Evolutionary dynamics of the pan-centromere architecture in oaks
Centromeres ensure faithful chromosome segregation and genome stability, yet their DNA evolves rapidly, presenting a long-standing centromere paradox. Here we characterise the genomic and epigenomic architecture of >1,300 candidate centromeres from 111 high-quality Quercus (oak) genomes. We show that lineage-specific expansion of QuCEN146 satellite drives centromere turnover in oaks by displacing…
Centromeres are essential for accurate chromosome separation and genome stability, but their DNA exhibits rapid evolution, creating a persistent centromere paradox. In this study, researchers examined the genomic and epigenomic architecture of 1,300 potential centromeres from 111 high-quality Quercus (oak) genomes. They discovered that lineage-specific expansion of QuCEN146 satellite DNA drives centromere turnover in oaks by pushing ancestral LTR-rich sequences to the surrounding areas. Genetic drift then aids the fixation of these satellite-rich centromeres.
In Q. serrata, population-scale studies show significant variation in satellite-rich centromeres, resulting from array expansion and contraction, strand-orientation shifts, and interspecific introgression. In contrast, Q. variabilis possesses LTR-rich centromeres with minimal polymorphism and high collinearity across populations. This stability is maintained through suppressed local recombination, linked selection, and limited LTR dynamics.
Moreover, the study uncovers chromosome-independent evolutionary patterns for both satellite-rich and LTR-rich centromeres. Overall, these findings reveal how various evolutionary processes contribute to centromere turnover and create distinct centromeric sequence landscapes in forest trees.
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