Polyploidy induces centromere association

Many species exhibit polyploidy. The presence of more than one diploid set of similar chromosomes in polyploids can affect the assortment of homologou s chromosomes, resulting in unbalanced gametes. Therefore, a mechanism is r equired to ensure the correct assortment and segregation of chromosomes for gamete formation. Ploidy has been shown to affect gene expression. We pres ent in this study an example of a major effect on a phenotype induced by pl oidy within the Triticeae. We demonstrate that centromeres associate early during anther development in polyploid species. In contrast, centromeres in diploid species only associate at the onset of meiotic prophase, We propos e that this mechanism provides a potential route by which chromosomes can s tart to be sorted before meiosis in polyploids. This explains previous repo rts indicating that meiotic prophase is shorter in polyploids than in their diploid progenitors. Even artificial polyploids exhibit this phenotype, su ggesting that the mechanism must be present in diploids, but only expressed in the presence of more than one diploid set of chromosomes.