Format: ORAL

Terezie Mandkov1, Judita Zozomov-Lihov2, Hiroshi Kudoh3, Yunpeng Zhao4, Martin A. Lysak1, and Karol Marhold2,5

1 Central European Institute of Technology, and Faculty of Science, Masaryk University, Brno, Czech Republic, 2 Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Bratislava, Slovak Republic, 3 Center for Ecological Research, Kyoto University, Otsu, Japan, 4 The Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, College of Life Sciences, Zhejiang University, Hangzhou, China; Laboratory of Systematic and Evolutionary Botany and Biodiversity, Institute of Ecology and Conservation Centre for Gene Resources of Endangered Wildlife, Zhejiang University, Hangzhou, China, 5 Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic

The genus Cardamine (Brassicaceae), encompassing over 200 species, exhibits a global distribution except of Antarctica. C. occulta, an octoploid (2n=64) weed indigenous to Eastern Asia, has become invasive after introductions to various continents, including Europe. In Europe this species first appeared in the Mediterranean region, particularly in Spain and in Italy (here due to rice cultivation near Torino). C. occulta shares its Eastern Asian habitat with related species such as the tetraploid (2n=32) C. kokaiensis and C. scutata, as well as the octoploid (2n=64) C. dentipetala. Genomic in situ hybridization and large-scale comparative chromosome painting were employed to elucidate the parental genomes and chromosome composition of these Cardamine species. All species trace their lineage to a common ancestral Cardamine genome (n=8), structurally resembling the Ancestral Crucifer Karyotype (n = 8) but differentiated by a translocation between chromosomes AK6 and AK8. The allotetraploid C. scutata resulted from hybridization between the diploids C. parviflora and C. amara. Conversely, C. kokaiensis has an autotetraploid origin related to C. parviflora. Notably, the octoploid C. occulta likely originated through hybridization between the tetraploids C. scutata and C. kokaiensis. The octoploid genome of C. dentipetala probably originated from C. scutata via autopolyploidization. Apart from a five species-specific centromere repositionings and one pericentric inversion post-dating polyploidization events, parental subgenomes remained stable in Asian tetra- and octoploids. Post-polyploid evolution in Asian Cardamine polyploids did not involve descending dysploidy or intergenomic rearrangements. The combination of diverse parental (sub)genomes adapted to distinct habitats conferred an evolutionary advantage to newly formed polyploids, allowing them to occupy new ecological niches. The revealed genomic insights into Cardamine polyploids not only enhance our understanding of their evolutionary history but also provide valuable knowledge for the targeted management of invasive species.