西鄂尔多斯特有种四合木与同生境下蒺藜科三个种的核rDNA ITS的序列比较研究

A Comparison of ITS Sequences of Nuclear Ribosomal DNA between Endemic Species Tetraena mongolica Maxim in ORDS Platean and Three Species of Zygophyllaceae in the Same Habitat

为揭示分布于西鄂尔多斯高原的中国特有种四合木对生境的适应性及与其他属的亲缘关系,用PCR直接测序方法,对四合木与同生境蒺藜科(Zygophllyaceae)其他3个种的核糖体DNAITS片段进行了序列分析.结果表明,4种植物在ITS片段长度、GC百分含量和变异位点数上均存在一定差异.ITS1长177～212bp,ITS2长218～237bp;GC含量为57.7%～62%,信息位点比例30.1%.系统发育分析表明,四合木(TetraenamongolicaMaxim)与霸王(ZygophyllumxanthoxylumMaxim)在系统位置上较相近,白刺(NitrariasibiricaPall)与蒺藜(TribulusterrestrisL.)较相近.ITS所揭示的亲缘关系与这些种的形态学和胚胎学特征相似.

The phylogenetic relationships between T.mongolica and other three species of Zygophyllaceae were analyzed based on their nucleotide sequences of the internal transcribed spacer (ITS) of the 18-26s nuclear ribosomal DNA.The sequences were obtained by PCR technique.The results showed that there were differences in the length of sequences,contents of G+C and numbers of variable site among the four species. The length of ITS1 sequences ranged from 177 to 212 bp and ITS2 from 218 to 237 bp,The fragments of ITS2 were longer than that of ITS1.The contents of G+C ranged from 57.7% to 62%.Phylogenetic analysis indicated showed that T. mongolica was close to Z. Xanthoxylum in systematic position.Nitraria sibirica and Tribulus terrestris almost same in the fragments of ITS2, but different in ITS1.The results were similar to the achievements in the research of morphology and anatomy.It reflected their universality and peculiarity of evolutionary process to fit the environment.