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Etiology

Characterization of a Potyvirus That Causes Zucchini Yellow Mosaic. Vittoria Lisa, Istituto di Fitovirologia applicata del Consiglio Nazionale delle Ricerche, via O. Vigliani 104, 10135 Torino, Italy; Guido Boccardo(2), Giovanni D’Agostino(3), Giuseppina Dellavalle(4), and Mariangela d’Aquilio(5) (2)(3)(4)(5)Istituto di Fitovirologia applicata del Consiglio Nazionale delle Ricerche, via O. Vigliani 104, 10135 Torino, Italy. Phytopathology 71:667-672. Accepted for publication 24 September 1980. Copyright The American Phytopathological Society. DOI: 10.1094/Phyto-71-667.

A potyvirus, for which the provisional name of zucchini yellow mosaic virus (ZYMV) is proposed, was isolated from diseased zucchini squash (Cucurbita pepo) in northern Italy. It was sap transmitted to 15 herbaceous species belonging to seven different botanical families, and caused severe symptoms in zucchini, cantaloupe, and watermelon. The virus was transmitted nonpersistently by Myzus persicae. It was purified from C. pepo by extraction in 0.5 M K₂HPO₄ containing 0.02 M Na₂SO₃, 0.01 M DIECA, and 0.005 M EDTA, clarification with Freon 113, sedimentation by ultracentrifugation, and rate-zonal centrifugation in 10–50% sucrose gradients in 0.05 M sodium citrate containing 0.02 M sodium sulfite. The purified virus had an ultraviolet absorption spectrum typical of a nucleoprotein with low nucleic acid content and a buoyant density in CsCl of 1.323 g/ml. Homologous antisera had titers of 1:1,024 and 1:2,048, as determined by slide precipitin tests. The virus reacted with two sera to Italian isolates of watermelon mosaic virus 2, but not with a serum to an isolate from Florida. Antisera to ZYMV also reacted slightly against bean yellow mosaic virus. The virus was not serologically related to 11 other potyviruses. Its modal length was 750 nm. Pinwheels and scrolls were observed in the cytoplasm of infected C. pepo cells. Phenol-extracted RNA of ZYMV was infectious and migrated as a single homogeneous species in 2.4% polyacrylamide gels; its molecular weight was estimated at ~3 × 10⁶. Upon electrophoresis of viral protein in sodium dodecylsulfate-polyacrylamide gels, a single band of protein (estimated molecular weight 3.6 × 10⁴) was detected.