Spotted wilt disease of tomatoes in Japan
1976 Volume 42 Issue 3 Pages 287-294
Details
1976 Volume 42 Issue 3 Pages 287-294
Since 1972 an outbreak of a virus disease of tomato has been found in Nara Prefecture. The symptoms were characterized by yellowing and severe necrotic spots on leaves and necrotic streaks on petioles and stems. Necrotic symptoms were also observed on deformed fruits.
By sap inoculation test 30 species in 8 families out of 36 species in 11 families were found to be susceptible to the causal virus. The symptoms observed were pronounced necrosis in many of the susceptible plants, especially of Solanaceae. In epidermal strips of infected tomato and Datura stramonium, cellular inclusions were easily observed. The virus was also transmitted by a thrips, Thrips tabaci, but not through infected tomato seeds. In crude sap prepared with 0.1M phosphate buffer (pH 7.0) or distilled water, the thermal inactivation point of the virus was between 45 and 50C or 35 and 40C, the dilution end point was between 10-5 and 2×10-5 or 10-4 and 2×10-4, and the longevity in vitro was between 10 and 15hr or 5 and 10hr, respectively. Virus particles observed in leaf-dip preparation from diseased plants were found to be spherical, 70-90nm in diameter, presenting an outer layer structure when fixed with 0s04 vapor before negative staining with 2% PTA (pH 7.0). In unfixed preparations, most of the virus particles were deformed to various extents. ln ultrathin sections of the infected leaf cells of tomato, clusters of spherical virus particles of 70-90nm in diameter were frequently observed in cytoplasm enclosed in vesicles.
From the above mentioned results, the causal virus was identified as tomato spotted wilt virus (TSWV). This is the first record of the occurrence of TSWV in tomato in Japan.
