Artificial induction of a plant virus protein in transgenic tobacco provides a synchronous system for analyzing the process of leaf chlorosis

• Transgenic tobacco with dexamethasone-inducible CaMV Tav gene was generated.
• Induction of Tav transgene resulted in chlorosis within 7 days.
• Pathogenic changes therein suggest its similarity to virus-infected plant tissues.
• This system can be a good model to study molecular mechanisms of viral chlorosis.

The underlying molecular mechanism of chlorosis, a typical symptom of plant viral diseases, remains poorly understood. To establish an experimental system to determine the molecular changes during chlorosis, especially in the early phase, we generated transgenic tobacco plants expressing Cauliflower mosaic virus Transactivator/viroplasmin (Tav) under the control of a chemically inducible promoter. Induction of Tav resulted in visible chlorosis in ten days, a statistically significant decrease in chlorophyll content in two days, decreased expression of chloroplast protein genes, and abnormal thylakoid stacks, indicating that this system reproduces the common features of chlorosis in virus-infected plants.