Abstract
In 1978-1980, three viruses were isolated from field-grown spinach plants in Hokkaido. These viruses were identified as bean yellow mosaic virus (BYMV), tobacco mosaic virus (TMV) and beet necrotic yellow vein virus (BNYVV) by the experiments based on host range, physical properties, vector relationships, particle morphology and serology. BYMV isolated from spinach showing vein necrosis had flexuous filaments of about 750nm in length, and was transmitted by aphids in a non-persistent manner. Infectivity of crude sap from the infected plants was lost by heating at 55-60C for 10 minutes, by diluting at 10-3-5×10-3, and by aging at 20C for 2-4 days. Antiserum against this virus positively reacted with P strain of BYMV (BYMV-P) in immunodiffusion test, and a spur developed between the precipitin lines to the virus and BYMV-P. The virus infected many leguminous and non-leguminous plant species and caused top necrosis on broad bean and pea. The results indicated that the virus was N strain of BYMV. A virus showing mosaic symptoms on spinach, having straight rods of 300nm in length, and infected many species of Cruciferae was isolated. Infectivity in crude sap from infected plants was lost by heating at 90-95C for 10 minutes and diluting at 10-4-5×10-4. Antiserum against the virus reacted clearly with a crucifer strain of TMV, TMV-C. From these results, this virus was identified as a crucifer strain of TMV. Another virus was isolated from spinach showing mosaic and yellows symptoms. This virus was rod-shaped particles of 100-390nm in length, and was transmitted by infested soil but not by aphids. In crude sap from infected plants, the infectivity was lost by heating at 65-70C for 10 minutes, by diluting at 10-3-5×10-3, and aging for 2-4 days at 20C. As the virus reacted with antiserum against BNYVV, it was identified as BNYVV.
