Chromosome Structural Heterozygosity In Paeonia (Paeoniaceae): Evidence From Paeonia Decomposita And P. Intermedia

The genus Paeonia (Paeoniaceae) comprises about 35 species of shrubs and perennial herbs which are grouped into three sections: Sect. Moutan, Sect. Onaepia and Sect. Paeonia. Paeonia intermedia Meyer belongs to Sect. Paeonia and P. decomposita Handel-Mazzetti belongs to Sect. Moutan, a section endemic to China. The basic chromosome number is x = 5 in all the species of the genus, and the shortest chromosome, the fifth, is telocentric chromosome and is strikingly recognizable for its unique arm ratio.Meiosis of 22 individuals from three natural populations in P. intermedia and 13 individuals from two natural populations in P. decomposita was investigated in this dissertation. The meiotic aberrances occurred so broadly that all individuals were found with certain amount of bridge, fragment and univalent. Results showed that at metaphase I, on average, 2.17 rod bivalents and 2.7 ring bivalents were observed per pollen mother cell (PMC) of Population One, 2.04 rod and 2.86 ring of Population Two, and 2.21 rod and 2.71 ring of Population Three in P. intermedia; 2.09 rod bivalents and 2.81 ring bivalents were observed per pollen mother cell of Population One, 1.85 rod and 3.08 ring of Population Two in P. decomposita.Mean meiotic chromosome configurations were 2n = 10 = 0.25 I + 4.87 II in...