Satellite DNA repeats (or satDNA) are fastevolving 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 satDNAwas 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