Variations in Pathogenicity and Double-Stranded RNA (dsRNA) Patterns of Citrus Tristeza Virus Isolate Induced by Host Passage
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AuthorMoreno, Pedro; Guerri, José; Ballester-Olmos, José F.; Fuertes-Polo, C.; Albiach, Remedios; Martínez, M. E.
Cita bibliográficaMoreno, A., Guerri, J., Ballester-Olmos, J. F., Fuertes-Polo, C., Albiach, R. & Martinez, M. (1993). Variations of Pathogenicity and Double-stranded RNA (dsRNA) Patterns of Citrus Tristeza Virus Isolated Induced by Host Passage. Proceedings of the twelfth International Organization of Citrus Virologists Conference, 8-15.
Four citrus tristeza virus (CTV) isolates obtained by natural infection of Mexican lime seedlings kept in the field were graft-inoculated into Smooth Seville orange plants. Five years later, sweet orange and Mexican lime seedlings were graft-inoculated with the original isolates maintained in lime or the sub-isolates kept in Smooth Seville orange. Variations in pathogenicity and/or dsRNA profiles were observed among some ofthe isolates and the corresponding sub-isolates. Several sub-isolates, differing by pathogenicity and/or dsRNA profiles could be separated from the field isolate T- 385, which was obtained from a symptomless sweet/sour orange tree. One of these, sub-isolate T-317, induced mild symptoms in Mexican lime, and was symptomless in Etrog citron, rough lemon, sour orange and Eureka lemon, but induced vein clearing and stem pitting in sweet orange. The sub-isolate in sweet orange, T-318, was graft or aphid-transmitted to Mexican lime (sub-isolates T-305 and T-305a, respectively). These three sub-isolates induced severe vein clearing, vein corking, stem pitting and stunting in Mexican lime, vein clearing and stem pitting in citron, rough lemon and sweet orange, and seedling yellows in sour orange, Eureka lemon or Duncan grapefruit. T-317 and T-318 had similar dsRNA profiles, whereas those of T-305 and T-305* were different. When T-317 was graft-transmitted from citron to Mexican lime and then to sweet orange, the dsRNA profile of the new sub-isolate was similar to that of T-305, but the sweet orange plants were symptomless. The variations in pathogenicity and/or dsRNA observed indicate that many field isolates of CTV are mixtures of different strains, some of which can disappear or be at low titer when passed through certain hosts.