青藏高原东南部山丹nrDNA ITS和cpDNA petB/petD 序列的分子进化特点

采用改良CTAB法提取青藏高原东南部山丹25个居群所有个体的基因组DNA，选取核基因ITS和叶绿体petB/petD区域进行PCR扩增、纯化和测序。对所有序列对位排列，其中ITS序列总长696bp，变异位点有4处，共产生7种单倍型，变异位点百分率为0.72%，（G+C）含量60.4%；petB/petD序列总长616bp，仅1处变异位点和2种单倍型，变异位点百分率为0.16%，（G+C）含量34.6%。表明山丹中，petB/petD区域较ITS序列保守，变异速率较慢。对ITS序列单倍型进行失配分布和中性检验分析发现，山丹现有分布范围可能经历了近期居群小范围扩张，AMOVA分析发现山丹居群的遗传变异主要存在于居群内，N_ST >G_ST（P>0.01），表明山丹的遗传变异有着不显著的谱系地理结构。因此，山丹ITS序列适合该种的谱系地理学研究。

Characteristic of Molecular Evolution for Lilium pumilum Redouté on Southeast of the Qinghai-Tibetan Plateau using nrDNA ITS and cpDNA petB/petD Sequence Analysis

In this study, total DNA was extracted from Lilium pumilum on southeast of the Qinghai-Tibetan Plateau using modified CTAB method. Using genome DNA as template, nrDNA ITS and cpDNA petB/petD regions were amplified, purified and sequenced. By sequence alignment, it was known that length of nrDNA ITS sequence was 696 bp, of which 4 variable sites with a percentage of 0.72% were found., The G+C content of the ITS sequence was 60.4% and 7 haplotypes were produced. The length of cpDNA petB/petD sequence was 616 bp, of which 1 was variable sites with a percentage of 0.16% was found. The G+C content of the sequence was 34.6% and 2 haplotypes were found. The petB/petD region of L.pumilum was more conserved than ITS sequences and evolved more slowly. The present distribution range of L.pumilum has probably experienced range expansion by the haplotype analysis of mismatch distribution and neutral test, and AMOVA analysis showed that the genetic variation of L.pumilum mainly existed within populations. The N_ST >G_ST(P>0.01)further showed that there was no significant phylogeographic structure of genetic variation in L.pumilum. Therefore, the nrDNA ITS sequence of L.pumilum was more suitable for phylogeographic study of this species.