稻属核糖体内转录间隔区的遗传多样性分析及系统学意义.docVIP

 稻属核糖体内转录间隔区的遗传多样性分 析及系统学意义 # 5 10 15 20 25 30 35 40  摘要：通过对稻属 AA,BB,CC,EE,FF,GG,CCDD,BBCC8 种基因组型, 21 个种 74 个品种的 ITS 序列进行了序列比较和系统分析,结果表明稻属变异位点占 67.48%,信息位点占 36.30%;ITS 长度在 414-460 之间.PAUP 和 Mega 软件系统分析发现.利用 ITS 序列可明显区分稻属不同基 因型,AA 基因组归为一支,CCDD,CC,EE 基因组归为一支,而 BB,BBCC 为另一支,说明 CC,EE 较 BB 有更近的亲缘关系,CCDD 与 EE 亲缘关系较近;AA 基因组内不同种之间亲缘关系比较 复杂,但能较好区分栽培稻种内籼粳稻。 关键词：稻属；内转录间隔区 ITS；系统树 中图分类号：S332.2 Analysis of ITS sequences of nuclear ribosomal DNA on Oryza L.and their phylogenetic implications DAI xiaojun (College of Life Sciences, Hunan Normal University, Changsha 410081, China) Abstract: In the study, the internal transcribed spacer(ITS) sequences of nuclear ribosomal DNA of the genus Oryza.L(a total of 57 accessions belonging to 21 species of 8 genomes) were cloned and sequenced. The results revealed the length of ITS sequences varied from 414bp to 460bp in which 298 characters(67.48%) were variable and 167 characters(36.30%).were informative. Two phylogenetic trees were reconstructed using neighbor-joining and maximum parsimony methods based on ITS fragments of Oryza L.which the topologies were similar. two main clusters were identified, one well-defined cluster is formed by total AA genomes, in the other cluster, CC,DD and CCDD genomes formed one clade, BB and BBCC formed the other one. This indicated that CC and EE has closer relationship than with the BB genome. CCDD and EE have closer relationship. It is limited to distinguish the interspecific and intraspecific relationships of the AA genome using ITS sequences, nevertheless ,to Oryza.sativa species, indica and japonica subspecies formed separate clades clearly. Key words: Oryza.L; internal transcribed spcer(ITS); phylogenetic tree. 引言 高等植物的细胞核中，编码核糖体 RNA 的基因是高度重复的串联序列。其中编码 18S、 5.8S 和 26S 的 rDNA 为一个转录单位，在该转录单位中，ITS(internal transcribed spacers)是 介于 18S 和 5.8S 之间(ITS1)以及 5.8S 和 26S 之间(ITS2)的非编码转录区。编码 18S、5.8S 和 26S 的序列为高度保守区，ITS 序列为进化速度较快的中度保守序列，且各重复单元间具有 同步进化的特点。因此，ITS 作为基因标记很快成为在序列水平上探讨系统发育和进化研究 的有效手段[1-5]。相比之下，ITS