The Interspecific Fungal Hybrid Verticillium longisporum Displays Subgenome-Specific Gene Expression

Hybridization is an important evolutionary mechanism that can enable organisms to adapt to environmental challenges. It has previously been shown that the fungal allodiploid species Verticillium longisporum, the causal agent of verticillium stem striping in rapeseed, originated from at least three independent hybridization events between two haploid species. To reveal the impact of genome duplication as a consequence of hybridization, we studied the genome and transcriptome dynamics upon two independent V. longisporum hybridization events, represented by the hybrid lineages "A1/D1" and "A1/D3." We show that genomes are characterized by extensive chromosomal rearrangements, including between parental chromosomal sets. hybrids display signs of evolutionary dynamics that are typically associated with the aftermath of allodiploidization, such as haploidization and more relaxed gene evolution. The expression patterns of the two subgenomes within the two hybrid lineages are more similar than those of the shared A1 parent between the two lineages, showing that the expression patterns of the parental genomes homogenized within a lineage. However, as genes that display differential parental expression do not typically display the same pattern , we conclude that subgenome-specific responses occur in both lineages. Overall, our study uncovers genomic and transcriptomic plasticity during the evolution of the filamentous fungal hybrid and illustrates its adaptive potential. is a genus of plant-associated fungi that includes a few plant pathogens that collectively affect a wide range of hosts. On several occasions, haploid species hybridized into the stable allodiploid species , which is, in contrast to haploid species, a Brassicaceae specialist. Here, we studied the evolutionary genome and transcriptome dynamics of and the impact of the hybridization. genomes display a mosaic structure due to genomic rearrangements between the parental chromosome sets. Similar to other allopolyploid hybrids, displays an ongoing loss of heterozygosity and more relaxed gene evolution. Also, differential parental gene expression is observed, with enrichment for genes that encode secreted proteins. Intriguingly, the majority of these genes display subgenome-specific responses under differential growth conditions. In conclusion, hybridization has incited the genomic and transcriptomic plasticity that enables adaptation to environmental changes in a parental allele-specific fashion.