中文摘要：

本研究以云南2009—48和广东2010—13为实验材料，通过PCR方法扩增克隆了2种不同的白茅的45SrDNAIGS。序列分析结果表明：云南2009—48的45SrDNAIGS序列长度为2613bp，GC含量为64．6％1广东2010-13的45SrDNAIGS序列长度为2882bp，GC含量64．4％；它们的IGS序列一致性为84．5％。45SrDNAIGS均由NTS和ETS组成：云南2009-48的NTS和ETS长度分别为1441bp和1172bp，GC含量分别为63．5％和66．1％；广东2010—13的NTS和ETS长度分别为1719bp和1163bp，GC含量分别为64．2％和65．3％；它们的NTS序列一致性为76．5％，而ETS的NTS序列一致性高达96．2％。NTS中存在4种类型的亚重复序列（SR1，SR2，SR3，SR4），ETS中存在1种类型的亚重复序列（SR5），序列一致性为74．0％-93．0％。通过软件辅助分析以及与其他植物的比较分析，我们发现了预测的转录起始位点和转录终止位点，并且也存在着大量的甲基化位点，它们在调控rRNA转录方面起着非常重要的作用。此外，聚类分析结果表明白茅与甘蔗的亲缘关系相对较近，为拓宽甘蔗遗传基础提供了理论依据。

英文摘要：

In this study, Yunnan 2009-48 and Guangdong 2010-13 were used as the experiment materials to clone 45S rDNA IGS of two different lmperata cylindrica by PCR. Sequence analysis showed that the length of 45S rDNA IGS of Yunnan 2009-48 was 2 613 bp and GC content was 64.6%. In Guangdong 2010-13, the 45S rDNA IGS was 2 882 bp in length, with 64.4% GC; their sequences identity of IGS was 84.5%. 45S rDNA IGS sequences were all composed of NTS and ETS. In Yunnan 2009-48, the NTS and ETS were 1 441 bp and 1 172 bp in length, and 63.5% and 66.1% in GC content, respectively. While in Guangdong 2010-13, the NTS and ETS were 1 719 bp and 1 163 bp in length, and GC content were respectively 64.2% and 65.3%. The NTS sequence identity of them was 76.5%, but the NTS of ETS sequence identity was up to 96.2%. There were four types of sub-repeat sequences （SR1, SR2, SR3 and SR4） in NTS, whereas only one type of the sub-repeat sequence （SR5） was located in ETS, and the sequence identity ranged from 74.0% to 93.0%. After the software-assisted analysis and comparison with some other plants, we found the predicted transcription start site and transcription termination site, as well as numerous methylation sites, which played an important role in regulating the ribosomal RNA transcription. Furthermore, clustering analysis indicated that Imperata cylindrica had closer relationship with Saecharum, which provided theoretical basis for broadening the genetic basis of Saccharum.