Variation of Satellites and Localization of rRNA Genes in Peony Chromosomes

Abstract

All 4 peony plants examined, Paeonia japonica Miyabe and Takeda, P. obovata Maxim., P. lactiflora Pall. cv. kumoinotsuru (Higo-peony), and P. lectiflora Pall. medical peony, had a diploid chromosome number of 2n=2x=10. Their karyotypes, also, were very similar or the sameand were constituted from 2 sets of chromosomes A to E. Nevertheless, the SAT-chromosome, hybridization signal of rRNA genes in interphase nuclei, and number of nucleolus per cell variedamong individuals and plants. The signals of rRNA genes in metaphase localized at the distal ends of homologous chromosomes A, B, D and E (8 signals) in P japonica and 2 kinds of P. lactiflora, and at the distal ends of homologous chromosomes B, D and E (6 signals) in P obovata. In conclusion, it is considered that variations in the number of satellites, signals of rRNA genes in interphase nuclei and nucleoli per cell can be attributed to the grade of interaction of rRNA genes.