Preliminary Study on the ITS Sequences of nrDNA from Rhodiola alsia

[Objective] The study aimed to analyze the ITS sequences of nrDNA from Rhodiola alisa and investigate the difference of evolution rate between nrDNA and trnS-trnG and rpl20-rps12 sequences of cpDNA(chloroplast DNA).[Method]Total DNA was extracted from silica-dried leaves of R.alsia by using modified CTAB method.With the extracted DNA sample as template,nrDNA ITS region was amplified,then purified and sequenced.In addition,the yielded ITS sequences were also compared with the known trnS-trnG and rpl20-rps12 sequences of cpDNA from R.alsia.[Result]The ITS sequence of nrDNA from R.alsia was 701 bp in length,of which 13 variable sites were found with a percentage of 1.85%.Of the 13 variable sites,8 were caused by point mutations,5 were the results of insertions or deletions.The(A+T)content and(G+C)content were 46.9% and 53.1%,respectively.The nucleotide diversity(π)was 0.004 27.[Conclusion]The ITS region of nrDNA from R.alsia was more conservative and evolved more slowly than the trnS-trnG and rpl20-rps12 sequences of its cpDNA.

基于磁珠富集法开发并筛选西川红景天的微卫星标记

利用FIASCO磁珠富集法,开发和筛选青藏高原特有珍贵植物西川红景天(Rhodiola alsia)多态性微卫星标记。结果表明:用(AG)15和(AC)15两种微卫星标记探针构建富集文库,共获得阳性克隆约2500个;从中随机挑取1200检测,发现具有多态性的阳性克隆达400个;随机挑取200多态性的阳性克隆进行测序,从中获得105个SSR位点,用在线软件primer3-2.3.4成功设计得SSR引物105对;其中45对可以成功扩增,而13对所扩增的片段在相距较远的4个自然居群的24个个体中显示较高的遗传多态性。用4个居群的80个个体检测这13对引物发现,平均等位基因数(A)约为9.192,观测杂合度(Ho)和期望杂合度(He)均值分别约为0.712和0.734,如此高的多态性已经满足后期研究的需要;数个位点在某些居群中显著偏离哈迪温伯格平衡(P<0.01),这可能是实际研究的居群并不能达到哈迪—温伯格定律所假设的无限大等理想状态所致。结合此前基于表达序列标签(Expressed Sequence Tag,EST)序列开发的SSR多态性位点,该研究结果为今后利用SSR位点开展西川红景天的居群遗传结构分析和其他研究提供了一组有效工具。

西川红景天nrDNA ITS序列初步研究

[目的]对西川红景天nrDNA ITS序列进行分析,并与cpDNA(叶绿体DNA)trnS-trnG序列和rpl20-rps12序列进行比较,从而初步比较2套植物基因组的进化速率。[方法]采用改良CTAB法从硅胶干燥的西川红景天叶片中提取总DNA,并对nrDNA ITS区进行扩增、纯化、测序,然后与cpDNAtrnS-trnG和rpl20-rps12序列进行比较。[结果]序列比对后得到长度为701 bp的ITS序列,其中变异位点13处,占总序列的1.85%。在13处变异位点中,8处为碱基置换,5处为插入/缺失。(A+T)含量为46.9%,(G+C)含量为53.1%。核苷酸多样性为0.004 27。[结论]西川红景天nrDNA ITS区域较cpDNAtrnS-trnG序列和rpl20-rps12序列保守,进化速率较慢。