Submitted to: Archives of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2002
Publication Date: 5/8/2002
Citation: Hii, G., Pennigton, R., Hartson, S., Taylor, C., Lartey, R.T., Williams, A., Lewis, D., Melcher, U. 2002. Isolate-specific synergy in deisease symptoms between cauliflower mosaic and turnip-clearing viruses. Archives of Virology. July 2002, 147(7):1371-1384. Interpretive Summary: Turnip vein-clearing virus (TVCV) and cauliflower mosaic virus infect and cause symptoms in turnip. The symptom caused by TVCV is very mild. Synergistic symptom tate is characterized by severely reduced leaf size is observed when TVCV is combined with a specific isolate (Cabbage S) of CaMV to infect turnip, but not with isolate CM4-184. Analysis of Cabb S-CM4-184 chimeras indicated that the synergy is not caused by viral accumulation, but by subtle genetic interaction mapping to the ORF IV-ORF-V region of CaMV genome.
Technical Abstract: Simultaneous infection of a plant by two viruses can cause more severe disease than is caused by infection with either virus alone. Such synergy may be due to effects on the replication of one virus by the second virus or to other causes. The tobamovirus turnip vein-clearing virus (TVCV), itself causing almost imperceptible symptoms in infected turnips, exacerbated symptoms of infection of turnip by the Cabbage S isolate of the caulimovirus cauliflower mosaic virus (CaMV). The synergy in symptom production was most evident in a reduced size of leaves, providing an objective measure of synergy. In contrast, synergy did not occur when the CM4-184 isolate of CaMV was used in combination with TVCV. Both isolates of CaMV increased the level of TVCV accumulated in leaves. TVCV did not increase the level of the Cabbage S CaMV isolate. The use of Cabbage S-CM4-184 chimeras revealed that a region critical for isolate synergy in stunting was within the coat protein gene and/or the 5' one third of the reverse transcriptase gene. We conclude that the disease symptom synergy between TVCV and Cabbage S CaMV is not caused by altered levels of accumulation of the viruses, but instead reflects subtle genetic interactions mapping to the ORF IV-ORF V region of CaMV DNA.