Induction of PR-Proteins and Oxidative Isozymes in Tomato Genotypes Resistant and Susceptible to Tomato Mosaic Virus and Tomato Spotted wilt Virus

Tomato spotted wilt virus (TSWV) and Tomato mosaic virus (ToMV) are two of the most common viruses that threaten tomato crops in Egypt and worldwide. The purpose of this study was to investigate the role of PRs, and oxidative isozymes in the protection of tomato plants from oxidative damage induced by viral infection in 16 tomato genotypes. A total of 16 tomato genotypes were evaluated against TSWV and ToMV separately. Changes in the content of protein and defense enzymes were studied in tomato genotypes resistant and susceptible to TSWV or ToMV. The results of the investigation showed that 16 tomato lines gave different responses to infection with TSWV or ToMV [highly resistant (HR), resistant (R), moderately resistant (MR), moderately susceptible (MS), and susceptible (S)]. In this study, the total soluble protein profiles, polyphenol oxidase (PPO), and peroxidase (POX) isozymes of the healthy tomato plants and the TSWV or ToMV infected ones were estimated by electrophoresis in Polyacrylamide gel electrophoresis (PAGE). The results showed quantitative and qualitative differences in the number of bands among the 16 tomato genotypes. Thus, the protein content and isozyme activities were increased or decreased or not changed in inoculated tomato plants with TSWV or ToMV, compared with the un-inoculated plants, depending on the genotype, virus, and degree of resistance. On the other hand, it was found a negative or low-positive correlation between disease incidence and (protein content and isozyme activities). Therefore, it is important that to understand the defense strategy of plants against viruses and how tomato plants defend themselves from virus invasion. Therefore, tomato genotypes resistant to TSWV or ToMV could be used in the tomato breeding programs to prevent viral infection