evolution and enhances phenotypic diversity, highlighting the role of acquired subgenomes.

With the rise of high-throughput sequencing technologies, a holistic view of genetic variation within populations—through population genomics studies—appears feasible, although it remains an ongoing effort. Genetic variation arises from a diverse range of evolutionary forces, with mutation and recombination being key drivers in shaping genomes. Studying genetic variation within a population represents a crucial first step in understanding the relationship between genotype and phenotype and the evolutionary history of species. In this context, the budding yeast Saccharomyces cerevisiae has been at the forefront of population genomic studies. In addition, it has a complex history that involves adaptation to a wide range of wild and human-related ecological niches. Although to date more than 3,000 diverse isolates have been sequenced, there is currently a lack of a resource bringing together sequencing data and associated metadata for all sequenced isolates. To perform a comprehensive analysis of the population structure of S. cerevisiae, we collected genome sequencing data from 3,034 natural isolates and processed the data uniformly. We determined ploidy levels, identified single nucleotide polymorphisms (SNPs), small insertion–deletions (InDels), copy number variations (CNVs), and aneuploidies across the population, creating a publicly accessible resource for the yeast research community. Interestingly, we showed that this population captures ∼93% of the species diversity. Using neighbor-joining and Bayesian methods, we redefined the populations, revealing clustering patterns primarily based on ecological origin. This work represents a valuable resource for the community and efforts have been made to make it evolvable and integrable to future yeast population studies.

RNA modifications are involved in numerous biological processes and are present in all RNA classes. These modifications can be constitutive or modulated in response to adaptive processes. RNA modifications play multiple functions since they can impact RNA base-pairings, recognition by proteins, decoding, as well as RNA structure and stability. However, their roles in stress, environmental adaptation and during infections caused by pathogenic bacteria have just started to be appreciated. With the development of modern technologies in mass spectrometry and deep sequencing, recent examples of modifications regulating host-pathogen interactions have been demonstrated. They show how RNA modifications can regulate immune responses, antibiotic resistance, expression of virulence genes, and bacterial persistence. Here, we illustrate some of these findings, and highlight the strategies used to characterize RNA modifications, and their potential for new therapeutic applications.

Gene expression is an essential step in the translation of genotypes into phenotypes. However, little is known about the transcriptome architecture and the underlying genetic effects at a species-level. Here, we generated and analyzed the pan-transcriptome of ∼1,000 yeast natural isolates across 4,977 core and 1,468 accessory genes. We found that the accessory genome is an underappreciated driver of the transcriptome divergence. Global gene expression patterns combined with population structure show that the heritable expression variation mainly lies within subpopulation-specific signatures, for which the accessory genes are overrepresented. Genome-wide association analyses consistently highlight that the accessory genes are associated with proportionally more variants with larger effect sizes, illustrating the critical role of the accessory genome on the transcriptional landscape within and between populations.

The emergence of graph pangenomes has significantly advanced the study of structural variants (SVs) across diverse species. However, the impact of complex polyploidization events, particularly allopolyploidy, on SV landscapes remains poorly explored. Brettanomyces bruxellensis, a yeast species shaped by multiple allopolyploidization events, offers a compelling model due to its well-characterized genomic and phenotypic diversity. Here, we integrated subgenome-resolved assemblies with population-scale genomic and transcriptomic datasets to characterize SVs distribution and their functional impact at the species level. Leveraging a constructed reference graph pangenome, we identified sequences that are unique to each subgenome, and detected 212,177 SVs across 1,060 sequenced isolates. Allopolyploid genomes harbored significantly more SVs (320 on average) than diploid genomes (116 on average), reflecting the extensive impact of hybridization on the genome architecture. A subset of SVs originating from ancestral divergence between subgenomes (hybridization-associated SVs) formed distinct hotspots of structural diversity. Furthermore, functional association analysis revealed that 27.5% of SVs exert local regulatory effects on gene expression. Interestingly, hybridization-associated structural variants disproportionately affect gene expression, with a greater proportion of associated variants and a significantly larger effect size compared to other SVs. Overall, these findings underscore the role of allopolyploidization in driving both structural and functional genomic diversification. Our study also highlights the value of graph-based approaches in dissecting complex genome evolution.

With the rise of high-throughput sequencing technologies, a holistic view of genetic variation within populations – through population genomics studies – appears feasible, although it remains an ongoing effort. Genetic variation arises from a diverse range of evolutionary forces, with mutation and recombination being key drivers in shaping genomes. Studying genetic variation within a population represents a crucial first step in understanding the relationship between genotype and phenotype and the evolutionary history of species. In this context, the budding yeast Saccharomyces cerevisiae has been at the forefront of population genomic studies. In addition, it has a complex history that involves adaptation to a wide range of wild and human-related ecological niches. Although to date more than three thousand diverse isolates have been sequenced, there is currently a lack of a resource bringing together sequencing data and associated metadata for all sequenced isolates. To perform a comprehensive analysis of the population structure of S. cerevisiae, we collected genome sequencing data from 3,034 natural isolates and processed the data uniformly. We determined ploidy levels, identified single nucleotide polymorphisms (SNPs), small insertion-deletions (InDels), copy number variations (CNVs), and aneuploidies across the population, creating a publicly accessible resource for the yeast research community. Interestingly, we showed that this population captures ∼93% of the species diversity. Using neighbor-joining and Bayesian methods, we redefined the populations, revealing clustering patterns primarily based on ecological origin. This work represents a valuable resource for the community and efforts have been made to make it evolvable and integrable to future yeast population studies.