Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2004
Publication Date: June 11, 2004
Citation: Stenger, D.C., French, R.C. 2004. Systematic replacement of wheat streak mosaic virus hc-pro. American Phytopathological Society Abstracts. Phytopathology 94:S99. Technical Abstract: HC-Pro of Wheat streak mosaic virus strain Sidney 81 (WSMV-S81) was replaced with the corresponding cistron derived from four strains of WSMV (Type, TK1, CZ, and EB3), the tritimovirus Oat necrotic mottle virus (ONMV), the rymoviruses Agropyron mosaic virus and Hordeum mosaic virus., or the potyviruses Tobacco etch virus and Turnip mosaic virus. These HC-Pro proteins varied in amino acid sequence identity shared with HC-Pro of WSMV-S81 from high (WSMV strains at ~86-99%), to moderate (ONMV at 70%) to low (rymoviruses and potyviruses at ~15-17%). All chimeric viral genomes systemically infected wheat upon inoculation with RNA transcripts. HC-Pro replacements derived from tritimoviruses did not alter host range relative to WSMV-S81, and were able to systemically infect wheat, oat, and corn line SDp2. These results indicate that differences in host range among tritimoviruses, including the inability of ONMV to infect wheat or the inability of WSMV strains Type and EB3 to infect SDp2 corn, are not determined by HC-Pro. In contrast, chimeric viruses bearing HC-Pro replacements derived from rymoviruses or potyviruses were unable to infect oat or SDp2 corn. Collectively, these results indicate that HC-Pro from distantly related virus species of the family Potyviridae are competent to provide WSMV with all functions necessary for infection of a permissive host (wheat) and that virus-host interactions required for systemic infection of oat or SDp2 corn are more stringent. Changes in symptom severity or mechanical transmission efficiency observed for some chimeric viruses further suggests that HC-Pro affects virulence in WSMV.