Tritimovirus P1 functions as a suppressor of RNA silencing and an enhancer of disease symptoms.
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.
United States Department of Agriculture, Agricultural Research Service, Lincoln, NE 68583, USA.
Brock A
BA
Young
Drake C
DC
Stenger
Feng
F
Qu
T Jack
TJ
Morris
Satyanarayana
S
Tatineni
Roy
R
French
D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D010935:Plant Diseases / Q000821:virology*; D017863:Potexvirus / Q000472:pathogenicity; D019176:Potyviridae / Q000201:enzymology / Q000472:pathogenicity*; D034622:RNA Interference; D013194:Staining and Labeling / Q000379:methods; D014026:Nicotiana / Q000821:virology; D014908:Triticum / Q000821:virology; D015678:Viral Structural Proteins / Q000378:metabolism*; D014774:Virulence; D037521:Virulence Factors / Q000378:metabolism*
D015678:Viral Structural Proteins; D037521:Virulence Factors; D049452:Green Fluorescent Proteins