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Etiology

Euonymus Chlorotic Ringspot Disease Caused by Tomato Ringspot Virus. C. W. Puffinberger, Former graduate student, Botany Department, University of Maryland, College Park 20742; M. K. Corbett, professor, Botany Department, University of Maryland, College Park 20742. Phytopathology 75:423-428. Accepted for publication 13 November 1984. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/Phyto-75-423.

During the spring, young leaves of Euonymus fortunei var. vegetus and E. kiautschovicus exhibited chlorotic rings and oak-leaf patterns. The causal agent was isolated, characterized, and identified as a strain of tomato ringspot virus designated TomRSV-Eu. The virus was transmitted by mechanical inoculation, dodder (Cuscuta campestris), grafting, and a nematode (Xiphinema americanum). TomRSV-Eu was mechanically transmitted to several euonymus cultivars and infected a wide range of experimental hosts but did not infect tomato plants or systemically infect tobacco. Properties of TomRSV-Eu in crude sap were: thermal inactivation of 59- 60 C for 10 min; dilution end point of 1:100- 1:1,000 in 0.01 M phosphate buffer, pH 7; and in vitro longevity of 24- 28 hr at 25 C. Purified virus preparations were infectious and had an ultraviolet absorption spectrum of a nucleoprotein containing 40% nucleic acid. Sucrose density-gradient centrifugation resulted in two light-scattering zones containing isometric particles 28- 30 nm in diameter. Particles from the bottom zone had a sedimentation coefficient of 131S and were highly infectious, whereas particles from the top zone had a sedimentation coefficient of 53S and were not infectious. TomRSV-Eu did not react with antisera to 11 other isometric viruses but did form a single confluent precipitin zone of identity with tomato ringspot virus in reciprocal gel double-diffusion tests.