Hubei Key Laboratory of Germplasm Innovation and Utilization of Fruit Trees, Research Institute of Fruit and Tea, Hubei Academy of Agricultural Sciences, Wuhan, 430064, Hubei, People's Republic of China.
Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, Jiangsu, People's Republic of China.
Virol J. 2024 Oct 16;21(1):256. doi: 10.1186/s12985-024-02508-6.
A major antiviral mechanism in plants is mediated by RNA silencing through the action of DICER-like (DCL) proteins, which cleave dsRNA into discrete small RNA fragments, and ARGONAUTE (AGO) proteins, which use the small RNAs to target single-stranded RNA. RNA silencing can also be amplified through the action of RNA-dependent RNA polymerases (RDRs), which use single stranded RNA to generate dsRNA that in turn is targeted by DCL proteins. As a counter-defense, plant viruses encode viral suppressors of RNA silencing (VSRs) that target different components in the RNA silencing pathway. The tomato Ty-1 gene confers resistance to the DNA virus tomato yellow leaf curl virus (TYLCV) and has been reported to encode an RDRγ protein. However, the molecular mechanisms by which Ty-1 controls TYLCV infection, including whether Ty-1 is involved in RNA silencing, are unknown. Here, by using a transient expression assay, we have confirmed that Ty-1 shows antiviral activity against TYLCV in Nicotiana benthamiana. Also, in transient expression-based silencing assays, Ty-1 augmented systemic transgene silencing in GFP transgenic N. benthamiana plants. Furthermore, co-expression of Ty-1 or other RDRγ proteins from N. benthamiana or Arabidopsis with various proteins resulted in lower protein expression. These results are consistent with a model wherein Ty-1-mediated resistance to TYLCV is due, at least in part, to an increase in RNA silencing activity.
植物中的一种主要抗病毒机制是通过 DICER 样（DCL）蛋白介导的 RNA 沉默来实现的，DCL 蛋白将双链 RNA 切割成离散的小 RNA 片段，ARGO 蛋白则利用这些小 RNA 靶向单链 RNA。RNA 沉默也可以通过 RNA 依赖性 RNA 聚合酶（RDR）的作用来放大，RDR 利用单链 RNA 生成双链 RNA，双链 RNA 又被 DCL 蛋白靶向。作为一种反防御机制，植物病毒编码 RNA 沉默的病毒抑制剂（VSR），靶向 RNA 沉默途径中的不同成分。番茄 Ty-1 基因赋予了对 DNA 病毒番茄黄卷叶病毒（TYLCV）的抗性，据报道它编码一种 RDRγ 蛋白。然而，Ty-1 控制 TYLCV 感染的分子机制，包括 Ty-1 是否参与 RNA 沉默，目前尚不清楚。在这里，我们通过瞬时表达分析证实，Ty-1 在本氏烟中对 TYLCV 表现出抗病毒活性。此外，在基于瞬时表达的沉默分析中，Ty-1 增强了 GFP 转基因本氏烟植物中的系统转基因沉默。此外，Ty-1 或来自本氏烟或拟南芥的其他 RDRγ 蛋白与各种蛋白的共表达导致蛋白表达水平降低。这些结果与一个模型一致，即 Ty-1 介导的对 TYLCV 的抗性至少部分归因于 RNA 沉默活性的增加。
