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Etiology

Characterization of Potato Virus Y Strains Isolated from Pepper. K. M. Makkouk, Graduate Student, Department of Plant Pathology, University of California, Riverside 92502; D. J. Gumpf, Assistant Professor, Department of Plant Pathology, University of California, Riverside 92502. Phytopathology 66:576-581. Accepted for publication 11 November 1975. DOI: 10.1094/Phyto-66-576.

Five strains of potato virus Y (PVY) could be differentiated by their reaction on different indicator plants. Three strains (PVY-4, PVY-10, and PVY-82) produced symptoms on Nicotiana tabacum that resembled (with slight variation) those produced by the common type (PVY-NC), and one strain (PVY-36) produced symptoms of the necrotic type. Potato virus Y strains NC, 10, and 82 were serologically identical and also closely related to strains 4 and 36 which likewise were serologically identical. Cross protection tests showed that PVY strains NC, 10, and 82 protected almost completely against PVY-4 but only partially against PVY-36. Strain PVY-4 was transmitted more readily by aphids (Myzus persicae) than were strains NC, 10, and 82. Strain PVY-36 showed the lowest level of aphid transmission. Ultraviolet light absorption spectra of purified preparations of the five PVY strains were identical, with a minimum at 245 nm, a maximum at 260 nm, and a slight shoulder at 290 nm. The A₂₆₀:A₂₈₀ ratio varied between 1.22 and 1.28, and the A₂₆₀:A₂₄₅ ratio varied between 1.14 and 1.18 depending on the virus strain. All five PVY strains migrated anodically in agarose-acrylamide gel electrophoresis at pH 8.2. Strain PVY-36 migrated most rapidly followed by strains NC and 4, and strains 10 and 82 migrated more slowly and at the same rate.