National Centre for Biological Sciences (NCBS), Tata Institute of Fundamental Research (TIFR), GKVK campus, Bengaluru 560065, Karnataka, India.
Proc Biol Sci. 2020 Oct 14;287(1936):20201846. doi: 10.1098/rspb.2020.1846.
The genome of the plant-infecting viruses in the family Geminiviridae is composed of one or two circular single stranded DNA of approximately 2.7-5.2 kb in length. These viruses have emerged as the most devastating pathogen infecting a large number of crops and weeds across the continents. They code for fewer open reading frames (ORFs) through the generation of overlapping transcripts derived from the bidirectional viral promoters. Members of geminiviruses code for up to four ORFs in the virion-sense strand, and their gene expression is regulated by various -elements located at their promoters in the intergenic region. These viral proteins perform multiple functions at every stage of the viral life cycle such as virus transport, insect-mediated virus transmission and suppression of host defence. They impede the host's multi-layered antiviral mechanisms including gene silencing (at transcriptional and post-transcriptional levels) and hypersensitive response. This review summarizes the essential role of virion-sense strand encoded proteins in transport of viral genomes within and between plant cells, countering defence in hosts (both plants and the insects), and also in the ubiquitous role in vector-mediated transmission. We highlight the significance of their pro-viral activities in manipulating host-derived innate immune responses and the interaction with whitefly-derived proteins. We also discuss the current knowledge on virus replication and transcription within the insect body.
双生病毒科的植物病毒基因组由一条或两条约 2.7-5.2kb 长的环状单链 DNA 组成。这些病毒已成为感染各大洲大量作物和杂草的最具破坏性的病原体。它们通过来自双向病毒启动子的重叠转录本的产生，编码较少的开放阅读框 (ORF)。双生病毒在病毒 sense 链上最多编码四个 ORF，其基因表达受位于基因间区启动子上的各种 - 元件调控。这些病毒蛋白在病毒生命周期的每个阶段都执行多种功能，如病毒运输、昆虫介导的病毒传播和宿主防御抑制。它们阻碍宿主的多层次抗病毒机制，包括基因沉默（转录和转录后水平）和过敏反应。本综述总结了病毒 sense 链编码蛋白在病毒基因组在植物细胞内和细胞间的运输、对抗宿主防御（植物和昆虫）以及在媒介传播中的普遍作用中的重要作用。我们强调了它们在操纵宿主来源的先天免疫反应以及与粉虱来源的蛋白相互作用方面的促病毒活性的重要性。我们还讨论了关于昆虫体内病毒复制和转录的现有知识。
