Abstract: Meiosis behaviors of D. nankingense ( 2x) , D. lavandulifilium ( 2x) , D. nankingense(4x) , D. morifolium ‘Chuju’ (6x) , D. morifolium ‘Huangying’ (6x) and part of interspeicific hybrids between them were studied. The results were concluded as following: The chromosome pairing configuration in meiosis MI per PMC of diploid D. nankingens and D. lavandulifilium was 0.83Ⅰ + 8.58Ⅱ and 1.50Ⅰ+8.25Ⅱ, respectively. The chromosome pairing configuration in meiosis MⅠ per PMC of tetraploid D. nankingense (4x) was 2.64Ⅰ + 13.35Ⅱ + 1.03Ⅲ + 0.93Ⅳ. The chromosome pairing configuration in meiosis MⅠ per PMC of hexaploid D. morifolium ‘Chuju’and D. morifolium ‘Huangying’were 0.48Ⅰ + 26.09Ⅱ+ 0.33Ⅳ and 1.09Ⅰ + 25.18Ⅱ + 0.18Ⅲ + 0.50Ⅳ, respectively, which elucidated that they were two allohexaploids with diploidization meiotic behavior, as well, there were structural changes as translocation on some
chromosomes. The chromosome pairing configuration in meiosis MⅠ per PMC of D. nankingense ×D. lavandulifilium was 1.61Ⅰ + 8.19Ⅱ. Chromosome configuration per PMC in MⅠ was 3.42Ⅰ + 8.34Ⅱ + 1.53Ⅲ+ 0.58Ⅳ in F₁ hybrids of D. nankingense (4x) ×D. nankingense (2x) and 3.62Ⅰ + 8.31Ⅱ + 1.50Ⅲ +0.56Ⅳ in that of D. nankingense (2x) ×D. nankingense (4x). Meiotic association per PMC in MⅠ of F₁ hybrids of D. nankingens ×D. morifolium ‘Huangying’, D. morifolium ‘Huangying’ ×D. nankingens,D. lavandulifilium ×D. morifolium ‘Huangying’and D. morifolium ‘Huangying’ ×D. lavandulifilium were 0.30Ⅰ + 16.45Ⅱ + 0.70Ⅳ, 0.29Ⅰ + 16.07Ⅱ + 0.89Ⅳ, 0.63Ⅰ + 16.32Ⅱ + 0.68Ⅳ and 0.47Ⅰ + 16.38Ⅱ + 0.65Ⅳ + 0.03Ⅵ, respectively. Chromosome configuration in meiosis MⅠ per PMC of F₁ hybrids of D. nankingense (4x) ×D. morifolium ‘Chuju’was 3.59Ⅰ + 18.03Ⅱ + 0.98 Ⅲ + 0.52Ⅳ + 0.07Ⅴ.The results indicated that the genetic relationship between D. nankingense and D. lavandulifilium was closely,and D. nankingense, D. lavandulifilium or some of their relatives were the pregenitor of one genome of cultivating chrysanthemum. The degree of differentiation of three genomes in genus Dendranthema was low and the homology of the three genomes was high. Meanwhile, Structural changes such as translocation were likely to
happen in some chromosomes, and pairing-promotion genes existed in genus Dendranthem a widely.

Key words: Dendranthema, Interspecific hybrids, Meiosis, Genetic relationship