Final report : pre-immunization of tomato seeds to protect against the whitefly transmitted tomato yellow leaf curl virus

The virus was purified and its protein and nucleic acid were characterized in great detail. Viral ssDNA was cloned and DNA probe was developed to detect the virus in infected tomato plants and other hosts with high degrees of sensitivity and accuracy. The whitefly Bemisia tabaci was shown to be the only vector of TYLC virus (TYLCV); the vector"s biology, epidemiology, and relationship with TYLCV were substantially investigated. The study clearly demonstrated that the whitefly could acquire the virus or other viral components through membrane feeding. The virus could persist in the whitefly and also pass through eggs. The virus was also found to infect some wild hosts. Seven mild strains of the virus were identified from naturally infected tomato. Tomato seedlings could be mass inoculated by regenerating plantlets from TYLCV-infected tissues or by the feeding of viruliferous whiteflies. Plants infected with mild strain performed well in the field as compared with those infected by severe strain. However, symptom suppression by mild strain was shown to be inconsistent presumably due to the instability or mixed population of the mild strain being used. (Author abstract, modified)