Abstract
Isolates of tobacco rattle virus obtained from naturally infected tobacco plants in Japan were separated into two groups on the basis of their symptoms on aster plant, serological reaction and particle-length distribution. HSN group (HSN and IH isolates) gave systemic necrosis on aster plant, while MD-1 group (MD-1, TH, UD, CH-2, CH-3 and MH isolates) produced yellow rings and mottle. In serological tests, these two groups gave cross reactions. Differences were observed in agar geldiffusion tests and in titers in micro-droplet precipitin tests. Similarly, differences were also noted in particle-length distribution; HSN group gave a bimodal distribution with 180-190mμ and 70-80mμ particles, while MD-1 group was characterized by shorter particles having a length of 40-60mμ.
Among Nicotiana spp. tested with the different isolates, no immune plant was observed, though there were differences in susceptibility of the different species and cultivars. Vinca rosea appeared to be a good reservoir host of the virus.
