The 5S rDNA and their chromosomal loci in autotriploid Carassius auratus

Abstract Background Polyploidization can induces a flurry of genetic events and plays an important role in speciation. In this study, we comparatively analyzed the molecular organization and chromosomal locus of 5S rDNA in natural autotriploid (3nCC, 3n=150) and artificial autotriploid gynogenetic (3nG, 3n=150) Carassius auratus as well as the related diploid ancestors, diploid Carassius auratus (2nCC, 2n=100) and Carassius auratus red var. (RCC, 2n=100), which provide a excellent model to ascertain the genomic changes in autotriploidization process. Results The similarities of the 5S rDNA coding region (class I, class II and class III) between RCC and 3nG were 98.3%, 100% and 99.1%, respectively, and the similarities of the 5S rDNA coding region (class IV, class V and class VI) between 2nCC and 3nCC were 97.5%, 100% and 100%, respectively. Fluorescence in situ hybridization (FISH) with 5S rDNA as probe indicated that the expected numbers of maternal chromosomal loci were found in 3nG and 3nCC, respectively. Conclusions These observations indicate that autotriploidization has little influence on the divergence of 5S rDNA family in Carassius auratus.