Begomoviruses (family Geminiviridae) have a circular, ssDNA genome encapsidated in twinned icosahedral particles. Numerous begomoviruses infecting noncultivated malvaceous plants have been described, and evidence suggests that they may have given rise to some of the viruses currently found in crop plants. Here we describe an atypical begomovirus infecting ornamental Turk's hat plants (Malvaviscus arboreus, Malvaceae). Total DNA was extracted, and the viral genome was amplified by rolling-circle amplification (RCA), cloned and sequenced. Sequence and phylogenetic analyses indicated that the virus corresponds to a new begomovirus phylogenetically related to other malvaceous-infecting begomoviruses from Brazil, and for which the name malvaviscus yellow mosaic virus (MvYMV) is proposed. M. arboreus plants inoculated with MvYMV infectious clones showed bright yellow mosaic and the virus progeny was identical to the isolate inoculated, thus fulfilling Koch's postulates. Strikingly, MvYMV has a nanovirus/alphasatellite-like nonanucleotide sequence (5′-TAGTATTAC-3′). Moreover, a short sequence located 5′ of the nonanucleotide potentially forms a minor hairpin structure embedded in the major hairpin. Intramolecular interactions involving the sequence of the atypical hairpin structure were predicted and functional analyses were conducted to assess its biological relevance, revealing that the MvYMV Rep protein recognises this unique replication origin but not the typical begomovirus origin. Thus, MvYMV is a begomovirus with an atypical origin of replication and naturally found in noncultivated malvaceous plants.

中文翻译：

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Malvaviscus 黄色花叶病毒，一种带有纳米病毒样九核苷酸和修饰的茎环结构的发散豆豆病毒

Begomoviruses（Geminiviridae科）有一个圆形的 ssDNA 基因组，包裹在孪生二十面体颗粒中。已经描述了许多感染非栽培锦葵科植物的 begomovirus 病毒，并且有证据表明它们可能引起了目前在作物植物中发现的一些病毒。这里我们介绍一种非典型感染双生观赏土耳其人的帽子植物（悬铃花属arboreus，锦葵科）。提取总DNA，通过滚环扩增（RCA）对病毒基因组进行扩增、克隆和测序。序列和系统发育分析表明，该病毒对应于一种新的 Begomovirus，在系统发育上与来自巴西的其他感染锦葵科的 begomovirus 相关，并建议将其命名为 Malvaviscus Yellow 花叶病毒 (MvYMV)。用 MvYMV 感染性克隆接种的M. arboreus植株呈现亮黄色花叶，病毒后代与接种的分离株完全相同，符合 Koch 假设。引人注目的是，MvYMV 具有纳米病毒/α卫星样九核苷酸序列（5'-TAGTATTAC-3'）。此外，位于九核苷酸 5' 端的短序列可能形成嵌入主发夹中的小发夹结构。预测了涉及非典型发夹结构序列的分子内相互作用，并进行了功能分析以评估其生物学相关性，揭示 MvYMV Rep 蛋白识别这种独特的复制起点，但不识别典型的 begomovirus 起源。因此，MvYMV 是一种具有非典型复制起点的 begomovirus，天然存在于未栽培的锦葵科植物中。