1966 Volume 32 Issue 4 Pages 221-226
Vaccination of tomato plants with an attenuated tomato strain of TMV (L11) affords good protection against infection with the virulent parent virus (L). The effects of time from vaccination (L11) to inoculation (L) are reported in this paper.
The sap of L11-infected tomato leaves diluted either 10 or 10, 000 times of leaf weight was used as the vaccine. The intervals between vaccination and inoculation were at 0, 1, 2, 4, 8, 24, 48 and 168 hours. The tomato seedlings were 13-18 days old when vaccinated. One of their cotyledons was inoculated with L11 and the other one with L, to test the degree of protection. The symptoms on the tomato seedlings were recorded as regards chlorosis, mosaic on leaves, stunting, and malformation of leaves, at intervals of 3 to 4 days after inoculation of L.
The plants inoculated with L alone began to show chlorosis 7 days after inoculation, followed by mosaic, and 5 days later they mostly showed these symptoms together with stunting. Only a few plants inoculated with L11 alone showed chlorosis and stunting. In the plants inoculated with L 1 to 8 hours after vaccination, 40 to 60 per cent showed chlorosis and stunting: even the plants simultaneously inoculated with L11 and L showed protection to a certain extent. The plants inoculated with L 24 hours or more after vaccination showed such a remarkable effect that chlorosis and stunting appeared only in 10 per cent of them.
Mosaic symptoms appeared more slowly in the plants vaccinated and inoculated with L after 24 hours or more, than in the plants inoculated with L alone. The mosaic was milder in all the vaccinated plants than in the non-vaccinated plants.
With the vaccine diluted 10, 000 times, the preventive effects were incomplete when the plants were inoculated with L 24 or 48 hours after vaccination, but with the interval of 168 hours the vaccination gave good results.
From the results of experiment on removal of cotyledon inoculated with the vaccine, it was estimated that the attenuated virus began to move from the inoculated cotyledon to other parts of the plant in 2 or 3 days after inoculation.
