河北保定地区苹果锈果类病毒分离物的序列分析

Sequence Analysis of Apple Scar Skin Viroid Isolated From Baoding in Hebei

以采自河北保定的苹果锈果类病毒（apple skin scar viroid,ASSVd）样本为试材,采用用RT-PCR方法对样本中的ASSVd全基因组序列进行扩增,然后利用生物学软件MEGA 6.0对该分离物与已发表的其它分离物序列构建系统发育树,对系统进化关系进行分析。结果表明：ASSVd保定分离物基因组全长332nt,将序列提交到GenBank,登录号为KR264032。该分离物与已发表的其它13个来自不同寄主、不同国家的ASSVd分离物间进化关系极近,核苷酸相似性为92%~99%。与加拿大苹果上的X71599株系亲缘关系最近,相似性为99%,仅在第221位有一个碱基差异,与新疆梨上的JX861259株系亲缘关系最远。系统发育分析表明,不同地区的ASSVd分离物聚类没有规律性,说明ASSVd不存在地区专化性。新疆梨、桃、杏、苹果不在同一分支,说明ASSVd可能存在一定的寄主特异性。二级结构预测表明,该分离物的中央保守区与末端保守区与ASSVd其它序列相同。

The complete genome sequence of apple skin scar viroid（ASSVd）isolated from apple producing region in Baoding city of Hebei Province was clarified by RT-PCR.Then a phylogenetic tree according to the genome sequence of ASSVd BD-1and the other published isolates using biology software MEGA 6.0were constructed.The evolutionary relationship was analyzed.The results showed that the full length genome of ASSVd BD-1was 332 nt,which had been submitted to GenBank（accession number：KR264032）.The isolate had close evolution relationship to the other13 isolates with nucleotide similarity among 92%-99%.ASSVd BD-1showed the highest identity（99%）with the isolate DAVd（GenBank accession number：X71599）from apple in Canada and only one nucleotide difference in 221 st site.It showed the lowest identity with isolate ASSVd-Z7（GenBank accession number：JX861259）from pears in Xinjiang.Phylogenetic analysis showed there was no correlation between the region and molecular variation of ASSVd.The isolates of pear,peach,apricot,apple in Xinjiang were not in the same cluster,which suggested that there was certain correlation between the host type and molecular variation of ASSVd.The result of secondary structure prediction showed that the sequences of the central conserved region and terminal conserved region were identical to the reported ASSVd reference sequence.