Format: ORAL

Yile Huang1,2, Terezie Mandkov1,3, Nicolas Blavet1, Manuel Poretti4, Xinyi Guo1, Milan Pouch1,2, Rimjhim Roy Choudhury4, Manuel B. Crespo5, Christian Parisod4 and Martin A. Lysak1,2

1 CEITEC – Central European Institute of Technology, Masaryk University, Brno, Czech Republic 2 National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic 3 Institute of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic 4 Department of Biology, University of Fribourg, Fribourg, Switzerland 5 Departamento de Ciencias Ambientales y Recursos Naturales, Universidad de Alicante, Alicante, Spain

In plants, whole-genome duplications (WGDs) are often followed by genome-wide diploidization including descending dysploidy, i.e. chromosomal rearrangements that reduce chromosome number and genome size. However, the genomic basis and evolutionary significance of chromosomal rearrangements are still poorly understood. Here, we report the consequences of the WGD event for infrageneric diversification using comparative genomic analyzes of eight de novo assembled Biscutella species (Buckler mustard) that differ in genome size (0.7 to 1.1 Gbp) and chromosome number (n=6, 8 or 9). The estimated 9 million-year rediploidization of the progenitor genome was marked by extensive reorganization of the parental subgenomes, genome downsizing, descending dysploidy (n=14 n=6, 8 or 9), and cladogenetic/speciation events in the genus Biscutella. We reconstructed the ancestral genome of Biscutella and analyzed two differently fractionated subgenomes, which have evolved at unequal rates during post-polyploid diploidization of the sequenced genomes. Although the dominant, less fractionated subgenome has retained more intact genes, the more fractionated subgenome has a more stable karyotype structure with fewer chromosomal breakpoints. In addition, duplicated syntenic genes and their extensive structural variation are associated with environmental adaptation. Our results provide new insights into the role of dysploid changes in plant genome evolution and speciation. This work was supported by a grant from the Czech Science Foundation (21-07748L).