Table_1_The Induction of an Effective dsRNA-Mediated Resistance Against Tomato Spotted Wilt Virus by Exogenous Application of Double-Stranded RNA Largely Depends on the Selection of the Viral RNA Target Region.DOCX

Tomato spotted wilt virus (TSWV) is a devastating plant pathogen, causing huge crop losses worldwide. Unfortunately, due to its wide host range and emergence of resistance breaking strains, its management is challenging. Up to now, resistance to TSWV infection based on RNA interference (RNAi) has been achieved only in transgenic plants expressing parts of the viral genome or artificial microRNAs targeting it. Exogenous application of double-stranded RNAs (dsRNAs) for inducing virus resistance in plants, namely RNAi-based vaccination, represents an attractive and promising alternative, already shown to be effective against different positive-sense RNA viruses and viroids. In the present study, the protection efficacy of exogenous application of dsRNAs targeting the nucleocapsid (N) or the movement protein (NSm) coding genes of the negative-sense RNA virus TSWV was evaluated in Nicotiana benthamiana as model plant and in tomato as economically important crop. Most of the plants treated with N-targeting dsRNAs, but not with NSm-targeting dsRNAs, remained asymptomatic until 40 (N. benthamiana) and 63 (tomato) dpi, while the remaining ones showed a significant delay in systemic symptoms appearance. The different efficacy of N- and NSm-targeting dsRNAs in protecting plants is discussed in the light of their processing, mobility and biological role. These results indicate that the RNAi-based vaccination is effective also against negative-sense RNA viruses but emphasize that the choice of the target viral sequence in designing RNAi-based vaccines is crucial for its success.

番茄斑萎病毒（Tomato spotted wilt virus, TSWV）是一种极具破坏性的植物病原物，在全球范围内造成巨额作物减产。遗憾的是，由于其寄主范围广泛且出现了突破抗病性的毒株，该病毒的防治颇具挑战。截至目前，基于RNA干扰（RNA interference, RNAi）的抗TSWV侵染策略仅在表达病毒基因组片段或靶向该病毒的人工微小RNA的转基因植株中得以实现。通过外源施用双链RNA（double-stranded RNAs, dsRNAs）来诱导植物产生病毒抗性，即基于RNAi的疫苗接种，是一种极具吸引力且颇具前景的替代方案，目前已被证实对多种正链RNA病毒和类病毒有效。本研究以模式植物本氏烟草（Nicotiana benthamiana）以及具有经济重要性的作物番茄为试材，评估了靶向负链RNA病毒TSWV核衣壳（nucleocapsid, N）或运动蛋白（movement protein, NSm）编码基因的外源dsRNAs的防护效果。多数经靶向N基因的dsRNAs处理的植株，而非经靶向NSm基因的dsRNAs处理的植株，在接种后40天（本氏烟草）和63天（番茄）时仍未表现出症状，其余植株则出现系统症状的时间显著延迟。研究针对靶向N和NSm基因的dsRNAs在防护植物效果上的差异，结合其加工过程、移动性及生物学功能展开了讨论。本研究结果表明，基于RNAi的疫苗接种策略对负链RNA病毒同样有效，同时也强调，在设计RNAi疫苗时，目标病毒序列的选择对其成功应用至关重要。