中国桔梗多倍体诱导与鉴定

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40h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。

The Ployploid Induction and Identification of Platycodon grandiflorus (Campanulaceae) in China

In in vitro culture of 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 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.