10种棘豆属植物的trnL-F序列及其分子系统学研究

选择内蒙古27个样地采集的10种棘豆属植物54个单株,提取样品的基因组DNA,对其叶绿体trnL-F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,以探讨棘豆属的种间关系与系统进化.结果显示:(1)10种棘豆属trnL-F的变异位点54个,信息位点46个,种间碱基差异百分率为1.9％,GC含量变化范围在30.69％～31.50％之间.(2)棘豆属与黄芪属各为一支,自展支持率达99％,支持棘豆属植物为单系起源.(3)系统树中小花棘豆的样本自成一支,为相对独立进化；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,从而支持《内蒙古植物志》将三者归入真棘豆亚属轮叶棘豆组的观点.(4)刺叶柄棘豆的样本不同样地形成2个分支,对其亚属水平上的分类需进一步探讨.(5)缘毛棘豆与阴山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,trnL-F序列可为棘豆属下种间系统发育关系研究提供分子证据.

trnL-F Sequences Analysis and Molecular Phylogeny of 10 Species of Oxytropis

Total DNA from 54 individual plants collected in 27 sample sites of 10 Oxytropis species in Inner Mongolia was extracted in this research,and the trnL-F sequence was amplied and sequenced.Then the sequences were analyzed by ClustalX and MEGA 5.0.The phylogenetic tree was constructed by Maximum Likelihood methods in MEGA 5.0.The results showed as follows:(1)In the 10 Oxytropis species,there were 54 variable sites,46 informative sites and 1.9% of the inter-specific difference,and the GC contents of the trnL-F region were between 30.69%~31.50%.(2)The Oxytropis sp.were monophyletic,clearly separating from the Astragalus sp..The bootstrap value was 99%.(3)The samples of Oxytropis glabra itself clustered a group which was relatively evolved independently.The samples of O.verticillaris,O.racemosa and O.ochrantha mixed.Therefore they showed a close relationship.We are congruent with the points in Flora of Intromongolica,which consensus putting the three species into Subgen.Euoxytropis Sect.Baicalia Stell.ex Bunge.(4)Different samples of O.aciphylla were divided into two major branches,and the taxonomic position of O.aciphylla at subgenus level needs further investigation.(5)The samples of O.ciliata and O.inschanica clustered a group,which also supported the consensus which put them into Sect.Xerobia Bunge.The investigation results indicated that trnL-F sequences provided the molecular evidences for the study of the phylogenetic relationships in the Oxytropis at subgenus,sects and species levels.