Due to failures of infection after mechanical inoculation of begomovirus on tomato (Lycopersicon esculentum Mill.) plants, an efficient and reliable begomovirus inoculation method was developed using the whitefly vector (Bemisia tabaci). Virus acquisition was carried out using a 'Tube-cage', made of a polypropylene tube, containing one to two day-old whiteflies and a tomato plant apex infected with a begomovirus isolate. After 48 h of acquisition access period, inoculation was done using a 'Ring-cage', containing viruliferous whiteflies, attached to the abaxial side of the leaf of young tomato plants. 48 hours after acquisition, the whiteflies were eliminated and the inoculated plants were incubated for 28 days under greenhouse conditions. Three viruliferous whiteflies per plant were enough to cause infection in susceptible tomato cv. Viradoro. This procedure was applied to test the resistance of tomato line 486-1 (resistant line) in comparison with 'Viradoro' (susceptible cultivar). Dot blot hybridization confirmed the susceptibility of 'Viradoro' and the resistance of the line 486-1, showing the efficiency of this method for screening plants for disease resistance. This method is also a useful tool in detecting the presence of virus in inoculated (lower leaves) and in non-inoculated (upper leaves) in a given plant. Using this procedure, it was observed that the resistance of the line 486-1 probably is expressed in the inoculated leaf without virus translocation to the upper leaves.
Lycopersicon esculentum; inoculation; resistance; screening; geminivirus
