Genomic variations in the 3′‐termini of Rice stripe virus in the rotation between vector insect and host plant

Abstract

Summary A large number of plant RNA viruses circulate between plants and insects. For RNA viruses, host alternations may impose a differential selective pressure on viral populations and induce variations in viral genomes. Here, we report the variations in the 3′‐terminal regions of the multiple‐segment RNA virus Rice stripe virus (RSV) that were discovered through de novo assembly of the genome using RNA sequencing data from infected host plants and vector insects.The newly assembled RSV genome contained 16‐ and 15‐nt extensions at the 3′‐termini of two genome segments compared with the published reference RSV genome. Our study demonstrated that these extensional sequences were consistently observed in two RSV isolates belonging to distinct genetic subtypes in RSV‐infected rice, wheat and tobacco. Moreover, the de novo assembled genome of Southern rice black‐streaked dwarf virus also contained 3′‐terminal extensions in five RNA segments compared with the reference genome.Time course experiments confirmed that the 3′‐terminal extensions of RSV were enriched in the vector insects, were gradually eliminated in the host plant and potentially affected viral replication.These findings indicate that variations in the 3′‐termini of viral genomes may be different adaptive strategies for plant RNA viruses in insects and plants.

The nucleocapsid protein of rice stripe virus in cell nuclei of vector insect regulates viral replication

“…Such different roles of viral nuclear entry in host and vector cells probably related to the different performances of viruses in the two organisms. Viruses must limit replication to maintain a perfect balance between viral load and the immunity pressure in vector cells for efficient transmission, while viruses exhibit excessive replication after countering the immune system in host cells (Blanc and Gutierrez, 2015 ; Zhao et al, 2016a ; Zhao et al, 2018 ; Zhao et al, 2019 ). This phenomenon is one of causes for insect-transmitted viruses typically being able to induce serious diseases in hosts but not in vector insects.…”

“…RSV is a typical persistent-propagative phytovirus that is efficiently transmitted by the small brown planthopper Laodelphax striatellus . Although it replicates and assembles in the cytoplasm of both planthopper and rice cells, RSV performs differently when living in the two organisms, exhibiting different pathogenicities (Zhao et al, 2016a ), replication and gene expression levels (Zhao et al, 2019 ), genomic 3′-termini (Zhao et al, 2018 ), and virus-derived siRNAs (Yang et al, 2018 ).…”

Evolution of plant–virus interactions: host range and virus emergence

“…The study of across-host fitness trade-offs and how they affect transmission across host species form an active field that has provided abundant evidence of penalties associated with the capacity to infect and multiply efficiently in a new host, expressed as reduced fitness in the original host [1,6]. Interestingly, trade-offs may also occur between the two different hosts, in which the virus must replicate to complete its life cycle, as in the plant host and insect vector of rice stripe virus [10]. Two major mechanisms causing across-host fitness trade-offs that have been extensively analysed are antagonistic pleiotropy [11] of host-range mutations and epistatic interactions among them [12].…”

Triazophos‐induced vertical transmission of rice stripe virus is associated with host vitellogenin in the small brown planthopper Laodelphax striatellus

“…RNA1 is negative‐sense to encode RNA‐dependent RNA polymerase. RNA2, RNA3 and RNA4 are ambisense, encoding NS2 (an RNA‐silencing suppressor) and NSvc2 (a putative membrane glycoprotein), NS3 (a suppressor of gene silencing) and CP (a capsid protein), SP (a disease‐specific protein) and NSvc4 (a movement protein), respectively …”

“…RNA2, RNA3 and RNA4 are ambisense, encoding NS2 (an RNAsilencing suppressor) and NSvc2 (a putative membrane glycoprotein), NS3 (a suppressor of gene silencing) and CP (a capsid protein), SP (a disease-specific protein) and NSvc4 (a movement protein), respectively. [14][15][16] Triazophos is a broad-spectrum organophosphorus insecticide widely used in Asia. 17 Insecticides degrade via photolysis and hydrolysis in the field, thereby insect pests prolonged exposure to different sublethal concentrations of insecticides.…”