VIEW ARTICLE

Etiology

Characterization and Ultrastructural Studies of a Nepovirus from Euonymus. R. C. Larsen, Department of Plant Pathology, University of Arkansas, Fayetteville 72701; R. C. Gergerich, and K. S. Kim. Department of Plant Pathology, University of Arkansas, Fayetteville 72701. Phytopathology 80:134-140. Accepted for publication 9 August 1989. Copyright 1990 The American Phytopathological Society.. DOI: 10.1094/Phyto-80-134.

A virus of Euonymus europaeus, causing leaf mottling, stunting, die-back, and witches?-broom, was discovered in northwest Arkansas. The virus produced ringspots and chlorotic local lesions and later became systemic in Chenopodium quinoa and Nicotiana rustica. The virus was seed transmitted in C. quinoa. Purified virus preparations exhibited three centrifugal components, and buoyant densities of virus particles were 1,481 and 1,500 g/cm³ for middle and bottom components, respectively. The virus particles were isometric and averaged 28 nm in diameter. The A_260/280nm ratio of purified virus was typically 1.9. The percentage of RNA was 42% in the bottom component and 36% in the middle component. Analysis of virion proteins by sodium dodecyl sulfate polyacrylamide gel electrophoresis showed a single viral protein with a relative mass (M_r) of about 53,000. Nucleic acids of virus particles analyzed under denaturing conditions by horizontal agarose gel electrophoresis consisted of two ssRNA bands of M_r 2.2 ? 10⁶ and 2.6 ? 10⁶, for RNA-2 and RNA-1, respectively. Ultrastructural examination of infected plants revealed cytopathic effects characteristic of nepoviruses. This virus is closely related serologically to the elm and the birch strains of cherry leaf roll virus and will be referred to as the Euonymus strain of cherry leaf roll virus.