罗田甜柿Ty1-copia类逆转座子RNaseH-LTR序列的分离和特性分析

Isolation and Characterization of RNaseH-LTR Sequences of Ty1-copia Like Retrotransposons in Oriental Persimmon (Diospyros kaki Thunb.‘Luotian-tianshi’)

逆转座子序列信息的获得,对了解其在基因组中的行为及系统学研究有重要价值。本试验从罗田甜柿(Diospyros kaki Thunb.‘Luotian-tianshi’)基因组中分离出31个RNaseH-LTR(long terminal repeat,长末端重复)序列,并利用逆转座子间扩增多态性(inter-retrotransposon amplified polymorphism,IRAP)技术对部分序列相应的逆转座子家族在柿属植物中的转座活性及分布情况进行初步探讨。序列分析结果表明,至少有10个Ty1-copia类逆转座子家族得到扩增;其家族间普遍表现高度异质,碱基替换、插入或缺失突变,以及翻译成氨基酸后发生不同程度的终止密码子突变、氨基酸取代和移框突变等,是产生高异质性的原因;此外,其家族内部某些序列间的相似性极高,可能是寄主基因组与逆转座子间互惠关系的体现。应用部分逆转座子引物的IRAP分析结果表明,相应的逆转座子家族在柿属植物中普遍存在,其分布广泛,拷贝数高,转座活性强,具有进一步开发为多种逆转座子分子标记的潜力。

It is important to obtain sequence information on retrotransposons for detecting their behavior in the host genome and for studing the phylogenetic relationship in many crops. Thirty-one RNaseH-long termi-nal repeat （LTR） sections of the Ty1-copia like retrotransposon clones were isolated from oriental persimmon （Diospyros kaki Thunb. ＇ Luotian-tianshi＇ ） successfully, and IRAP （ inter-retrotransposon amplified polymor-phism） analysis were performed in order to illustrate retrotransposon groups corresponding to several sequences transcriptional activity and distribution in oriental persimmon genome. Both sequence multiple alignment and the phylogenetic analysis indicated that at least ten subgroups were amplified, and high sequence heterogeneity that was due to nucleotide replacement, insertion or deletion and amino acid replacement, stop codon and frameshift mutations in translated putative amino acid sequences were found among the different subgroups. But some clones showed high similarity within the same subgroup, it may exhibit the mutual benefit relation-ship between the host genome and retrotransposons. The IRAP analysis suggested that retrotransposon were ubiquitous, generally dispersed, high copy and high transcriptional activity in Diospyros spp. , and their multi-ple insertion patterns indicated that the potential of these RNaseH-LTR sequences for developing novel retrotransposon molecular markers.