Tritimovirus P1 functions as a suppressor of RNA silencing and an enhancer of disease symptoms

Authors

Brock A. Young, USDA-ARS
Drake C. Stenger, USDA-ARSFollow
Feng Qu, Ohio State UniversityFollow
T. Jack Morris, University of Nebraska-LincolnFollow
Satyanarayana Tatineni, USDA-ARSFollow
Roy French, University of Nebraska-LincolnFollow

ORCID IDs

Feng Qu

Date of this Version

2012

Citation

Virus Research 163 (2012) 672– 677.

Comments

U.S. government work.

Abstract

Wheat streak mosaic virus (WSMV) is an eriophyid mite-transmitted virus of the genus Tritimovirus, family Potyviridae. Complete deletion of helper component-proteinase (HC-Pro) has no effect on WSMV virulence or disease synergism, suggesting that a different viral protein suppresses RNA silencing. RNA silencing suppression assays using Nicotiana benthamiana 16C plants expressing GFP were conducted with each WSMV protein; only P1 suppressed RNA silencing. Accumulation of GFP siRNAs was markedly reduced in leaves infiltrated with WSMV P1 at both 3 and 6 days post infiltration relative to WSMV HC-Pro and the empty vector control. On the other hand, helper component-proteinase (HC-Pro) of two species in the mite-transmitted genus Rymovirus, family Potyviridae was demonstrated to be a suppressor of RNA silencing. Symptom enhancement assays were conducted by inoculating Potato virus X (PVX) onto transgenic N. benthamiana. Symptoms produced by PVX were more severe on transgenic plants expressing WSMV P1 or potyvirus HC-Pro compared to transgenic plants expressing GFP or WSMV HC-Pro.