Shattered but Alive – Surviving Mitotic Catastrophe during Genome Elimination

Safeguarding the genome from instability is essential for maintaining the health and fitness of an organism. On the other hand, alterations to genomes provide an avenue for organisms to adapt to change. Small, gradual changes to DNA sequences have been well studied but more drastic alterations such as those derived from chromothripsis, the phenomenon in which a chromosome is shattered and reassembled incorrectly in a single step, are not well understood. We recently reported the occurrence of chromothripsis during genome elimination in Arabidopsis thaliana. We show that micronuclei are likely involved, providing a crucial mechanistic link between chromothripsis in plant and animal systems. In addition, we provide genetic evidence for the role of non-homologous end joining in repairing DNA breaks from shattered chromosomes. Using our system in Arabidopsis, the karyotypic novelty that results can also be passed on to the offspring. This enables the study of the molecular mechanisms of chromothripsis as well as its consequences across multiple generations in an organismal setting.