BACKGROUND In Oman tobacco (Nicotiana tabacum; family Solanaceae) is a minor crop, which is produced only for local consumption. In 2015, tobacco plants exhibiting severe downward leaf curling, leaf thickening, vein swelling, yellowing and stunting were identified in fields of tobacco in Suhar Al-Batina region, Oman. These symptoms are suggestive of begomovirus (genus Begomovirus, family Geminiviridae) infection. METHODS Circular DNA molecules were amplified from total DNA extracted from tobacco plants by rolling circle amplification (RCA). Viral genomes were cloned from RCA products by restriction digestion and betasatellites were cloned by PCR amplification from RCA product, using universal primers. The sequences of full-length clones were obtained by Sanger sequencing and primer walking. Constructs for the infectivity of virus and betasatellite were produced and introduced into plants by Agrobacterium-mediated inoculation. RESULTS The full-length sequences of 3 begomovirus and 3 betasatellite clones, isolated from 3 plants, were obtained. Analysis of the full-length sequences determined showed the virus to be a variant of Chilli leaf curl virus (ChiLCV) and the betasatellite to be a variant of Tomato leaf curl betasatellite (ToLCB). Both the virus and the betasatellite isolated from tobacco show the greatest levels of sequence identity to isolates of ChiLCV and ToLCB identified in other hosts in Oman. Additionally clones of ChiLCV and ToLCB were shown, by Agrobacterium-mediated inoculation, to be infectious to 3 Nicotiana species, including N. tabacum. In N. benthamiana the betasatellite was shown to change the upward leaf rolling symptoms to a severe downward leaf curl, as is typical for many monopartite begomoviruses with betasatellites. CONCLUSIONS The leaf curl disease of tobacco in Oman was shown to be caused by ChiLCV and ToLCB. This is the first identification of ChiLCV with ToLCB infecting tobacco. The study shows that, despite the low diversity of begomoviruses and betasatellites in Oman, the extant viruses/betasatellites are able to fill the niches that present themselves.

中文翻译：

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感染阿曼烟草的辣椒卷叶病毒和相关番茄卷叶β卫星的分子和生物学特征。


背景技术在阿曼，烟草（Nicotiana tabacum；茄科）是一种次要作物，其生产仅供当地消费。 2015年，阿曼Suhar Al-Batina地区的烟田发现烟草植株表现出严重的叶片向下卷曲、叶片增厚、叶脉肿胀、黄化和发育迟缓的现象。这些症状提示 Begomovirus（双生病毒科 Begomovirus 属）感染。方法通过滚环扩增（RCA）从烟草植物中提取的总DNA中扩增环状DNA分子。通过限制性消化从 RCA 产物中克隆病毒基因组，并使用通用引物通过 PCR 扩增从 RCA 产物中克隆 β 卫星。通过Sanger测序和引物步移获得全长克隆的序列。产生病毒和β卫星感染性的构建体并通过农杆菌介导的接种引入植物中。结果从3株植物中分离得到3个begomovirus全长序列和3个β卫星克隆。对确定的全长序列的分析表明，该病毒是辣椒卷叶病毒（ChiLCV）的变种，而β卫星是番茄卷叶病毒（ToLCB）的变种。从烟草中分离出的病毒和 β 卫星与阿曼其他宿主中鉴定的 ChiLCV 和 ToLCB 分离株显示出最高水平的序列同一性。此外，通过农杆菌介导的接种，显示 ChiLCV 和 ToLCB 的克隆对 3 种烟草属物种具有感染性，包括烟草。在本塞姆氏烟草中，β卫星被证明可以将向上的卷叶症状改变为严重的向下卷叶，这对于许多带有β卫星的单分贝戈莫病毒来说是典型的。 结论 阿曼烟草卷叶病是由 ChiLCV 和 ToLCB 引起的。这是首次鉴定 ChiLCV 与感染烟草的 ToLCB。研究表明，尽管阿曼的贝戈莫病毒和贝塔卫星多样性较低，但现有的病毒/贝塔卫星能够填补现有的空白。