تغییرات بیان ژن MYB33 در گیاه گوجه‌فرنگی آلوده به سویه‌های ویروس موزائیک خیار

Cucumber mosaic virus (CMV) poses a significant threat to tomato cultivation worldwide, causing substantial annual losses. CMV strains are divided into two subgroups, I and II, with subgroup I further divided into IA and IB. These strains infect over 1,200 plant species globally. This research aimed to analyze and compare the expression of the MYB33 gene in tomato plants infected with CMV subgroups IA and II. Initially, tobacco plants were used as propagative hosts. After symptom development, extracts from infected tobacco plants were inoculated onto the tomato plants. Samples were collected from tomato plants on specific days following the appearance of symptoms. Subsequently, PCR was used to confirm the presence of the virus. Real-time PCR analysis revealed that MYB33 gene expression in tomato plants infected with CMV-Fny increased significantly from 7 dpi (days post inoculation) to 14 dpi, peaking at 30 dpi before declining at 50 dpi. These results suggest an intensified response up to 30 dpi, but the reduction at 50 dpi indicates that MYB33 expression was insufficient against the virulent Fny strain, corresponding to the severe symptoms observed in the tomato plant. The tomato plants increased MYB33 gene expression to suppress the Fny strain up to the 30th day. However, severe symptoms indicate this response was inadequate against the highly pathogenic strain. By the 50th day, expression of MYB33 in CMV-Fny infected plants decreased. In contrast, MYB33 expression in CMV-LS infected plants remained consistently high across all days sampled, indicating its role in defending against the LS strain and correlating with milder symptoms in the tomato plants. The higher expression levels in CMV-LS infected plants suggest a stronger defensive response compared to CMV-Fny infected plants. This heightened response is likely due to the lower pathogenicity of the LS strain bacuase of the test was applied in a sensitive cultivar. Due to the more aggressive nature of the Fny strain, the expression level of MYB33 in plants infected with CMV-Fny on the seventh day is lower than in plants infected with CMV-LS. Consequently, the defense response in plants infected with CMV-Fny was less effective, suggesting a less successful defense mechanism in tomato plants against this more virulent strain.