核rDNA ITS分子标记在兰科植物研究中的应用

Application of Nuclear rDNA Molecular Markers in Study on Orchidaceae

在植物基因组中核rDNA是高度重复的串联序列,其中18S rDNA与5.8S、26S rDNA共同构成一个转录单位。ITS(基因内转录间隔区)分布在18S-5.8S-26S区域,该区域包括3个部分:ITS1和ITS2以及位于它们之间高度保守的5.8S rDNA外显子区。兰科(Or-chidaceae)是单子叶植物中的第一大科,进化程度较高。文中介绍了ITS序列的结构特点,重点对ITS序列在兰科植物近缘种亲缘关系鉴定、系统进化及分子系统地理学研究中的应用及前景进行了综述。

The nuclear rDNA genes occur as high tandem repeats in the plant genome. 185 rDNA and 5.8S, 265 rDNA constitute a transcription unit. The internal transcribed spacer （ITS） is intercalated in the 16S-5.8S-265 region separating the elements of the rDNA locus. The ITS region consists of three parts： the ITS1, ITS2 and the highly conserved 5.8S rDNA exon located between them. These consecutive gene blocks, consisting of several regions, are widely applied in plant phylogenetics. Orchidaceae is the first branch of monocotyledon and has a higher rate of evolution. The structure characteristics of ITS sequence were introduced, its application in Orchidaceae closely related species identification, phylogenetic and molecular phylogeography research were reviewed, the prospect was forecasted.