Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 29, 2013
Publication Date: January 7, 2014
Repository URL: http://handle.nal.usda.gov/10113/58234
Citation: Tatineni, S., French, R.C. 2014. The c-terminus of wheat streak mosaic virus coat protein is involved in differential infection of wheat and maize through host-specific long-distance transport. Molecular Plant-Microbe Interactions. 27:150-162. Interpretive Summary: Wheat streak mosaic virus (WSMV) is the most economically important virus infecting wheat in the Great Plains. In addition to wheat, WSMV can infect barley, corn and oats. Viral coat proteins serve many functions in almost every aspect of the virus life-cycle. Understanding the roles of coat proteins in the virus life-cycle could provide important clues for developing new management strategies by interrupting the disease cycle. In this study, we found that single amino acid changes in the coat protein had a dramatic effect on how WSMV infects corn, whereas these same amino acid changes had no effect on wheat. Furthermore, we showed that certain amino acid substitutions prevented virus entry into the vascular system of corn. Thus, resistance of corn to WSMV occurs through a different mechanism than WSMV resistance in wheat. These results suggest that transfer of virus resistance across plant species using coat protein-based methods by altering genes should proceed with caution. Additionally, WSMV coat protein mutants with single amino acid changes could be used to identify the role of coat protein in the transmission of WSMV by the wheat curl mite.
Technical Abstract: Multifunctional viral coat proteins (CPs) play important roles in the virus life-cycle. The CP determinants and mechanisms involved in extension of host range of monocot-infecting viruses are poorly understood. The role of the C-terminal region of Wheat streak mosaic virus (WSMV) CP in virus transport was examined by mutating six negatively charged aspartic acid residues at positions 216, 289, 290, 326, 333 and 334. All of these amino acid residues are dispensable for virion assembly, and aspartic acid residues at positions 216, 333 and 334 are expendable for normal infection of wheat and corn. However, mutants D289N, D289A, D290A, DD289/90NA and D326A exhibited slow cell-to-cell movement in wheat, which resulted in delayed onset of systemic infection, followed by a rapid recovery of genomic RNA accumulation and symptom development. Mutants D289N, D289A and D326A inefficiently infected corn with mild symptoms, while D290A and DD289/90NA failed to infect systemically, suggesting that the C-terminus of CP is involved in extension of virus host range. Mutation of aspartic acid residues at amino acid positions 289, 290 and 326 severely debilitated virus ingress into the vascular system of corn but not wheat, suggesting that these amino acids are involved in extension of WSMV host range through host-specific long-distance transport.