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Genome evolution following whole genome duplication events in the Biscutella laevigata (Brassicacea) species complex

Author Marc BERINGER
Director of thesis Prof. Dr. Christian Parisod
Co-director of thesis
Summary of thesis

Whole genome duplication (WGD) events are common in plants. After a WGD, the genome undergoes reorganization and degradation.

This reorganization process is thought to follow the gene balance hypothesis, which states that important gene duplicates and their interactors will be retained in the new polyploid, while other duplicates are gradually lost again. Gene duplicates that convey an adaptive advantage, seem to be retained more likely than genes not subject to strong purifying selection. However, there also seem to be loci of neutral effect on the plants fitness that are retained in the polyploid, due to strong linkage to favorable loci.

The Biscutella laevigata species complex offers diploid species that share the ancient WGD event with all other Brassicacea (approximately 8 MYA) and autotetraploid subspecies, which have undergone a more recent (approximately 1.2MYA) WGD event. Its relatively close relationship to Arabidopsis thaliana and its ecological distribution, which hints towards WGDs mediating adaptive advantages, makes this species complex an ideal model to investigate the evolution of a plant genome following an ancient and a more recent WGD event.

Using whole genome sequencing and transcriptome data coupled with ecological data, we will investigate the detailed nature of how the genome reorganizes after WGD events, as well as determine the transcriptional plasticity of diploid and polyploid genomes in different environments.

Possibly this will enable us to draw generalities of how WGDs affect plant adaptation.

Status finishing
Administrative delay for the defence 2022