基于ITS2条形码的桔梗药材遗传多样性研究

目的:利用ITS2条形码探讨不同产地桔梗的遗传多样性。方法:提取桔梗药材DNA,PCR扩增基于进化速率较快的DNA内部转录间隔区2(ITS2)序列并测序,采用Clustal比对分析不同产地桔梗ITS2序列,应用MEGA 5.05软件计算种内Kimura 2-parameter(K2-P)遗传距离,以桔梗科党参属植物党参的ITS2序列为外展值,运用邻接法(neighbor-joining method)构建桔梗系统进化树。结果:试验所用全部样本的K2-P遗传距离为0~0.930,相同地区来源的样本K2-P遗传距离分布于0~0.178,不同地区来源的样本K2-P遗传距离为0.735~0.930;分析结果表明,桔梗种内遗传变异程度巨大,与其地理位置显著相关。结论:ITS2条形码适用于桔梗种内遗传多样性研究,为进一步拓展DNA条形码技术的应用提供了参考。

Study on genetic polymorphism of Platycodon grandiflorum based on barcoding of ITS2

Objective: ITS2 of DNA barcoding was used to study genetic polymorphism of Platycodon grandiflorum. Method: 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. Result: 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. Conclusion: 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.