Publication details
Weird and wonderful – an origin of sex chromosomes in two races of Rumex hastatulus
| Authors | |
|---|---|
| Year of publication | 2023 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Rumex hastatulus is a dioecious plant that evolved into two distinct races with a polymorphic sex chromosome system, XY in Texas (Tx) race and XYY in North Carolina (NC). The time of sex chromosome divergence in the older race (Tx) is estimated to be 9–16 mya, while the younger system (NC) evolved only 0.6 mya. Male plants of Tx race (2n = 10) possess telocentric X chromosome and large metacentric Y chromosome. In contrast to Tx race, NC males (2n = 9) underwent a series of chromosomal rearrangements that led to substantial changes in their genome organization. However, the exact mechanism through which was NC race genome formed and which parts of the autosomes were lost has not been completely understood yet. Using the combination of NGS data and PacBIO technology, we analysed the repeatome of both races and identified sex-specific satellite candidates for further cytogenetic analysis. The difference in the proportion of the sex-specific satellites and their position revealed that the neo-sex chromosome system of NC underwent at least two fusions between the sex chromosomes and one pair of autosomes. These rearrangements were further accompanied by multiple breakages of the ancestral Y chromosome that led to the formation of two neo-Y chromosomes (Y1, Y2) in NC males. NC race genome was further shaped by additional inversion and fusion supported by the localization of satellites on the autosomes. The exact understanding of the chromosomal rearrangements that formed the genome of Rumex hastatulus will allow us to study the epigenetic degeneration of neo-Y chromosomes. Further, this system is an ideal model to study dosage compensation evolution in old and new sex chromosome systems with the same evolutionary background and to discover the early mechanisms of sex chromosome evolution. |