spp. chromosomes are very small and accumulate a variety of repetitive DNA families around the centromeres. However, the proximal regions of chromosomes remain poorly understood, especially regarding the nature and organisation of the sequences. Taking advantage of the genome sequences of . (2 = 44), . , and . (. progenitors with 2 = 22) and good coverage genome sequencing of dozens of other wild spp., repetitive DNA sequences were identified, and the genomes were compared to decipher particularities of pericentromeric structures. The searches revealed a short tandem repeat (82 bp length) typical of Gypsy/TAT LTR retrotransposons, named Coffea_sat11. This repeat organises clusters with fragments of other transposable elements, comprising regions of non-coding RNA production. Cytogenomic analyses showed that Coffea_sat11 extends from the pericentromeres towards the middle of the chromosomal arms. This arrangement was observed in the allotetraploid . chromosomes, as well as in its progenitors. This study improves our understanding of the role of the Gypsy/TAT LTR retrotransposon lineage in the organisation of pericentromeres, as well as the conservation of Coffea_sat11 within the genus. The relationships between fragments of other transposable elements and the functional aspects of these sequences on the pericentromere chromatin were also evaluated. Highlights: A scattered short tandem repeat, typical of Gypsy/TAT LTR retrotransposons, associated with several fragments of other transposable elements, accumulates in the pericentromeres of chromosomes. This arrangement is preserved in all clades of the genus and appears to have a strong regulatory role in the organisation of chromatin around centromeres.
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http://dx.doi.org/10.1139/gen-2021-0045 | DOI Listing |
Genome
March 2022
Laboratório de Citogenética e Diversidade Vegetal, Departamento de Biologia Geral, Centro de Ciências Biológicas, Universidade Estadual de Londrina, Londrina, 86097-570, Paraná, Brazil.
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