Publication details
Structure and evolution of the meso-octoploid genome of Heliophila variabilis (Brassicaceae)
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| Year of publication | 2022 |
| Type | Conference abstract |
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| Description | There is broad consensus that whole genome duplications (WGDs) followed by post-polyploid diploidization (PPD) have contributed significantly to the evolution of land plants and, in particular, angiosperms. The Heliophileae, the most morphologically diverse lineage in the mustard family, remains largely unknown with respect to its genome origin, evolution, and phylogenetic relationships. Here, we report the chromosome-scale assembly of a first meso-octoploid crucifer genome, the meso-octoploid Heliophila variabilis (~300 Mb, 2n=22). Although the H. variabilis genome has shrunk considerably and the octoploid chromosome number was reduced, most of the homoeologous chromosomal regions have been identified in four copies, accompanied by biased divergence in gene density and phylogenetic relationships. These four genomic copies were identified as two less fractionated (sub1 and sub2) and two more fractionated (sub3 and sub4) subgenomes. The putative ancestral genomes diverged during Oligocene-Miocene and their subsequent mergers may have occurred rapidly c. 18 million years ago. The biased subgenome fractionation was associated with extensive chromosomal rearrangements that mediated chromosome fusions and the activity of transposable elements. The progressive genome diploidization has enabled evolution of many important traits, including drought tolerance, disease resistance, leaf development, and flower color evolution. Our results provide a deeper understanding of the mid- and long-term evolutionary consequences of polyploidization and post-polyploid diploidization cycles. This work was supported by the Czech Science Foundation (project no. 19-07487S). |