Evolutionary innovations and genetic diversity in angiosperm centromeres

Area of Science:

• Genomics
• Evolutionary Biology
• Molecular Biology

Background:

• Centromeres are crucial for chromosome segregation but exhibit rapid sequence evolution, posing a paradox in genome evolution.
• Understanding centromere evolution is key to deciphering genome dynamics and speciation mechanisms.

Purpose of the Study:

• To investigate the evolutionary dynamics of centromeres in angiosperms.
• To identify the molecular mechanisms driving centromere sequence turnover and functional conservation.
• To establish a framework for centromere-driven speciation.

Main Methods:

• Integrated analysis of over 400 resolved centromeres from 17 diploid angiosperms.
• Utilized 1,000+ pan-genomic assemblies, resequencing data, and congeneric whole-genome sequences.
• Employed population-level and temporal reconstruction analyses across species.

Main Results:

• Angiosperm centromere organization is shaped by lineage-specific combinations of satellite repeats and transposable elements (TEs).
• TE insertion patterns are key drivers of centromere structural diversification and positional shifts.
• Centromere sequences show plasticity within species, with satellite repeats as hotspots of evolution, leading to species-specific heterogeneity.
• Emergence and differentiation of centromeric repeats occur during speciation, often linked to karyotype reorganization.

Conclusions:

• Centromere innovation results from an interplay between genome evolution, chromosomal shuffling, and selection.
• The study proposes a unifying framework linking centromere evolution to speciation.
• Phylogenomic signatures reveal centromere-driven speciation as a significant evolutionary process.