2个产地红景天rDNA-ITS序列及亲缘关系分析

目的: 对我国2个主产区的主要红景天(Rhodiola L.)品种rDNA-内转录间隔区(ITS)序列进行分析,为红景天种质资源的分子鉴别及进化关系提供依据。方法: 提取核基因组DNA,聚合酶链反应(PCR)克隆ITS序列;经DNAstar软件拼接序列后,通过Clustal X软件进行比对,考察其变异位点及信息位点;用Mega 4.1计算品种之间的遗传距离,构建最大简约树(maximum parsimony,MP)和邻接树(neighbor-joining,NJ)。结果: 5种红景天材料rDNA-ITS序列长度为603~604 bp,ITS₁、5.8 S rDNA和ITS₂的DNA长度分别为226 bp、164 bp和213~214 bp。ITS₁和ITS₂分别含有11和9个变异位点,其中,信息位点分别为6和2个;存在转换、颠换、缺失等现象;5.8 S rDNA序列含7个变异位点,2个信息位点;试验中红景天品种的遗传距离为0.018 2~0.627 3。大花红景天与柴胡红景天亲缘关系最近。结论: rDNA-ITS序列是鉴别红景天品种,研究遗传关系的良好方法。

Objective: To provide the evidences for molecular identification, genetic relationship, sequencing and comparison of rDNA-internal transcribed spacer(ITS)sequences of four Rhodiola species and a tissue culture seedling of R.crenulata from two major producing areas in China.Methods: ITS sequences were polymerase chain reaction(PCR)-amplified based on nuclear genome DNA, and then ITS sequences of each sample were spliced by DNA star to further investigate the sequence alignment and screen the informative site and variation point by Clustal X.Genetic distances of all species were calculated with Mega 4.1, and the phylogenetic trees were constructed through the neighbor-joining(NJ)and maximum parsimony(MP)methods.Results: The lengths of ITS sequences ranged from 603 bp to 604 bp.The length of ITS₁, 5.8S rDNA and ITS₂ were 226 bp, 164 bp and 213-214 bp respectively.There were 11 and 9 variation points for ITS₁ and ITS₂, concluding 6 and 2 informative sites respectively.Some transitions, transversions and base deletions were observed.The 5.8 S rDNA sequences were more conserved and there were only 7 variable sites with 2 parsimony information sites.The genetic distance of the test plants in Rhodiola L.ranged from 0.018 2 to 0.627 3, and the smallest genetic distance was observed between R.crenulata and R.bupleuroides.Conclusion: The ITS sequence is a good tool in identification of Rhodiola species and their genetic relationship.