Cytogenetic study of three edible chrysanthemum cultivars

During past decades, edible chrysanthemum (Dendranthema x grandiflorum) has become a popular dietary supplement. However, only numberable cultivars are available, cytogenetic studies especially meiotic behaviour in them remaind largely unexplored. In the present study, we analyzed the karyotype and meiotic behaviour during microsporogenesis in accessions of edible chrysanthemum. This information can be useful in cultivar improvement, as well as in elucidation of the evolution of the species. The three edible cultivars studied all had an intermediate type of interphase nucleus, and their mitotic prophase chromosomes were of the interstitial type. The chromosome number of "Baohuatangyijin" (Bn) varies from 55 to 62. "Zifengmudan" (Zn) has the karyotype 2n = 54 = 38m + + 12sm + 4st, while "Jingxingxiying" (Jg) has 2n = 55 = 38m + 15sm + 2st. Male meiosis was largely normal. Mean pairing configuration ofZn at diakinesis and metaphase I was 0.941 + + 25.07II + 0.14III + 0.63IV, while for Jg, the equivalent was 1.32I + 24.64II + 0.16III + 0.85IV + 0.05V + + 0.04VI. Chromatid separation was normal during anaphase I and anaphase II in most meiocytes. All three edible chrysanthemums appear to be allopolyploid, and the edible type is probably more primitive than the ornamental type. However, the edible type is probably more closely related to the ornamental than to the medicinal type.