College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Ministry of Education, Nanjing 210095, China.
Plant Physiol. 2018 May;177(1):352-368. doi: 10.1104/pp.17.01665. Epub 2018 Mar 16.
MicroRNAs play crucial roles in plant responses to pathogen infections. The rice blast disease, caused by the fungus , is the most important disease of rice (). To explore the microRNA species that participate in rice immunity against the rice blast disease, we compared the expression of small RNAs between mock- and -treated rice. We found that infection by strain Guy11 specifically induced the expression of rice miR319 and, consequently, suppressed its target gene (), which encodes a transcription factor. Using transgenic rice that overexpresses miR319b (OE) or expresses -Res (which is resistant to miR319-mediated silencing), we found that is a positive regulator of the rice defense response against the blast disease. When wild-type and miR319b-OE rice were infected by Guy11, multiple jasmonic acid (JA) synthetic and signaling components were suppressed, indicating that Guy11 suppresses JA signaling through inducing miR319. In particular, we found that () and were specifically suppressed by miR319 overexpression or by Guy11 infection. LOXs are the key enzymes of JA synthesis, which catalyze the conversion of α-linoleic acid to hydroperoxy-octadecadienoic acid. The application of α-linoleic acid rescued disease symptoms on the -Res rice but not wild-type rice, supporting our hypothesis that and are the key JA synthesis genes hijacked by Guy11 to subvert host immunity and facilitate pathogenicity. We propose that induced expression of may improve resistance to the rice blast disease.
MicroRNAs 在植物应对病原体感染的过程中发挥着至关重要的作用。稻瘟病是由真菌引起的，是水稻最重要的病害之一。为了探索参与水稻对稻瘟病免疫的 microRNA 种类，我们比较了模拟处理和处理后的水稻中小 RNA 的表达。我们发现，菌株 Guy11 的感染特异性诱导了水稻 miR319 的表达，进而抑制了其靶基因 ()的表达，该基因编码一个转录因子。利用过表达 miR319b 的转基因水稻（OE）或表达 -Res（对 miR319 介导的沉默具有抗性）的水稻，我们发现 是水稻对稻瘟病防御反应的正调控因子。当野生型和 miR319b-OE 水稻被 Guy11 感染时，多种茉莉酸（JA）合成和信号成分被抑制，表明 Guy11 通过诱导 miR319 抑制 JA 信号。特别是，我们发现 ()和 被 miR319 过表达或 Guy11 感染特异性抑制。LOXs 是 JA 合成的关键酶，它催化α-亚麻酸向羟基十八碳二烯酸的转化。α-亚麻酸的应用挽救了 -Res 水稻而不是野生型水稻上的疾病症状，支持我们的假设，即 和 是 Guy11 劫持的关键 JA 合成基因，以颠覆宿主免疫并促进致病性。我们提出，诱导表达 可能会提高对稻瘟病的抗性。
