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

Authors

Satyanarayana Tatineni, USDA-ARSFollow
Roy French, USDA-ARSFollow

Document Type

Article

Date of this Version

2-2014

Citation

Molecular Plant-Microbe Interactions Feb 2014, Volume 27, Number 2, pp. 150–162. http://dx.doi.org/10.1094/MPMI-09-13-0272-R.

Comments

U. S. government work.

Abstract

Viral determinants and mechanisms involved in extension of host range of monocot-infecting viruses are poorly understood. Viral coat proteins (CP) serve many functions in almost every aspect of the virus life cycle. The role of the Cterminal region of Wheat streak mosaic virus (WSMV) CP in virus biology 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 maize. However, mutants D₂₈₉N, D₂₈₉A, D₂₉₀A, DD_289/290NA, 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 maize, eliciting milder symptoms, while D₂₉₀A and DD_289/290NA failed to infect systemically, suggesting that the C-terminus of CP is involved in differential infection of wheat and maize. Mutation of aspartic acid residues at amino acid positions 289, 290, and 326 severely debilitated virus ingress into the vascular system of maize but not wheat, suggesting that these amino acids facilitate expansion of WSMV host range through host-specific long-distance transport.