The mutational dynamics of the Arabidopsis centromeres.

Kilobase-sized indels and point mutations drive centromere evolution in Arabidopsis thaliana, with point mutations occurring nearly ten times faster than elsewhere in the genome.

• Why it matters: Understanding the mutational processes shaping centromeres is crucial because they ensure accurate chromosome segregation, yet their evolutionary dynamics remain poorly characterized.
• What they did: Using replicated genome assemblies of mutation accumulation lines, researchers characterized the mutation spectrum, revealing frequent indels that preserve tandem repeats and elevated point mutation rates driven by homology-directed DNA repair.
• The result: Simulations indicate that these mutations alone can produce the large, homogenized repeat blocks seen in natural centromeres, advancing our understanding of centromere architecture and evolution.