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Effects of Strain, Host, Time of Harvest, and Virus Concentration on Double-Stranded RNA Analysis of Citrus Tristeza Virus. J. A. Dodds, Department of Plant Pathology, University of California, Riverside 92521; T. Jarupat, J. G. Lee, and C. N. Roistacher. Department of Plant Pathology, University of California, Riverside 92521. Phytopathology 77:442-447. Accepted for publication 29 August 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-442.

Major and minor double-stranded ribonucleic acids (dsRNAs) of citrus tristeza virus (CTV) could be detected and compared with confidence when all the dsRNAs purified from 1 to 2 g of infected citrus bark tissue were analyzed by polyacrylamide gel electrophoresis. Tissue from field or greenhouse-grown infected citrus must be in optimal condition for dsRNA analysis for this to be true. Four strains of CTV, selected to represent some of the biological diversity in the University of California, Riverside, collection of CTV isolates induced the accumulation of virus specific dsRNAs in Citrus sinensis (sweet orange), C. aurantium (sour orange), C. aurantifolia (Mexican lime), C. limon (lemon), C. paradisi (grapefruit), C. medica (citron), and C. excelsa. The most reliable dsRNA results were obtained from sweet orange, C. excelsa, and citron. Sour orange and grapefruit were the least reliable hosts for dsRNA analysis. The ranking of hosts for dsRNA quantity was generally similar to that determined for antigen titer of CTV in the hosts tested. The dsRNA profiles were characteristic for each strain, particularly when extracts were from the most reliable hosts for dsRNA analysis. Sour orange, grapefruit, and lemon had a tendency to reduce the number of dsRNAs and/or their relative intensity, as well as the quantity of dsRNA. A marked effect of time of year was observed, and CTV antigen and dsRNA were detected with difficulty when daytime temperatures were highest, which in Riverside is from June to September. The results of CTV antigen and dsRNA analyses were better at other times of the year. February to April was optimal. These results will be of value if dsRNA analysis is included in surveys for strains of CTV.