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ARS Home » Plains Area » Lincoln, Nebraska » Wheat, Sorghum and Forage Research » Research » Publications at this Location » Publication #368232
Research Project: Improved Winter Wheat Disease Resistance and Quality through Molecular Biology, Genetics, and Breeding

Location: Wheat, Sorghum and Forage Research

Title: P7 and P8 proteins of High Plains wheat mosaic virus, a negative-strand RNA virus, utilize distinct mechanisms for suppression of RNA silencing

Author
item GUPTA, ADARSH - University Of Nebraska
item HEIN, GARY - University Of Nebraska
item Tatineni, Satyanarayana - Ts

Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2019
Publication Date: 7/1/2019
Citation: Gupta, A.K., Hein, G.L., Tatineni, S. 2019. P7 and P8 proteins of High Plains wheat mosaic virus, a negative-strand RNA virus, utilize distinct mechanisms for suppression of RNA silencing. Virology. 535:20-31. https://doi.org/10.1016/j.virol.2019.06.011.
DOI: https://doi.org/10.1016/j.virol.2019.06.011

Interpretive Summary: High Plains Wheat mosaic virus causes economically important diseases in wheat and maize in the Great Plains. The High Plains virus contains an RNA genome that encodes eight proteins. The P7 and P8 proteins encoded by RNA 7 and 8, respectively, suppressed RNA silencing. However, the mechanisms of these proteins in suppressing host RNA silencing are not known. Multiple virus-host interactions cause viral infections. Understanding the key strategies viruses use to overcome the natural defenses in plants could lead to the development of novel strategies for the management of economically important viral diseases. This research found that the two suppressors of RNA silencing proteins have distinct pathways to suppress the host defense mechanisms. This research also revealed that the P7 and P8 genes as primary targets for developing future molecular-based methods for managing High Plains disease.

Technical Abstract: High Plains wheat mosaic virus (genus Emaravirus), an octapartite negative-sense RNA virus, encodes two RNA silencing suppressors, P7 and P8. In this study, we found that P7 and P8 efficiently delayed the onset of dsRNA-induced transitive pathway of RNA silencing. Electrophoretic mobility shift assays (EMSA) revealed that only P7 protected long dsRNAs from dicing in vitro and bound weakly to 21- and 24-nt PTGS-like ds-siRNAs. In contrast, P8 bound strongly and relatively weakly to 21- and 24-nt ds-siRNAs, respectively, suggesting size-specific binding. In EMSA, neither protein bound to 180-nt and 21-nt ssRNAs at detectable levels. Sequence analysis revealed that P7 contains a conserved GW motif. Mutational disruption of this motif resulted in loss of suppression of RNA silencing and pathogenicity enhancement, and failure to complement the silencing suppression-deficient wheat streak mosaic virus. Collectively, these data suggest that P7 and P8 proteins utilize distinct mechanisms to overcome host RNA silencing for successful establishment of systemic infection in planta.