Abstract: In in vitro culture , Platycodon grandiflorus was treated with colchicine at different concentration and time duration. It showed that the induction rate could reach 50% with colchicine at 0.1% for 40 h. Compared with the normal
diploid plants, the polyploid plants had thicker leaves and larger leaves, darker leaf color , stronger stems with longer length per stem stalk, larger stomata and fewer stomata per unit area. Cytological observation showed the chromosome number of variant plants is 2n=4x=36, while that of normal diploid plant is 2n=2x=18, x=9. Therefore, the variant plants (2n= 4x=36) belong to tetraploid plants. Karyotype formula of the former is 2n=2x=14m+ 20sm+ 2st, and that of the latter is 2n=4x=7m+10sm+1st. Both of the karyotype belong to Stebbins’s 2B type. It was also found that a few induced plants were aneuploid .

Key words: Platycodon grandiflorus

摘要： 在离体培养条件下, 比较了不同浓度、不同处理时间的秋水仙素对中国桔梗( Platycodon grandiflorus A. CD) 进行染色体加倍的诱导效果。结果表明: 用含0 . 1%秋水仙素处理40 h 后诱导频率可达50% , 诱导效果最佳。经秋水仙素诱导后形成的多倍体植株与原二倍体植株比较, 在形态上, 多倍植株叶片变宽变大, 叶色变深, 茎变粗且节距长, 气孔增大而单位叶面积气孔数目减少。对变异植株进行细胞学研究发现, 体细胞中期染色体数目为2n = 4x = 36 , 而原二倍体的染色体数目为2n = 2x = 18 , 基数x = 9 , 因此, 变异植株(2n = 4x= 36) 为四倍体。前者的核型公式为2n = 4x = 14m + 20sm + 2st , 核型属于2B; 后者的核型公式为2n = 2x = 7m+ 10sm+ 1st , 核型也属于2B。检测发现有少数个体有非整倍体变异。

关键词: 中国桔梗, 多倍体诱导, 形态学和细胞学鉴定FONT