毛头鬼伞中一条新28S rRNA的发现及其同源性分析

Finding and Homological Analysis of a New 28S rRNA Sequence Isolated from Shaggy Mane (Coprinus comatus)

本研究从担子菌毛头鬼伞(Coprinus comatus)菌丝中分离获得一条新的28S rRNA序列,序列长度为906bp(GenBank accession No.GU568178)。该序列是我们前期在从毛头鬼伞中克隆一种烟草花叶病毒(TMV)的抗性蛋白基因y3时意外获得的一条非目的条带。将此获得的序列通过NCBI的BLAST,以及与其同源序列进行Clustal w和MEGA聚类分析,证实该序列是28S rRNA,同时还发现毛头鬼伞的系统进化关系比较离散。此外,在这一新28S rRNA与TMV的抗性蛋白基因y3之间发现有两个同源区段有可能是PCR扩增y3基因时出现非目的条带的原因。在这两个同源区段中,其一区段与克隆y3基因时所用的PCR引物之一有较高的相似性,另一区段也是一般PCR引物的类似物。本研究中新28S rRNA序列的获得是PCR扩增中出现非目的条带的新例,该序列的发现及聚类分析的结果有助于真菌基因组学研究及真菌生物分子分类系统的建立。

In this study,we have found a new 28S rRNA sequence with 906 bp in length （GenBank accession No. GU568178） which isolated from mycelia of basidiomycete shaggy mane （Coprinus comatus）,and the sequence was an untargeted band obtained unexpectedly when we previously cloned TMV-inhibitor y3 gene from this shaggy mane. The acquired sequence was used to search homologous sequences by using BLAST algorithm in NCBI,and it was performed to cluster with its homologues by using the Clustal w and MEGA methods. The results confirmed that the sequence was a new 28S rRNA of ribosomal large-subunits,and the phylogenic relationship of Coprinus comatus was found to be dispersed from one anothers. Moreover,two homologous counterparts between the sequences of new 28S rRNA and the TMV-inhibitor gene y3 were found possibly to be the cause of formation of the untargeted band in PCR amplification of y3 gene. Within these two homologous counterparts,one counterpart had the sequence similar to a PCR primer for y3 gene,and the other one was a primer-like fragment. In this research,obtaining of the new sequence of 28S rRNA was an updated example of the formation of untargeted bands during PCR amplification. Then the finding and clustering analysis results of 28S rRNA would be helpful for researches in fungus genomics and the establishment of theirs molecular classification system.