Abstract A study on the organization of prophase I chromatin in a PTH (permanent translocation heterozygosity) plant -Rhoeo spathacea was carried out. The sequential DAPI/AMD-FISH technique showed that nuclear polarization and centromere clustering during preleptotene-pachytene is a striking feature of all the studied heterozygotic clones. It was revealed that during pachytene pericentromeric heterochromatins assemble into a strikingly regular continuous ring with empty space inside. The topological constraints exerted by the heterochromatic pachytene “ring” exclude both random and multiple centromere interactions, and together with peripheral disposition of GC-rich pericentromeric regions and their reduced number, conform to a condition where one pericentromere interacts side-by-side with its two neighbors. The relation of the meiotic centromere associations in Rhoeo to the processes regulating chromosome arm juxtaposition (e.g. synapsis) and/or segregation was discussed.