Centromeric and non-centromeric satellite DNA organisation differs in holocentric <Emphasis Type="Italic">Rhynchospora</Emphasis> species |
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Authors: | Tiago?Ribeiro André?Marques Petr?Novák Veit?Schubert André?L?L?Vanzela Jiri?Macas Andreas?Houben Email authorView authors OrcID profile" target="_blank">Andrea?Pedrosa-HarandEmail authorView authors OrcID profile |
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Institution: | 1.Laboratory of Plant Cytogenetics and Evolution,Federal University of Pernambuco (UFPE),Recife,Brazil;2.Laboratory of Genetic Resources,Campus Arapiraca, Federal University of Alagoas,Arapiraca,Brazil;3.Biology Centre of the Czech Academy of Sciences,Institute of Plant Molecular Biology,?eské Budějovice,Czech Republic;4.Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben,Stadt Seeland,Germany;5.State University of Londrina,Paraná,Brazil |
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Abstract: | Satellite DNA repeats (or satDNA) are fast-evolving sequences usually associated with condensed heterochromatin. To test whether the chromosomal organisation of centromeric and non-centromeric satDNA differs in species with holocentric chromosomes, we identified and characterised the major satDNA families in the holocentric Cyperaceae species Rhynchospora ciliata (2n = 10), R. globosa (2n = 50) and R. tenuis (2n = 2x = 4 and 2n = 4x = 8). While conserved centromeric repeats (present in R. ciliata and R. tenuis) revealed linear signals at both chromatids, non-centromeric, species-specific satDNAs formed distinct clusters along the chromosomes. Colocalisation of both repeat types resulted in a ladder-like hybridisation pattern at mitotic chromosomes. In interphase, the centromeric satDNA was dispersed while non-centromeric satDNA clustered and partly colocalised to chromocentres. Despite the banding-like hybridisation patterns of the clustered satDNA, the identification of chromosome pairs was impaired due to the irregular hybridisation patterns of the homologues in R. tenuis and R. ciliata. These differences are probably caused by restricted or impaired meiotic recombination as reported for R. tenuis, or alternatively by complex chromosome rearrangements or unequal condensation of homologous metaphase chromosomes. Thus, holocentricity influences the chromosomal organisation leading to differences in the distribution patterns and condensation dynamics of centromeric and non-centromeric satDNA. |
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