基于psbA-trnH序列的十种棘豆属植物分子系统学研究

选择内蒙古28个样地采集的10种棘豆属植物56个单株，提取样品的基因组DNA，对其叶绿体psbA．trnH序列进行扩增、测序，所得序列利用ClustalX软件进行对位排列，并用MEGA5．0软件采用最大似然法构建系统发育树。结果显示：（1）10种棘豆属psbA．trnH序列的变异位点50个，信息位点36个，种间碱基差异百分率为3．4％，GC含量变化范围在23．18％～25．72％之间。（2）棘豆属与黄芪属各为一支，自展支持率达99％，这10种棘豆属植物可能为单系起源。（3）系统树中小叶小花棘豆与小花棘豆的样本独立成一支，支持将小叶小花棘豆作为小花棘豆的变种来处理。（4）多叶棘豆、砂珍棘豆和黄毛棘豆的样本相互混杂，表明亲缘关系很近，支持《内蒙古植物志》将三者归入真棘豆亚属轮叶棘豆组的观点。（5）缘毛棘豆与薄叶棘豆的样本聚成一支。支持将二者归入矮生棘豆组。研究表明，psbA-trnH序列可为棘豆属下种间系统发育关系研究提供分子证据。

Molecular Phylogeny of Ten Species of Oxytropis Based on psbA-trnH Sequences

Total DNA from 56 individual plants collected in 28 sample sites of 10 Oxytropis species in Inner Mongolia was extracted in this research, and the psbA-trnH sequence was amplied and sequenced. Then the sequences were analyzed by ClustalX and MEGA 5.0. The phylogenetic trees were constructed by Maximum Likelihood methods in MEGA 5.0. The results showed as follows ： （ 1 ） There were 50 variable sites, 36 informative site and 3.4% of the inter-specific difference in the 10 Oxytropis species, and the GC contents of the psbA-trnH region were between 23.18% - 25.72%. （2） The 10 species of Oxytropis were probably monophyletic, clearly separating from the Astragalus species and the bootstrap value was 99%. （3） The samples of Oxytropis glabra var. tenuis and O. glabra clus- tered a group independently, thus supported the opinion of treating Oxytropis glabra var. tenuis as a variant of 0. glabra. （4） The samples of O. verticillaris, 0. racemosa and O. ochrantha mixed. Therefore they showed a close relationship. We are congruent with the points in Flora of Intromongolica, the consensus putting the three species into Subgen. Euoxytropis Sect. Baicalia Stell. ex Bunge. （5） The samples of O. ciliata and O. leptophyUa clustered a group, which also supported the consensus which put them into sect. Xerobia Bunge. The investigation results indicated that psbA-trnH sequences provided the molecular evidences for the study of the phylogenetic relationships in the Oxytropis at subgenus, sects and species levels.