Department of Plant Pathology, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Scottsville, Pietermaritzburg, South Africa.
Department of Rural Agronomy and Development, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Scottsville, Pietermaritzburg, South Africa.
PLoS One. 2019 Jul 24;14(7):e0220298. doi: 10.1371/journal.pone.0220298. eCollection 2019.
Criniviruses accumulate in the phloem tissue and damage crops by reducing chlorophyll which is essential for plant growth and development. Tomato chlorosis crinivirus (ToCV) is vectored by several whitefly species that damage tomato crops throughout the world. In South Africa, ToCV is a poorly studied pathogen of global economic importance. Therefore, a national survey was initiated to investigate the occurrence and distribution of criniviruses infecting tomato crops in South Africa. Whitefly infested tomato crops exhibiting interveinal leaf chlorosis and chlorotic flecking symptoms were assayed for crinivirus infections using a multiplex reverse transcription polymerase reaction (RT-PCR) approach to assess for the presence of crinivirus species that are known to infect solanaceous hosts. Next-generation sequencing (NGS) was used to generate the complete genome of ToCV from South Africa. Results from the survey indicated that ToCV is presently the only crinivirus species infecting tomatoes in South Africa. Blast analysis showed that the RNA-1 segment of ToCV from South Africa (ToCR1-186) matched 99% to Spanish isolates. On the other hand, the RNA-2 (ToCR2-186) segment matched 98% to a South Korean isolate and three Spanish isolates. Although recombination events were not detected, phylogenetic studies showed inconsistencies in the grouping of RNA-1 and RNA-2 segments for some of the ToCV isolates analyzed in this study. Therefore, we suggest the possibility of intraspecific reassortment. This is the first comprehensive study and full genome sequence of ToCV from South Africa. The information generated from this study is intended to raise awareness of ToCV infections on tomato crops in South Africa.
菜豆金色花叶病毒在韧皮部组织中积累，并通过减少叶绿素来损害作物，而叶绿素对植物生长和发育至关重要。番茄黄化曲叶病毒（ToCV）由几种粉虱传播，这些粉虱在世界各地都会损害番茄作物。在南非，ToCV 是一种研究不足但具有全球经济重要性的病原体。因此，发起了一项全国性调查，以研究感染南非番茄作物的菜豆金色花叶病毒的发生和分布情况。使用多重反转录聚合酶反应（RT-PCR）方法，对感染粉虱的出现叶脉间叶褪绿和斑驳褪绿症状的番茄作物进行菜豆金色花叶病毒感染检测，以评估已知感染茄科寄主的菜豆金色花叶病毒种的存在情况。下一代测序（NGS）用于从南非产生 ToCV 的完整基因组。调查结果表明，目前 ToCV 是南非唯一感染番茄的菜豆金色花叶病毒种。Blast 分析表明，南非 ToCV 的 RNA-1 片段（ToCR1-186）与西班牙分离株的匹配度为 99%。另一方面，RNA-2（ToCR2-186）片段与韩国分离株和三个西班牙分离株的匹配度为 98%。虽然未检测到重组事件，但系统发育研究表明，在本研究分析的一些 ToCV 分离株中，RNA-1 和 RNA-2 片段的分组存在不一致性。因此，我们建议存在种内重配的可能性。这是南非首次对 ToCV 进行全面研究和全基因组序列分析。本研究产生的信息旨在提高南非对番茄作物上 ToCV 感染的认识。
