Virology Lab, Center for Agricultural Biochemistry and Biotechnology, University of Agriculture, Faisalabad, 38000, Pakistan.
Present address: Boyce Thompson Institute, Ithaca, NY, 14853, USA.
Virol J. 2018 Aug 31;15(1):134. doi: 10.1186/s12985-018-1047-y.
Geminiviruses cause major losses to several economically important crops. Pedilanthus leaf curl virus (PeLCV) is a pathogenic geminivirus that appeared in the last decade and is continuously increasing its host range in Pakistan and India. This study reports the identification and characterization of PeLCV-Petunia from ornamental plants in Pakistan, as well as geographical, phylogenetic, and recombination analysis.
Viral genomes and associated satellites were amplified, cloned, and sequenced from Petunia atkinsiana plants showing typical geminivirus infection symptoms. Virus-satellite complex was analyzed for phylogenetic and recombination pattern. Infectious clones of isolated virus and satellite molecules were constructed using a partial dimer strategy. Infectivity analysis of PeLCV alone and in combination with Digera yellow vein betasatellite (DiYVB) was performed by Agrobacterium infiltration of Nicotiana benthamiana and Petunia atkinsiana plants with infectious clones.
PeLCV, in association with DiYVB, was identified as the cause of leaf curl disease on P. atkinsiana plants. Sequence analysis showed that the isolated PeLCV is 96-98% identical to PeLCV from soybean, and DiYVB has 91% identity to a betasatellite identified from rose. Infectivity analysis of PeLCV alone and in combination with DiYVB, performed by Agrobacterium infiltration of infectious clones in N. benthamiana and P. atkinsiana plants, resulted in mild and severe disease symptoms 14 days after infiltration, respectively, demonstrating that these viruses are natural disease-causing agents. Southern blot hybridization indicated successful replication of the virus-betasatellite complex in the infected plants. Phylogenetic analysis suggests that PeLCV originated from Pakistan and later spread to India. Recombination analysis predicted that PeLCV is a donor parent for recombination and evolution of two important begomoviruses, Papaya leaf curl virus (PaLCuV) and Radish leaf curl virus (RaLCuV). The molecular phylogeny of genes encoding coat protein (CP) and replication associated protein (Rep) depict a complex evolutionary pattern of the viruses, with wide diversity in both of the genes.
This study presents PeLCV and DiYVB as a new natural combination resulting in leaf curl disease on P. atkinsiana plants. Phylogenetic analysis, in addition to recent agricultural reports, identify PeLCV as an emerging broad host range Begomovirus that is resident in Pakistan and, more recently, has also spread to India. Recombination analysis showed that PeLCV was involved in a natural recombinational event leading to the evolution of two recombinant begomoviruses, RaLCuV and PaLCuV.
双生病毒会给许多经济上重要的作物造成重大损失。豆薯曲叶病毒（PeLCV）是一种在过去十年中出现的致病性双生病毒，其宿主范围在巴基斯坦和印度不断扩大。本研究报告了在巴基斯坦观赏植物中发现的 PeLCV-Petunia 的鉴定和特征描述，以及地理、系统发育和重组分析。
从表现出典型双生病毒感染症状的矮牵牛植株中扩增、克隆和测序了病毒基因组及其相关卫星。分析了病毒-卫星复合物的系统发育和重组模式。使用部分二聚体策略构建了分离病毒和卫星分子的感染性克隆。通过将感染性克隆的农杆菌浸润到本氏烟和矮牵牛植物中，单独和组合地分析了 PeLCV 与 Digera 黄脉贝塔卫星（DiYVB）的感染性。
鉴定出与 DiYVB 相关的 PeLCV 是矮牵牛叶片卷曲病的致病因子。序列分析表明，分离出的 PeLCV 与大豆中的 PeLCV 具有 96-98%的同一性，而 DiYVB 与从玫瑰中鉴定出的贝塔卫星具有 91%的同一性。通过将感染性克隆的农杆菌浸润到本氏烟和矮牵牛植物中，单独和组合地分析了 PeLCV 的感染性，结果表明，在侵染后 14 天，分别出现了温和和严重的病症，这表明这些病毒是天然的致病因子。Southern blot 杂交表明，病毒-贝塔卫星复合物在感染植物中成功复制。系统发育分析表明，PeLCV 起源于巴基斯坦，后来传播到印度。重组分析预测，PeLCV 是两个重要的番茄曲叶病毒（PaLCuV）和萝卜曲叶病毒（RaLCuV）重组和进化的供体亲本。编码外壳蛋白（CP）和复制相关蛋白（Rep）的基因的分子系统发育描绘了病毒的复杂进化模式，这两个基因都具有广泛的多样性。
本研究提出 PeLCV 和 DiYVB 是导致矮牵牛植物叶片卷曲病的新的天然组合。除了最近的农业报道外，系统发育分析还将 PeLCV 鉴定为一种新兴的广泛宿主范围的双生病毒，它存在于巴基斯坦，最近也传播到了印度。重组分析表明，PeLCV 参与了导致两种重组双生病毒 RaLCuV 和 PaLCuV 进化的自然重组事件。
