Location: Corn, Soybean and Wheat Quality ResearchTitle: Identification of a maize chlorotic dwarf virus silencing suppressor protein
|Jarugula, Sridhar - The Ohio State University|
|Zhao, Yujing - The Ohio State University|
|Qu, Feng - The Ohio State University|
|Marty, Deemarie - Dee|
Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/25/2016
Publication Date: 4/1/2017
Publication URL: http://handle.nal.usda.gov/10113/5801853
Citation: Stewart, L.R., Jarugula, S., Zhao, Y., Qu, F., Marty, D. 2017. Identification of a maize chlorotic dwarf virus silencing suppressor protein. Virology. 504:88-95.
Interpretive Summary: Plant-infecting viruses usually encode proteins that block a major plant defense pathway against viruses, the RNA silencing pathway. Virus proteins that block this defensive pathway are called "silencing suppressor proteins" and have been identified in many plant viruses. In this manuscript, we report the identification of a protein from a U.S. corn-infecting virus, maize chlorotic dwarf virus (MCDV), that suppresses silencing defenses in plants. This is the first time this function has been identified in this or any related viruses that infect corn, rice, and other plants. These viruses all produce one large protein that is cleaved into mature virus proteins, probably by one or more virus-encoded protein-cutting enzymes, or proteases. We also showed the maturation by protease cleavage of the MCDV silencing suppressor protein. Together, this information helps us to understand how the virus interacts with and infects plants to cause disease.
Technical Abstract: Maize chlorotic dwarf virus (MCDV), a member of the genus Waikavirus, family Secoviridae, has a 11784 nt (+)ssRNA genome that encodes a 389 kDa proteolytically processed polyprotein. We show that an N-terminal 78kDa polyprotein (R78) has silencing suppressor activity, that it is cleaved by the viral 3C-like protease into 51 and 27 kDa proteins (p51 and p27), and that the p51 protein has silencing suppressor activity. Silencing suppressor activity of this protein is conserved in three divergent MCDV strains (MCDV-Severe, MCDV-M1, and MCDV-Tennessee) and the recently described waikavirus Bellflower vein chlorosis virus. However, no silencing suppression was detected for the orthologous protein of the waikavirus Rice tungro spherical virus, type strain (RTSV-A) or Parsnip yellow fleck virus (PYFV) from the genus Sequivirus in the same family. This is the first identification of a virus suppressor of RNA silencing for MCDV and for the genus Waikavirus.