The evolutionary aftermath of fungal hybridization

Genome hybridization, i.e. the combination of two often divergent parental genomes, is widely observed within eukaryotic taxa such as plants, animals and fungi. In particular, interspecies hybridization of genomes from two distinct parents induces major genomic and transcriptomic alterations, the so-called genome shock. For example, many hybrids experience rapid loss of heterozygosity and gene loss, two processes that are thought to stabilize the newly formed chimeric genome. Similarly, the transcriptional regulation of the hybrid needs to cope with two divergent regulatory circuits that can exhibit considerable cross-talk. Nevertheless, many hybrids display enhanced fitness compared to their parents. For example, hybrid crops often have higher yield and enhanced resistance against abiotic and biotic stresses compared to their parents. Similarly, fungal hybrids often display enhanced fitness, allowing them to exploit novel or challenging niches. Yet the molecular basis for these adaptations and its link to genomic and transcriptomic alterations remain largely unknown. We study the evolutionary aftermaths of very recent genome hybridizations, focusing on plant pathogenic and food-spoilage fungi. To this end, we study the genomes and transcriptomes of hybrids and their parents using next-generation sequencing technologies. In particular, we use the long-read sequencing capacity of the PacBio platform to disentangle the two sub-genomes in hybrids. By comparing hybrids and their parents we are searching for the precise alterations in the hybrid genomes and transcriptomes, and look for molecular mechanisms that influence hybrid genome stability and enhanced fitness.