中文摘要：RNA沉默是植物体内一种重要的天然抗病毒防御机制。RNA依赖的RNA聚合酶（RDRs）可促进双链RNAs的合成，被认为是RNA沉默途径的基本要素。在拟南芥中，RDR1、2和6在抗病毒RNA沉默中起着重要的作用。RDR1的表达可通过随后对植物进行防御激素和病毒感染处理来提高。RDR1在有些作物上已经有研究，但是在辣椒上的研究还没有。本研究从辣椒上分离得到一个RDR1基因，命名为CaRDR1。研究结果表明，CaRDR1通过调节抗氧化酶活性和RNA沉默相关基因的表达来抑制烟草花叶病毒（TMV）的复制和移动，在TMV防御中起着积极的作用。
外文摘要：RNA silencing functions as a major natural antiviral defense mechanism in plants. RNA-dependent RNA polymerases (RDRs) that catalyze the synthesis of double-stranded RNAs, are considered as a fundamental element in RNA silencing pathways. In Arabidopsis thaliana, RDR1, 2 and 6 play important roles in anti-viral RNA silencing. Expression of RDR1 can be elevated following plant treatment with defense hormones and virus infection. RDR1 has been studied in several crop species, but not in pepper (Capsicum annuum L.). Here, a RDR1 gene was isolated from Capsicum annuum L., designated as CaRDR1. The full-length cDNA of CaRDR1 was 3,351 bp, encoding a 1,116-amino acid protein, which contains conserved regions, such as the most remarkable motif DLDGD. The transcripts of CaRDR1 could be induced by salicylic acid (SA), abscisic acid (ABA), H2O2, and tobacco mosaic virus (TMV). Silencing of CaRDR1 in pepper resulted in increased susceptibility to TMV as evident by severe symptom, increased of TMV-CP transcript, higher malondialdehyde (MDA) content and lower antioxidant enzymes activities compared with that of control plants. CaRDR1-overexpressing in Nicotiana benthamiana showed mild disease symptom and reduced TMV-CP transcripts than that of empty vector (EV) following TMV inoculation. The RNA silencing related genes, including NbAGO2, NbDCL2, NbDCL3, and NbDCL4 elevated expression in overexpressed plants. Alternative oxidase (AOX), the terminal oxidase of the cyanide (CN)-resistant alternative respiratory pathway, catalyze oxygen-dependent oxidation of ubiquinol in plants. It has an important function in plant defense against TMV. In addition, CaRDR1 overexpression promoted the expression of NbAOX1a and NbAOX1b. In conclusion, these results suggest that CaRDR1 plays a positive role in TMV resistance by regulating antioxidant enzymes activities and RNA silencing-related genes expression to suppress the replication and movement of TMV.
外文关键词：pepper, CaRDR1, tobacco mosaic virus (TMV), resistance, Nicotiana benthamiana
作者：Qin, Lei; Mo, Ning; Zhang, Yang; 等
作者单位：西北农林科技大学
期刊名称：FRONTIERS IN PLANT SCIENCE
期刊影响因子：4.298
出版年份：2017
出版刊次：6
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