title: Centromeric and non-centromeric satellite DNA organisation differs in holocentric Rhynchospora species.
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.
authors.affiliation: Laboratory of Plant Cytogenetics and Evolution, Federal University of Pernambuco (UFPE), Recife, PE, Brazil.
authors.forename: Tiago
authors.initials: T
authors.lastname: Ribeiro
authors.affiliation: Laboratory of Plant Cytogenetics and Evolution, Federal University of Pernambuco (UFPE), Recife, PE, Brazil.|Laboratory of Genetic Resources, Campus Arapiraca, Federal University of Alagoas, Arapiraca, AL, Brazil.
authors.forename: André
authors.initials: A
authors.lastname: Marques
authors.affiliation: Biology Centre of the Czech Academy of Sciences, Institute of Plant Molecular Biology, České Budějovice, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Novák
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Stadt Seeland, Germany.
authors.forename: Veit
authors.initials: V
authors.lastname: Schubert
authors.affiliation: State University of Londrina, Paraná, 86057970, Brazil.
authors.forename: André L L
authors.initials: AL
authors.lastname: Vanzela
authors.affiliation: Biology Centre of the Czech Academy of Sciences, Institute of Plant Molecular Biology, České Budějovice, Czech Republic.
authors.forename: Jiri
authors.initials: J
authors.lastname: Macas
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, 06466, Stadt Seeland, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Houben
authors.affiliation: Laboratory of Plant Cytogenetics and Evolution, Federal University of Pernambuco (UFPE), Recife, PE, Brazil. andrea.pedrosaharand@pq.cnpq.br.
authors.forename: Andrea
authors.identifier: 0000-0001-5213-4770
authors.initials: A
authors.lastname: Pedrosa-Harand
mesh_terms: D002503:Centromere / Q000235:genetics*; D032461:Chromosomes, Plant; D004276:DNA, Satellite; D006570:Heterochromatin / Q000235:genetics; D017404:In Situ Hybridization, Fluorescence; D019684:Magnoliopsida / Q000235:genetics*
chemical_list: D004276:DNA, Satellite; D006570:Heterochromatin
keywords: Chromocentre; Cyperaceae; Heterochromatin; Holocentric chromosome; Rhynchospora; Satellite repeats