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核rDNA的ITS序列在被子植物系统与进化研究中的应用

王建波,张文驹,陈家宽   

  • 收稿日期:1900-01-01 修回日期:1900-01-01 出版日期:1999-07-10 发布日期:1999-07-10
  • 通讯作者: 王建波

Application of ITS sequences of nuclear rDNA in phylogenetic and evolutionary studies of angiosperms

WANG Jian-Bo, ZHANG Wen-Ju, CHEN Jia-Kuan   

  • Received:1900-01-01 Revised:1900-01-01 Online:1999-07-10 Published:1999-07-10
  • Contact: WANG Jian-Bo

摘要:

 被子植物与其它高等真核生物相似,核rDNA是高度重复的串联序列。由于同步进化的力量,绝
大多数物种中这些重复单位间已发生纯合或接近纯合。核rDNA的内转录间隔区(ITS)包含被5.8S
rDNA所分隔的ITS1和ITS2两个片段,ITSl的长度为187~298bp,ITS2为187~252bp,经PCR扩
增后可以方便地对这两个片段进行直接测序或克隆测序。ITS序列变异较快,可以提供较丰富的变异
位点和信息位点,已证实它是研究许多被子植物类群系统与进化的重要分子标记,不仅可用于解决科、
亚科、族、属、组内的系统发育和分类问题,而且可用于重建多倍体复合体的网状进化关系,探讨异源多
倍体的起源过程,然而,正是由于ITS序列变异较快,它一般不适于科以上水平的系统发育研究。

关键词: ITS序列, 系统发育, 进化, 被子植物

Abstract:

 Nuclear rRNA genes (rDNA) in angiosperms are arranged in long tandem repeat-
  ing units, much like those of other higher eukaryotes. Owing to rapid concerted evolution,
  the repeat units have homogenized or nearly so in most species. The internal transcribed
  spacer (ITS) of nuclear rDNA is composed of ITS1 and ITS2, which are seperated by 5.8S
  rDNA. The two spacers, ITS1 (187~298 bp) and ITS2 (187~252 bp), can be readily
  amplified by PCR and sequenced using universal primers. The sequences contain many vari-
  able sites and potential informative sites among related species, and have been proven to be a
  useful molecular marker in phylogenetic and evolutionary studies of many angiosperm taxa.
  It can be used not only in classification and phylogenetic inferences at the levels of family,
  subfamily, tribe, genus and section, but also in reconstruction of reticulate evolution and de-
  tection of the speciation via hybridization and polyploidization. But this region may not be
  useful for resolving phylogenetic relationships among families or taxa of higher hierarchy ow-
  ing to the rapid variation of the ITS sequences.

Key words: ITS sequence, Phylogenetics, Evolution, Angiosperm