Dipartimento di Scienze del Suolo della Pianta e degli Alimenti, Università degli Studi di Bari Aldo Moro, Bari, Italy.
Istituto del CNR per la Protezione Sostenibile delle Piante, UOS di Bari, Bari, Italy.
Sci Rep. 2019 Feb 25;9(1):2657. doi: 10.1038/s41598-019-39162-w.
RNA interference (RNAi) is a sequence identity-dependent RNA degradation mechanism conserved in eukaryotic organisms. One of the roles of RNAi is as a defense system against viral infections, which has been demonstrated in filamentous fungi but not in oomycetes. We investigated the virus-RNAi interplay in the oomycete Phytophthora infestans using a crucifer-infecting strain of the plant virus tobacco mosaic virus (TMVcr) and its derivative TMVcr-Δ122 that is mutated in the sequence of the p122 replicase subunit and thus inhibited in RNA suppression activity. In this study we provide evidence that replication of TMVcr-Δ122 but not of TMVcr was impaired in P. infestans as well as in tobacco plants used as positive control. The interference was associated with induction of high transcription of dicer-like genes Pidcl2 and NtDCL2 and of RNA-dependent-RNA-polymerase Pirdr1 and NtRDR1 in P. infestans and tobacco, respectively. These high transcription levels suggest an RNAi-based response that TMVcr-Δ122 mutant was not able to suppress. Taken altogether, results of this study demonstrated that an antiviral silencing activity operates also in P. infestans and that a plant virus could be a simple and feasible tool for functional studies also in oomycetes.
RNA 干扰（RNAi）是一种在真核生物中保守的序列同源依赖性 RNA 降解机制。RNAi 的作用之一是作为抗病毒感染的防御系统，这在丝状真菌中得到了证实，但在卵菌中尚未得到证实。我们使用十字花科植物病毒烟草花叶病毒（TMVcr）的一种侵染甘蓝的菌株及其在 p122 复制酶亚基序列中发生突变的衍生物 TMVcr-Δ122 ，研究了卵菌致病疫霉中的病毒-RNAi 相互作用，因此其 RNA 抑制活性受到抑制。在这项研究中，我们提供的证据表明，TMVcr-Δ122 的复制在致病疫霉以及用作阳性对照的烟草植物中受到了抑制，而 TMVcr 的复制则没有受到抑制。这种干扰与 P. infestans 和烟草中二型 RNA 依赖性 RNA 聚合酶 Pirdr1 和 NtRDR1 以及 dicer-like 基因 Pidcl2 和 NtDCL2 的高转录诱导相关。这些高转录水平表明存在基于 RNAi 的反应，而 TMVcr-Δ122 突变体无法抑制这种反应。总的来说，这项研究的结果表明，抗病毒沉默活性也在致病疫霉中起作用，植物病毒也可以成为卵菌功能研究的简单可行工具。
