Hall SE, Luo S, Hall AE, Preuss D. Differential rates of local and global homogenization in centromere satellites from Arabidopsis relatives.
Genetics 2005;
170:1913-27. [PMID:
15937135 PMCID:
PMC1449784 DOI:
10.1534/genetics.104.038208]
[Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Higher eukaryotic centromeres contain thousands of satellite repeats organized into tandem arrays. As species diverge, new satellite variants are homogenized within and between chromosomes, yet the processes by which particular sequences are dispersed are poorly understood. Here, we isolated and analyzed centromere satellites in plants separated from Arabidopsis thaliana by 5-20 million years, uncovering more rapid satellite divergence compared to primate alpha-satellite repeats. We also found that satellites derived from the same genomic locus were more similar to each other than satellites derived from disparate genomic regions, indicating that new sequence alterations were homogenized more efficiently at a local, rather than global, level. Nonetheless, the presence of higher-order satellite arrays, similar to those identified in human centromeres, indicated limits to local homogenization and suggested that sequence polymorphisms may play important functional roles. In two species, we defined more extensive polymorphisms, identifying physically separated and highly distinct satellite types. Taken together, these data show that there is a balance between plant satellite homogenization and the persistence of satellite variants. This balance could ultimately generate sufficient sequence divergence to cause mating incompatibilities between plant species, while maintaining adequate conservation within a species for centromere activity.
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