侵染梨的苹果茎痘病毒基因组序列及小RNA分析

Study on genome sequence and small RNA of Apple stem pitting virus infecting a pear plant

苹果茎痘病毒(Apple stem pitting virus,ASPV)是危害梨(Pyrus spp.)和苹果(Malus spp.)的重要病毒。本研究采用小RNA深度测序技术获得了ASPV基因组的部分序列,在此基础上设计引物对该病毒基因组进行RT-PCR扩增,通过序列拼接得到1个来源于玉露香(Yuluxiang)梨的ASPV分离物(YLX)长度为9 291个核苷酸(nt)(不包括基因组5'末端约30个核苷酸)的基因组序列,该序列与已报道的13个ASPV分离物的基因组核苷酸序列相似性为71.6%~80.7%,与多个来自苹果的ASPV分离物系统进化关系较近。首次分析了来源于ASPV基因组的干扰性小RNA(siRNA),发现来源于ASPV基因组链和互补链的siRNA长度均以21 nt和22 nt为主,siRNA的5'端具有一定的碱基偏好性。本研究结果为深入了解ASPV的分子特性提供了重要信息。

Apple stem pitting virus（ASPV）is an important virus infecting pear （Pyrus spp.） and apple （Malus spp.）. In this study, partial genomic sequence of an ASPV isolate infecting a pear cv. Yuluxiang was assembled from small RNAs （sRNAs） obtained by taking next generation sequencing （NGS）. Then RT-PCR assays were performed to amplify genome of the ASPV isolate YLX. The ASPV-YLX genome consisting of 9 291 nucleotides （nts） （excluding about 30 nts in the un-translation region at the 5＇ end of the genome）, shared similarities ranging from 71.6% to 80.7% with that of 13 reported ASPV isolates and showed a relatively close phylogenetic relationship with several ASPV isolates from apple trees. For the first time the small interference RNAs （siRNA） derived from ASPV-YLX genome were analyzed. A profile with prevalent sizes of 21- and 22-nt was observed for both its genomic and anti-genomic siRNAs. Our result revealed the nucleotide prevalence at the 5＇-terminal of siRNAs derived from genomic and anti-genomic RNAs. Results presented in this study provide important information for further understanding the molecular characteristics of ASPV isolates.