病毒感染海洋球石藻Emiliania huxleyi的转录组分析

Transcriptome analysis of marine microalga Emiliania huxleyi in response to virus infection

海洋球石藻Emiliania huxleyi及其特异性裂解病毒E.huxleyi virus(EhVs)在调节海洋碳、硫循环及全球气候变化中起着重要作用,也是开展真核生物病毒–宿主相互作用研究的良好模型系统之一。为了探究病毒感染条件下E.huxleyi基因表达水平的变化,以海洋球石藻E.huxley–BOF 92及其专一性裂解病毒EhV-99B1为研究对象,利用Illumina HiSeq 2000高通量测序技术,分别对E.huxleyi病毒感染组(Exp)和非感染对照组(Con)6 h和45 h的藻细胞样品进行转录组测序分析。共得到32909条平均长度为1153 bp的基因。病毒感染6 h和45 h分别得到2617和5229个差异表达基因,其中共差异表达基因465个。随机选取10条差异表达基因,采用qRT-PCR进行实验验证,结果证实转录组分析可靠。GO功能注释和KEGG通路富集,发现大量基因与氧化应激反应、脂类代谢、碳水化合物代谢及信号转导等代谢过程相关,其中变化最显著的是谷胱甘肽代谢途径。从病毒感染球石藻转录组中筛选出部分与氧化应激反应相关的基因,其中9个基因显著上调,11个基因显著下调,表明宿主能够通过体内的氧化应激反应响应病毒胁迫。

Emiliania huxleyi,the numerically dominant coccolithophore in the modern oceans and its specific lytic virus EhV exert a critical impact upon the oceanic carbon,sulfur cycle and global climate,thus serving as a key host-pathogen model system.Despite their impact on biogeochemical cycling,the transcriptional dynamics of these important oceanic events is still poorly understood.To understand the host-virus interaction in E.huxleyi-EhV system,the transcriptome of E.huxleyi BOF92 involved in virus infection was investigated by using Illumina HiSeq 2000 high-throughput sequencing technology.Two cDNA libraries,generated 6 h and 45 h after viral infection(Exp)were compared with two libraries from the corresponding times uninfected cultures(Con).A total of 32909 unigenes with an average length of 1153 bp were generated.Totally 2617 and 5229 differentially expressed genes(DEGs)associated with viral infection were identified in 6 hpi and 45 hpi,respectively,among which 465 genes were the common DEGs in the two time points.Ten DEGs were random selected for quantitative RT-PCR(qRTPCR)analysis,and the results confirmed that the transcriptome analysis was reliable.Furthermore,the DEGs were subject to GO and KEGG enrichment analysis.The results showed that most of the DEGs were involved in oxidation-reduction reactions,glutathione metabolism,lipid metabolism,carbohydrate metabolism and signal transduction.Some of the reactive oxygen species(ROS)scavenging genes were screened out,in which 9 genes were upregulated and 11 genes were down-regulated.These results suggested that ROS signaling molecules might play a central role during host-virus interaction.