Zhou Ming-bing, Zhong Hao, Zhang Qin-hui, Tang Ke-Xuan, Tang Ding-Qin
School of Agriculture and Biology, Shanghai Jiao Tong University, 200240 Shanghai, China.
Genetica. 2010 Aug;138(8):861-8. doi: 10.1007/s10709-010-9469-5. Epub 2010 Jun 25.
Ty1-copia retroelements have been found in all major plants and are largely responsible for the huge differences in the genome size. In this study we isolated and sequenced Ty1-copia reverse transcriptase (rt) gene fragments from 44 representative species of bamboo and nine cultivars or forms of Phyllostachys pubescens. Phylogenetic analysis of 72 distinct Ty1-copia rt sequences showed that Ty1-copia retroelements were widespread, diverse and abundant in these species of Bambusoideae subfamily. In addition, a molecular phylogeny of the species of the Bambusoideae subfamily was established by using the internal transcribed spacer sequences of nuclear ribosomal DNA (ITS) sequences. The comparison between ITS- and Ty1-copia rt- based trees is obviously incongruent. The results suggested either the existence of horizontal transfer events between phylogenetically distant species, or an ancestral Ty1-copia retroelement polymorphism followed by different evolution and stochastic losses.
Ty1-copia类反转录转座子在所有主要植物中均有发现，并且在很大程度上导致了基因组大小的巨大差异。在本研究中，我们从44种代表性竹子以及9个毛竹栽培品种或变型中分离并测序了Ty1-copia反转录酶（rt）基因片段。对72个不同的Ty1-copia rt序列进行系统发育分析表明，Ty1-copia类反转录转座子在竹亚科的这些物种中广泛存在、多样且丰富。此外，利用核糖体DNA（ITS）序列的内部转录间隔区序列构建了竹亚科物种的分子系统发育树。基于ITS序列的树和基于Ty1-copia rt序列的树之间的比较明显不一致。结果表明，要么在系统发育关系较远的物种之间存在水平转移事件，要么存在一个祖先Ty1-copia类反转录转座子多态性，随后发生了不同的进化和随机丢失。
