基于ITS2序列的十大功劳属植物分子鉴定及亲缘关系分析

Molecular Identification and Genetic Relationship Analysis of Mahonia Based on ITS2 Sequence

目的:基于ITS2序列对十大功劳属植物进行分子鉴定,并确定其亲缘关系。方法:收集十大功劳属植物29份及外类群植物4份,对ITS2区段进行PCR扩增和测序,使用Mega 6.0软件进行序列变异分析,利用ITS2 database在线工具预测ITS2序列二级结构,并采用NJ邻接法构建系统进化树。结果:十大功劳属植物ITS2序列长度均为223 bp,平均GC含量52.5%~55.2%。保守位点共203个,变异位点共20个,种间遗传距离大于种内遗传距离。依据ITS2序列二级结构,可直观地将小果十大功劳、阔叶十大功劳和十大功劳与该属其他植物明显区分。基于ITS2序列的NJ进化树基本可以阐述十大功劳属植物的种间关系。小果十大功劳和十大功劳聚为一支,它们的亲缘关系较为接近。宜章十大功劳以87%的支持率与外类群小檗属植物聚为一支,阔叶十大功劳与绿药淫羊藿聚为一支,说明十大功劳属与小檗属和淫羊藿属的关系也很近。结论:ITS2序列在十大功劳属植物的物种真实性鉴定方面具有良好的应用价值。

Objective:To carry out molecular identification of Mahonia based on ITS2 sequence,and to determine its genetic relationship.Methods:A total of 29 samples of Mahonia and 4 samples of other plants were collected,the ITS2 segment was amplified and sequenced by PCR.Sequence variation was analyzed by Mega 6.0 software.The ITS2 database online tool was used to predict the secondary structure of ITS2 sequences,and the phylogenetic tree was constructed by NJ adjacency method.Results:The ITS2 sequence length of Mahonia was 223 bp,and the average GC content was 52.5%~55.2%.There were 203 conserved loci and 20 variation loci,the interspecific genetic distance was greater than the intraspecific genetic distance.According to the secondary structure of ITS2 sequence,Mahonia bodinieri,Mahonia bealei,Mahonia fortunei could be intuitively distinguished from other plants in this genus.The NJ tree based on ITS2 sequence could basically explain the intraspecific relationship of Mahonia.Mahonia bodinieri and Mahonia fortunei were clustered together,indicating that their genetic relationship was relatively close.Mahonia cardiophylla and Berberis species were clustered together with 87%support rate,and Mahonia bealei and Epimedium chlorandrum were clustered together,indicating that there was close relationship between Mahonia,Berberis and Epimedium.Conclusion:The ITS2 sequence has a good application value in the identification of the species authenticity of the Mahonia plants.