新疆硬粒小麦5个品种5S rRNA基因重复单元间序列分析

Sequence Analysis of the 5S rRNA Gene Repeat Units in 5 Durum Wheat Species from Xinjiang of China

本研究参照Gen Bank禾本科以及前期新疆7个小麦种5S r DNA NTS序列,通过PCR技术扩增获得新疆5个硬粒小麦品种5S r DNA NTS序列,并通过与5S r RNA序列比对,得到5S r DNA NTS序列结构和边界范围。结果显示:5个硬粒小麦品种均存在两种类型5S r DNA NTS序列且相似程度不同,长NTS序列保守性较高,短NTS片段相对较低;短NTS序列存在两处序列缺失现象,两种类型NTS序列存在不同位置和程度的变异位点和变异频率。利用MEG4.0软件,采用邻接法构建了分子进化树并计算获得了品种间遗传距离。对来自不同品种克隆单元基的序列进行比对,得知对于几个组直向是存在的。直系群体的5S r DNA序列有益于硬粒小麦进一步的系统发育分析。

According to Gen Bank in barley grasses 5S r DNA sequences and previously published 5S r DNA NTS sequences of seven Xinjiang wheat species, 5S r DNA sequences of five durum wheat varieties from Xinjiang were obtained by Polymerase Chain Reaction, the 5S r DNA structure and NTS boundaries were obtained by further alignments with barley grasses 5S r RNA sequence. Sequence analysis revealed that two types of 5S r DNA NTS sequences were presented in five wheat varieties and the nontranscribed spacer of long repeat classes was less variable than that of short repeat classes. Deletion was presented in two parts of 5S r DNA nontranscribed spacer(NTS) length of short repeat class. The different degrees of variable sites and mutation frequency exists in two types of 5S r DNA NTS sequences. Molecular phylogenetic tree was constructed and genetic distance between varieties was calculated by using the MEGA4.0 software and the neighbor-joining method. Sequence comparisons of individual clones(units) isolated from different species have allowed us to confirm that orthology exists for several groups. This demonstration of orthologous groups suggests that the 5S r DNA sequence may be useful for further phylogenetic analysis in the durum wheat species.