1990 Volume 56 Issue 2 Pages 213-218
A comparative study on levels of viral infectivity, yield, double-stranded (ds) RNAs and coat protein was conducted for the symptomless leaves (S), green areas (G) and yellow areas (Y) of mosaic-affected leaves from tobacco plants inoculated with an isolate of cucumber mosaic virus (CMV) containing no satellite RNA. Levels of CMV infectivity in S and G were very low (1-2% of Y), which agreed with extremely low virus concentration in S and G (less than 1% of Y). However, total amounts of dsRNAs in S and G were relatively high (33-43% of Y). Gel electrophoresis showed that Y contained almost equal amounts of all four dsRNA species, while S and G contained equivalent amounts of dsRNAs 3 and 4 but no dsRNAs 1 and 2. Levels of coat protein in S and G were also very low (1-3% of Y). Throughout the growth of the symptomless leaves, the amounts of dsRNA species and coat protein remained virtually constant. Periodic detection of dsRNAs from newly developed leaves at the shoot tip revealed that the amounts of dsRNAs 3 and 4 were generally constant, whereas dsRNAs 1 and 2 were detectable only in the mosaic leaves appeared before and after the period in which the symptomless leaves developed.