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Identification of Spanish Strains of Citrus Tristeza Virus by Analysis of Double-Stranded RNA. P. Moreno, Instituto Valenciano de Investigaciones Agrarias (IVIA), 46113 Moncada (Valencia), Spain; J. Guerri, and N. Mu?oz. Instituto Valenciano de Investigaciones Agrarias (IVIA), 46113 Moncada (Valencia), Spain. Phytopathology 80:477-482. Accepted for publication 31 October 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-477.

Double-stranded RNA (dsRNA) patterns of 24 Spanish isolates of citrus tristeza virus (CTV) representing a wide range of biological diversity were examined. Seven distinct patterns, differing by the number and/or position of the dsRNA bands, were obtained for the 24 isolates assayed. Both seasonal and host variation was observed on the recovery of the dsRNA. Greatest yields were obtained in spring and autumn from sweet orange and Dweet tangor. DsRNA recovery was not always correlated with virus titer estimated by enzyme-linked immunosorbent assay. Several strains showed host-induced variation of the dsRNA profile and, in some cases, seasonal variation. Virus titer and the amount of dsRNA recovered were not necessarily correlated with symptom severity on Mexican lime, nor could the dsRNA pattern observed be correlated with any specific biological characteristics (that is, symptom severity and aphid transmissibility). Some biologically similar CTV strains showed different dsRNA patterns, whereas other biologically different strains had the same pattern. A severe strain, T-388, recently introduced into Spain, showed a unique dsRNA profile that enabled it to be distinguished from local isolates. DsRNA analysis should be a useful tool for an eradication program in progress in Spain. Evidence for segregation of a CTV isolate by dsRNA analysis also was obtained.

Additional keywords: electrophoresis, strain segregation.