感染大麦黄矮病毒的小麦中vsiRNA特征分析

Characterization of vsiRNA derived from Barley yellow dwarf virus in infected wheat

RNA沉默是植物中一种保守的抗病毒机制,其以大量病毒来源的小干扰RNA(virus-derived small interfering RNAs,vsiRNAs)的产生为标志,病毒在侵染寄主过程中可通过vsiRNAs靶向寄主转录本以对抗这种防御机制。BYDV-GAV引起的小麦黄矮病导致小麦黄化和矮化症状,对小麦生产构成严重威胁。通过深度测序技术,分析了感染BYDV-GAV的感病小麦品种‘小偃6号’中vsiRNAs的特征,共得到11384个vsiRNAs,并预测到37784个寄主靶基因。发现来源于BYDV-GAV基因组的正义和反义链的vsiRNAs的数量分布大致相等,在5’末端具有A和C偏好性,长度主要在21nt^22nt。靶基因的功能分析表明这些靶基因参与了广泛的生物学功能,尤其是在寄主-病原物互作中占的比重最大。选取25个参与寄主-病原互作的抗性相关基因进行定量验证,发现接种BYDV-GAV后有15个明显下调,6个上调,4个微弱下调,表明测序结果和靶基因预测可靠。推测BYDV-GAV可以通过vsiRNAs干扰寄主抗性基因表达和信号转导,从而实现对感病寄主的侵染。研究结果对揭示BYDV-GAV与小麦互作的分子机制具有重要意义。

A mass of virus-derived small interfering RNAs(vsiRNAs)are caused by the conserved antiviral mechanism of RNA silencing during the process of virus infecting plants.The vsiRNAs target the transcripts of plants to defense the RNA silencing,a conserved antiviral mechanism,for the viral successful infection.Barley yellow dwarf virus-GAV(BYDV-GAV)resulted in an important viral disease in China with yellowing and dwarfing symptoms in winter wheat.Susceptible variety of wheat‘Xiaoyan 6’was infected by BYDV-GAV and the vsiRNAs derived from BYDV-GAV were analyzed using deep sequencing.A total of 11384 vsiRNAs were found,and 37784 host target transcripts were obtained based on the vsiRNAs information.The vsiRNAs number distributed on the sense strand of BYDV-GAV genome was approximately equal to that on the antisense strand.The predominated of vsiRNAs were 21 nt and 22 nt in length,and the nucleotides of A and C were preferred at the 5′-terminus.Functional analysis suggested that the potential target genes of vsiRNAs were involved in a wide range of biological functions,especially the host-pathogen interaction.25 resistance-related genes involved in host-pathogen interaction were screened for qRT-PCR verification.Among of them,15 potential target genes of vsiRNAs were significantly down-regulated,6 were up-regulated,and 4 were weakly down-regulated after the inoculation of BYDV-GAV.The result of qRT-PCR illustrated the reliability of deep sequencing and target gene prediction.Our data revealed that vsiRNAs involved in the host resistance gene expression and signal transduction in the BYDV-GAV infection,which is helpful to understand the molecular mechanism of interaction between BYDV-GAV and wheat.