A study on meiotic behaviour in Paeonia anomala subsp. veitchii, Paeoniaceae

Abstract Chromosomal meiotic behaviour in pollen mother cells (PMCs) of Paeonia anomala subsp. veitchii, endemic to China, was investigated in three natural populations represented by 14 individuals. Meiotic abnormalities including bridges, fragments and univalents occurred in all individuals. At metaphase I, mean chromosome configuration of each cell was 2n = 10 = 0.36 I + 4.82 II. Most of the chromosomes were ring bivalents, but some were rod bivalents or univalents. Pairing index ranged from 71.04 to 77.76%. Chromosome bridges, fragments, unequal separation and lagging chromosomes were observed both at anaphase I and telophase I. All individuals produced bridges/fragments (10.37% of PMCs on average) at anaphase I, which suggested that they were all heterozygotes for paracentric inversions. However, there were some variations among individuals in frequency of bridge occurrence and size of fragments, which indicated that many different inversions existed in this subspecies. Further evidence is needed to answer why the structural heterozygosity exists so widely in the subspecies, and whether there is a relationship between this structural heterozygosity and ecological adaptation.