• Phytophthora spp. cause serious damage to plants by exploiting a large number of effector proteins and small RNAs (sRNAs). Several reports have described modulation of host RNA biogenesis and defence gene expression. Here, we analysed Phytophthora infestans Argonaute (Ago) 1 associated small RNAs during potato leaf infection.
• Small RNAs were co-immunoprecipitated, deep sequenced and analysed against the P. infestans and potato genomes, followed by transcript analyses and transgenic assays on a predicted target.
• Extensive targeting of potato and pathogen-derived sRNAs to a range of mRNAs was observed, including 638 sequences coding for resistance (R) proteins in the host genome. The single miRNA encoded by P. infestans (miR8788) was found to target a potato alpha/beta hydrolase-type encoding gene (StABH1), a protein localized to the plasma membrane. Analyses of stable transgenic potato lines harbouring overexpressed StABH1 or artificial miRNA gene constructs demonstrated the importance of StABH1 during infection by P. infestans. miR8788 knock-down strains showed reduced growth on potato, and elevated StABH1 expression levels were observed when plants were inoculated with the two knock-down strains compared to the wild-type strain 88069.
• The findings of our study suggest that sRNA encoded by P. infestans can affect potato mRNA, thereby expanding our knowledge of the multifaceted strategies this species uses to facilitate infection.

中文翻译：

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致病疫霉Ago1相关miRNA促进马铃薯晚疫病

• 疫霉属 通过利用大量效应蛋白和小 RNA (sRNA) 对植物造成严重损害。一些报告描述了宿主 RNA 生物发生和防御基因表达的调节。在这里，我们分析了马铃薯叶片感染期间致病疫霉( Phytophthora infestans Argonaute) (Ago) 1 相关的小 RNA。
• 对小 RNA 进行免疫共沉淀、深度测序并针对P. infestans和马铃薯基因组进行分析，然后对预测的目标进行转录分析和转基因检测。
• 观察到马铃薯和病原体衍生的 sRNA 广泛靶向一系列 mRNA，包括宿主基因组中编码抗性 (R) 蛋白的 638 个序列。发现由致病疫霉(miR8788)编码的单个 miRNA靶向马铃薯 α/β 水解酶型编码基因 ( StABH1 )，这是一种定位于质膜的蛋白质。对含有过表达StABH1或人工 miRNA 基因构建体的稳定转基因马铃薯品系的分析证明了StABH1在致病疫霉感染期间的重要性。miR8788 敲低菌株在马铃薯上的生长减少，StABH1升高 与野生型菌株 88069 相比，当植物接种两种敲低菌株时，观察到表达水平。
• 我们的研究结果表明，致病疫霉编码的 sRNA可以影响马铃薯 mRNA，从而扩大了我们对该物种用于促进感染的多方面策略的了解。