Abstract
Resistance of tomato agaisnt TMV was examined by using various plant materials, such as callus tissues, protoplasts from callus tissues or leaves, leaf discs, cotyledons and intact leaves of resistant tomato plants carrying Tm-22 gene. TMV multiplication in these materilas was estimated by means of quantitative immunoelectrophoresis using FITC-conjugated antibody. An amount of TMV, after incubation of inoculated callus tissues on solid medium for 6 days, was much higher in callus tissues of susceptible tomato plant than of resistant plants. The difference in these two types of callus tissues was more distinct in the largest pieces of callus tissues than in smaller ones, which were produced when they were inoculated with TMV by shaking. In the smallest pieces of callus tissues, there was no difference between callus tissues prepared from susceptible and resistant plants. In protoplasts, there was no significant difference between resistant and susceptible plants. On the other hand, a significant difference was detected in leaf discs, cotyledons and leaves of both plants. These results indicated that resistance gene, Tm-22, of tomato against TMV functioned effectively in large pieces of callus tissues as well as leaf discs and other intact materials of tomato, but not in protoplasts.
