Salicylic acid treatment and expression of an RNA-dependent RNA polymerase 1 transgene inhibit lethal symptoms and meristem invasion during tobacco mosaic virus infection in Nicotiana benthamiana.
Salicylic acid treatment and expression of an RNA-dependent RNA polymerase 1 transgene inhibit lethal symptoms and meristem invasion during tobacco mosaic virus infection in Nicotiana benthamiana.
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DOI：
10.1186/s12870-016-0705-8
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发表时间：
2016-01-13
影响因子：
5.3
通讯作者：
Carr JP
中科院分区：
文献类型：
--
作者：
Lee WS;Fu SF;Li Z;Murphy AM;Dobson EA;Garland L;Chaluvadi SR;Lewsey MG;Nelson RS;Carr JP
宿主RNA依赖RNA聚合酶（RDRs） 1和6参与植物抗病毒RNA沉默。RDR6是组成性表达的，以前的研究表明，RDR6可以限制马铃薯病毒X对本烟分生组织的入侵，从而抑制疾病的发展。RDR1可被水杨酸（SA）和其他几种植物激素诱导。但是，虽然它有助于烟草花叶病毒（TMV）的基础抗性，但它对接种叶片的sa诱导抗性是必不可少的。benthamiana实验室菌株是一种天然的rdr1突变体，对TMV高度敏感。然而，在表达苜蓿RDR1的转基因植物中，tmv诱导的症状得到了改善。在转mtrdr1基因的benthamiana植物中，表达绿色荧光蛋白（TMV. gfp）的TMV在上部未接种的叶片中传播不受抑制。然而，在这些植物中排除了TMV。来自顶端分生组织和邻近茎组织的GFP高于对照植株，SA增强了这种排斥作用。TMV通常会杀死N. benthamiana植物，但尽管mtrdr1转基因植物最初表现出病毒诱导的坏死，但它们随后会恢复。在mtrdr1转基因植株中，SA处理显著促进了病害的恢复，而在对照植株中，SA延迟但不阻止系统性坏死和死亡。MtRDR1转基因植株经SA处理后，可提取的RDR酶活性增加，Western blot分析发现RDR提取物与MtRDR1抗体有条带交叉反应。MtRDR1在转基因benthamiana植物中的表达是由花椰菜花叶病毒衍生的组成型35S启动子驱动的，证实该启动子对SA无反应。这表明SA对MtRDR1的影响是在转录后水平上发挥的。MtRDR1通过限制病毒向受感染植物生长尖端的传播来抑制严重症状的发展。因此，RDR1可能以类似于RDR6的方式起作用。MtRDR1和SA共同作用，进一步促进转基因MtRDR1植株的疾病症状恢复。因此，SA可能通过转录后效应促进MtRDR1活性和/或稳定性。本文的在线版本（doi:10.1186/s12870-016-0705-8）包含补充材料，仅供授权用户使用。
Host RNA-dependent RNA polymerases (RDRs) 1 and 6 contribute to antiviral RNA silencing in plants. RDR6 is constitutively expressed and was previously shown to limit invasion of Nicotiana benthamiana meristem tissue by potato virus X and thereby inhibit disease development. RDR1 is inducible by salicylic acid (SA) and several other phytohormones. But although it contributes to basal resistance to tobacco mosaic virus (TMV) it is dispensable for SA-induced resistance in inoculated leaves. The laboratory accession of N. benthamiana is a natural rdr1 mutant and highly susceptible to TMV. However, TMV-induced symptoms are ameliorated in transgenic plants expressing Medicago truncatula RDR1. In MtRDR1-transgenic N. benthamiana plants the spread of TMV expressing the green fluorescent protein (TMV.GFP) into upper, non-inoculated, leaves was not inhibited. However, in these plants exclusion of TMV.GFP from the apical meristem and adjacent stem tissue was greater than in control plants and this exclusion effect was enhanced by SA. TMV normally kills N. benthamiana plants but although MtRDR1-transgenic plants initially displayed virus-induced necrosis they subsequently recovered. Recovery from disease was markedly enhanced by SA treatment in MtRDR1-transgenic plants whereas in control plants SA delayed but did not prevent systemic necrosis and death. Following SA treatment of MtRDR1-transgenic plants, extractable RDR enzyme activity was increased and Western blot analysis of RDR extracts revealed a band cross-reacting with an antibody raised against MtRDR1. Expression of MtRDR1 in the transgenic N. benthamiana plants was driven by a constitutive 35S promoter derived from cauliflower mosaic virus, confirmed to be non-responsive to SA. This suggests that the effects of SA on MtRDR1 are exerted at a post-transcriptional level. MtRDR1 inhibits severe symptom development by limiting spread of virus into the growing tips of infected plants. Thus, RDR1 may act in a similar fashion to RDR6. MtRDR1 and SA acted additively to further promote recovery from disease symptoms in MtRDR1-transgenic plants. Thus it is possible that SA promotes MtRDR1 activity and/or stability through post-transcriptional effects. The online version of this article (doi:10.1186/s12870-016-0705-8) contains supplementary material, which is available to authorized users.