Location: Wheat, Sorghum and Forage Research
Project Number: 3042-21000-033-15-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Dec 1, 2018
End Date: Nov 30, 2021
Cross protection or superinfection exclusion (SIE) is defined as the phenomenon whereby initial infection by one virus prevents subsequent infection by closely related viruses. The mechanism(s) of SIE are just beginning to be understood. This project aims at elucidating the mechanisms of SIE of plant RNA viruses using the reverse genetics systems of Wheat streak mosaic virus (WSMV) and Triticum mosaic virus (TriMV). WSMV and TriMV are members of the family Potyviridae, which encompasses more than 30% of known plant viruses and several members of the Potyviridae are economically important. The availability of green fluorescent (GFP)- or red fluorescent protein (RFP)-tagged infectious cDNA clones of WSMV and TriMV, co-infection of wheat with WSMV and TriMV, and SIE among the strains of WSMV in wheat will provide an excellent system to unravel the mechanisms of SIE. Advanced genetic tools will be used in combination with innovative techniques for studying the protein-protein interactions and ultra-structural characterization of individual viruses to define the mechanisms of SIE. It is anticipated that the project will advance general knowledge of the interactions between viral products and the mechanisms of SIE. Identifying viral proteins/sequences involved in SIE will facilitate the development of novel management strategies for wheat viral diseases. Goal 1. Identify WSMV sequences involved in SIE. Goal 2. Identify TriMV sequences involved in SIE. Goal 3. Define the mechanism of SIE.
Infectious cDNA clones of Wheat streak mosaic virus (WSMV) and Triticum mosaic virus (TriMV) will be used as expression vectors to express WSMV- or TriMV-encoded proteins in wheat. Wheat plants infected with TriMV or WSMV expressing WSMV or TriMV proteins will be used to superinfect with green fluorescent protein (GFP)-tagged WSMV or TriMV, respectively. Wheat plants expressing the P1, HC-Pro, P3, 6K1, CI, 6K2, NIa-VPg, NIa-Pro, NIb, and CP cistrons of WSMV or TriMV will be examined for superinfection exclusion by WSMV-GFP or TriMV-GFP, respectively. The requirement of protein or RNA sequence in SIE will be examined by introducing a series of frameshift mutations for continuous reading frame of unrelated proteins. The minimal sequences involved in SIE will be examined by deletion mutation analysis. Cellular localization of viral proteins involved in SIE will be examined under confocal microscope by fusing the GFP gene to the N- or C-terminus of SIE sequence. The proposed experiments should result in publishable research findings in a three year duration of the project, and will identify viral sequences with a potential application for the control of wheat viral diseases.