窄叶鲜卑花(Sibiraea angustata)nrDNA ITS和cpDNA trnL-F序列分子进化特点的分析

Characteristic of Molecular Evolution of Sibiraea angustata Based on nrDNA ITS and cpDNA trnL-F Sequence Analysis

应用PCR产物直接测序法分析了窄叶鲜卑花居群间nrDNA(核糖体DNA)ITS序列和cpDNA(叶绿体DNA)trnL-F的碱基差异,并与cpDNAtrnS-G序列和rpl20-rps12序列进行比较,从而初步研究两套植物基因组的变异速率。采用改良的CTAB法从硅胶干燥的窄叶鲜卑花叶片中提取总DNA,并对nrDNA ITS和cpDNAtrnL-F区域进行扩增、纯化、测序。nrDNA ITS序列共有601 bp,有变异位点3处,变异位点百分率为0.05%,(G+C)含量为41.4%。cpDNAtrnL-F序列共有927 bp,有变异位点1处,变异位点百分率0.01%,(G+C)含量为32.6%,两种序列的核苷酸多样性非常低。比较发现,窄叶鲜卑花nrDNA ITS区域较cpDNAtrnS-G序列和rpl20-rps12序列保守,变异速率较慢,比cpDNAtrnL-F序列变异速率稍快。通过对ITS序列单倍型(haplotype)进行分析发现,窄叶鲜卑花现有分布范围经历了居群近期范围扩张,与叶绿体基因组(trnS-G和rpl20-rps12序列)得出的结论一致。因此,窄叶鲜卑花nrDNA ITS序列适合该种的谱系地理学研究。

The differences between the nrDNA ITS and cpDNA trnL-F sequences in Sibiraea angustata were analyzed by PCR direct sequencing,and then compared with cpDNA trnS-G,rpl20-rps12 sequences of this species.Total DNA was extracted from silica-dried leaves of S.angustata using modified CTAB method.With the extracted DNA as template,nrDNA ITS and cpDNA trnL-F regions were amplified,then purified and sequenced.The length of nrDNA ITS sequence of S.angustata was 601 bp,of which 3 were variable sites with a percentage of 0.05%,the（G＋C） content was 41.4%.The length of cpDNA trnL-F sequence of S.angustata was 927 bp,of which only one was variable site with a percentage of 0.01%,the（G＋C） content was 32.6%.The nrDNA ITS region of S.angustata was more conserved and evolved more slowly than the cpDNA trnS-G and rpl20-rps12 sequences,but evolved a little more rapidly when compared to cpDNA trnL-F.The present distribution range of S.angustata has experienced range expansion by the haplotype analysis of this species,which consists with the conclusion resulting from cpDNA genome.Therefore,the nrDNA ITS sequence of S.angustata was fit to the phylogeographic study of this species.