Karyotype analysis of obtained tetraploid in medicinal plant (Platycodon grandiflorus)

Platycodon grandiflorus is an important medicinal plant in China. Induction of polyploidy was successfully attempted in this medicinal plant using 0.05% colchicine semi-solid under 72 h by apical shoot tip treatment of young seedlings, and then 50% mutant plants were obtained. It was testified by the chromosome number in mitosis and its karyotype analysis for diploid control and obtained mutants. The results showed that the chromosome number of the diploid plant was 2n=2x=18, whereas the chromosome number of the obtained mutants was 2n=4x=36. The karyotype formula of mutant plant and diploid control were K=2n=4X=36=24m+12sm (4SAT) and K=2n=2X=18=12m+6sm (2SAT), respectively by karyotype analysis and they belonged to 2B and 2A karyotype. It was confirmed that the obtained mutant plants were tetraploid. Key words: Platycodon grandiflorus, Obtained mutants, karyotype analysis.