Tobacco Ringspot Virus Isolated from Crotalaria (Crotalaria spectabilis).

Abstract

Two causal viruses were isolated from crotalaria (Crotalaria spectabilis) showing yellow ringspot and mosaic symptoms. The first virus was identified with bean yellow mosaic virus. The virus was transmitted mechanically and also by Myzus persicae. The hosts of this virus were crotalaria, broad bean, bean, soybean and Chenopodium amaranticolor. In electron microscopy using dip method, long flexuous thread-like particles were observed, and the length of them was 700-800mμ. Juice from diseased broad bean leaves reacted positively with antiserum of bean yellow mosaic virus (Komuro and Tochihara, 1964) in a slide flocculation test. The second virus was identified with tobacco ringspot virus. The virus was transmitted mechanically and also by Myzus persicae. The host range of this virus was comparatively wide, namely, aster, zinnia, Nicotiana tabacum (Bright Yellow, Xanthi), N. glutinosa, petunia, okra, broad bean, crotalaria, bean, soybean, turnip, New Zealand spinach, Gomphrena globosa, C. amaranticolor, beet and others. Characteristic ring-like pattern symptoms were observed on N. tabacum (Bright Yellow, Xanthi), N. glutinosa, and Datura stramonium, and these symptoms had a tendency to be masked under high temperature conditions. This virus isolate showed some differences from the hitherto reported tabacco ringspot viruses in noninfectivity to cucurbitaceous plants and in the symptoms on soybean. In electron microscopy using direct negative stain methond, spherical particles of about 26mμ in diameter was observed. The virus in vitro withstood heating at 65°C for 10 minutes, dilution to 5, 000 and 7 day's aging at room temperature.
Kahn et al. (1963) reported that bean yellow mosaic virus was isolated from crotalaria, but the disease of crotalaria by tobacco ringspot virus has not yet been reported. This is also the first report in recognition of tobacco ringspot virus in Japan.