• Viruses cause severe damage on crops, and identification of key gene(s) that can comprehensively activate antiviral immunity will provide insights for designing effective antiviral strategies. Salicylic acid (SA)-mediated antiviral immunity and RNA interference (RNAi) are two independently discovered antiviral pathways. Previously, we identified the orchid stress-associated protein (SAP), Pha13, which serves as a hub in SA-mediated antiviral immunity. As SAPs exist as a protein family, whether duplicated SAPs have redundant or distinctive functions in antiviral immunity remains elusive.
• We performed functional assays on orchid Pha21, a homolog of Pha13, using transient and transgenic approaches on orchid, Arabidopsis and Nicotiana benthamiana to overexpress and/or silence Pha21.
• The SA treatment induced the expression of both Pha13 and Pha21, whereas Pha21 was found to play a key role in the initiation of the RNAi pathway in Phalaenopsis orchids. We demonstrated that Pha21-mediated antiviral immunity and enhancement of the RNAi pathway is conserved between dicotyledons and monocotyledons.
• We provide new insight that orchid SAPs confer distinctive functions to coordinate both SA-signaling and RNAi for comprehensive activation of antiviral immunity, and this information will help us develop antiviral strategies on crops.

中文翻译：

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应激相关蛋白协调蝴蝶兰综合抗病毒免疫的激活

• 病毒对农作物造成严重破坏，鉴定能够全面激活抗病毒免疫的关键基因将为设计有效的抗病毒策略提供参考。水杨酸 (SA) 介导的抗病毒免疫和 RNA 干扰 (RNAi) 是两个独立发现的抗病毒途径。以前，我们确定了兰花应激相关蛋白 (SAP) Pha13，它是 SA 介导的抗病毒免疫的中枢。由于 SAP 作为蛋白质家族存在，重复的 SAP 在抗病毒免疫中是否具有冗余或独特的功能仍然难以捉摸。
• 我们使用兰花、拟南芥和本氏烟草的瞬时和转基因方法对 Pha13 的同源物兰花 Pha21 进行了功能测定，以过度表达和/或沉默 Pha21。
• SA 处理诱导 Pha13 和 Pha21 的表达，而 Pha21 被发现在蝴蝶兰中RNAi 途径的启动中起关键作用。我们证明了 Pha21 介导的抗病毒免疫和 RNAi 途径的增强在双子叶植物和单子叶植物之间是保守的。
• 我们提供了新的见解，即兰花 SAP 赋予协调 SA 信号和 RNAi 以全面激活抗病毒免疫的独特功能，这些信息将帮助我们制定作物抗病毒策略。