Résumé
<p><b>OBJECTIVE</b>ITS2 of DNA barcoding was used to study genetic polymorphism of Platycodon grandiflorum.</p><p><b>METHOD</b>Total genomic DNA was isolated from P. grandiflorum. PCR was used to amplified the region of internal transcribed spacer 2 (ITS2), and PCR products were sequenced. The sequences of ITS2 were analyzed and compared by Clustal. The intraspecies genetic distance was calculated based on Kimura 2-parameter model by using MEGA 5.05. The ITS2 sequence of Codonopsis pilosula was used as the outreach value for plants of the genus, and the phylogenic tree used constructed by Neighbor-Joining (NJ) method.</p><p><b>RESULT</b>The K2-P's genetic distance of all samples were ranged from 0 to 0.930. The K2-P's genetic distance of samples at the same area were ranged from 0 to 0.178. The K2-P's genetic distance of samples at different areas were ranged from 0.735 to 0.930. The analytical result showed that the degree of genetic variation were heavy in intraspecies of P. grandiflorum and significantly correlated with geographical location.</p><p><b>CONCLUSION</b>The DNA barcoding of ITS2 can applied to study the intraspecific genetic diversity, it provides a reference for further development of DNA barcoding technology applications.</p>