Fig. 7: Hypothetical model for the origin of holocentricity in woodrushes.

After several fusions of whole atypical monocentric chromosomes ( Juncus-like type), centromeric domains were initially conserved in the larger chromosomes (hypothetical intermediate state), forming polycentric chromosomes. Subsequently, expansion of the centromeric ___domain and genome rearrangement gave rise to the holocentric condition. Later colonization of Lusy-type satellites allowed the maintenance of functional centromeres. M monocentric, H holocentric. Divergence time was obtained from the Timetree of Life (https://timetree.org/).