• Viral infections are accompanied by a massive production of small interfering RNAs (siRNAs) of plant origin, such as virus‐activated (va)siRNAs, which drive the widespread silencing of host gene expression, and whose effects in plant pathogen interactions remain unknown.
• By combining phenotyping and molecular analyses, we characterized vasiRNAs that are associated with typical mosaic symptoms of cauliflower mosaic virus infection in two crops, turnip (Brassica rapa) and oilseed rape (Brassica napus), and the reference plant Arabidopsis thaliana.
• We identified 15 loci in the three infected plant species, whose transcripts originate vasiRNAs. These loci appear to be generally affected by virus infections in Brassicaceae and encode factors that are centrally involved in photosynthesis and stress response, such as Rubisco activase (RCA), senescence‐associated protein, heat shock protein HSP70, light harvesting complex, and membrane‐related protein CP5. During infection, the expression of these factors is significantly downregulated, suggesting that their silencing is a central component of the plant’s response to virus infections. Further findings indicate an important role for 22 nt long vasiRNAs in the plant’s endogenous RNA silencing response.
• Our study considerably enhances knowledge about the new class of vasiRNAs that are triggered in virus‐infected plants and will help to advance strategies for the engineering of gene clusters involved in the development of crop diseases.

中文翻译：

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病毒感染的十字花科作物中的内源性激活 siRNA 显示出影响光合作用和应激反应的共同宿主基因沉默模式。

• 病毒感染伴随着植物来源的小干扰 RNA (siRNA) 的大量产生，例如病毒激活的 (va)siRNA，它们驱动宿主基因表达的广泛沉默，其对植物病原体相互作用的影响仍然未知。
• 通过结合表型分析和分子分析，我们表征了与两种作物萝卜 ( Brassica rapa ) 和油菜 ( Brassica napus ) 以及参考植物拟南芥中花椰菜花叶病毒感染的典型花叶症状相关的 vasiRNA 。
• 我们在三种受感染的植物物种中鉴定了 15 个基因座，其转录本源自 vasiRNA。这些基因座似乎通常受到十字花科病毒感染的影响，并编码与光合作用和应激反应有关的因子，例如 Rubisco 激活酶 (RCA)、衰老相关蛋白、热休克蛋白 HSP70、光捕获复合物和膜-相关蛋白 CP5。在感染期间，这些因子的表达显着下调，这表明它们的沉默是植物对病毒感染作出反应的核心组成部分。进一步的研究结果表明 22 nt 长的 vasiRNA 在植物内源性 RNA 沉默反应中的重要作用。
• 我们的研究大大增强了对病毒感染植物中触发的新型 vasiRNA 的认识，并将有助于推进参与作物病害发展的基因簇工程的策略。