ndirect evidence of mitochondrial viruses in plants comes from discovery of genomic fragments integrated into the nuclear and mitochondrial DNA of a number of plant species. Here, we report the existence of replicating mitochondrial virus in plants: from RNAseq data of infected Chenopodium quinoa, a plant species commonly used as a test plant in virus host-range experiments, among other virus contigs, we could assemble a 2.7 Kb contig that had highest similarity to mitoviruses found in plant genomes. Northern blot analyses confirmed the existence of plus and minus strand RNA corresponding to the mitovirus genome. No DNA corresponding to the genomic RNA was detected, excluding the endogenization of such virus. We have tested a number of C. quinoa accessions, and the virus was present in a number of commercial varieties, but absent from a large collection of Bolivian and Peruvian accessions. The virus could not be transmitted mechanically or by grafting, but it is transmitted vertically through seeds at a 100% rate. Small RNA analysis of a C. quinoa line carrying the mitovirus and infected by alfalfa mosaic virus showed that the typical anti-viral silencing response active against cytoplasmic viruses (21-22 nt vsRNA peaks) is not active against CqMV1, since in this specific case the highest accumulating vsRNA length is 16, which is the same as that corresponding to RNA from mitochondrial genes. This is evidence of a distinct viral RNA degradation mechanism active inside mitochondria that could possibly have also an anti-viral effect.

Biological and molecular characterization of Chenopodium quinoa mitovirus 1 reveals a distinct sRNA response compared to cytoplasmic RNA viruses.

L. Nerva;G. Vigani;M. Ciuffo;W. Chitarra;
2019

Abstract

ndirect evidence of mitochondrial viruses in plants comes from discovery of genomic fragments integrated into the nuclear and mitochondrial DNA of a number of plant species. Here, we report the existence of replicating mitochondrial virus in plants: from RNAseq data of infected Chenopodium quinoa, a plant species commonly used as a test plant in virus host-range experiments, among other virus contigs, we could assemble a 2.7 Kb contig that had highest similarity to mitoviruses found in plant genomes. Northern blot analyses confirmed the existence of plus and minus strand RNA corresponding to the mitovirus genome. No DNA corresponding to the genomic RNA was detected, excluding the endogenization of such virus. We have tested a number of C. quinoa accessions, and the virus was present in a number of commercial varieties, but absent from a large collection of Bolivian and Peruvian accessions. The virus could not be transmitted mechanically or by grafting, but it is transmitted vertically through seeds at a 100% rate. Small RNA analysis of a C. quinoa line carrying the mitovirus and infected by alfalfa mosaic virus showed that the typical anti-viral silencing response active against cytoplasmic viruses (21-22 nt vsRNA peaks) is not active against CqMV1, since in this specific case the highest accumulating vsRNA length is 16, which is the same as that corresponding to RNA from mitochondrial genes. This is evidence of a distinct viral RNA degradation mechanism active inside mitochondria that could possibly have also an anti-viral effect.
JOURNAL OF VIROLOGY
1
34
https://jvi.asm.org/content/early/2019/01/10/JVI.01998-18
Virus, mitochondria, quinoa, mitovirus, defense, silencing, sRNA
L. Nerva, G. Vigani, D. Di Silvestre, M. Ciuffo, M. Forgia, W. Chitarra, M. Turina
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2318/1694939
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