Differential mRNA Accumulation upon Early Arabidopsis thaliana Infection with ORMV and TMV-Cg Is Associated with Distinct Endogenous Small RNAs Level

Small RNAs (sRNAs) play important roles in plant development and host-pathogen interactions. Several studies have highlighted the relationship between viral infections, endogenous sRNA accumulation and transcriptional changes associated with symptoms. However, few studies have described a global analysis of endogenous sRNAs by comparing related viruses at early stages of infection, especially before viral accumulation reaches systemic tissues. An sRNA high-throughput sequencing of Arabidopsis thaliana leaf samples infected either with Oilseed rape mosaic virus (ORMV) or crucifer-infecting Tobacco mosaic virus (TMV-Cg) with slightly different symptomatology at two early stages of infection (2 and 4dpi) was performed. At early stages, both viral infections strongly alter the patterns of several types of endogenous sRNA species in distal tissues with no virus accumulation suggesting a systemic signaling process foregoing to virus spread. A correlation between sRNAs derived from protein coding genes and the associated mRNA transcripts was also detected, indicating that an unknown recursive mechanism is involved in a regulatory circuit encompassing this sRNA/mRNA equilibrium. This work represents the initial step in uncovering how differential accumulation of endogenous sRNAs contributes to explain the massive alteration of the transcriptome associated with plant-virus interactions.

小分子RNA（sRNAs）在植物发育和宿主-病原体相互作用中扮演着至关重要的角色。众多研究已经强调了病毒感染、内源sRNA的积累以及与症状相关的转录变化之间的关系。然而，仅有少数研究对感染早期阶段（尤其是病毒积累达到系统性组织之前）的相关病毒进行了全局分析。对拟南芥（Arabidopsis thaliana）叶片样本进行sRNA高通量测序，这些样本分别感染了油菜花斑驳病毒（ORMV）或芸苔感染烟草花叶病毒（TMV-Cg），在感染的两个早期阶段（2天和4天）呈现出略微不同的症状。在感染早期，两种病毒感染均显著改变了远端组织中多种类型内源sRNA种类的模式，且未检测到病毒积累，这表明存在一种先于病毒传播的系统信号过程。同时，还发现源自蛋白质编码基因的sRNA与其相关的mRNA转录本之间存在相关性，这表明在调节涉及该sRNA/mRNA平衡的回路中，存在一种未知的递归机制。本研究初步揭示了内源sRNA差异积累如何有助于解释植物-病毒相互作用中转录组发生的巨大变化。