Evaluation of breeding tomato lines partially resistant to Tomato yellow leaf curl Sardinia virus and Tomato yellow leaf curl virus derived from Lycopersicon chilense

Twelve tomato (Lycopersicon esculentum, Mill.) advanced breeding lines derived from L. chilense and partially resistant to Tomato yellow leaf curl Sardinia virus (TYLCSV) were evaluated for their resistance to the species from Israel (Tomato yellow leaf curl virus, TYLCV). Two assays were carried out in two consecutive years, using agroinoculation and whitefly-mediated inoculation, respectively. Symptom severity, percentage of infection, and viral DNA accumulation (using molecular hybridization) were measured. In the first assay, the 12 breeding lines were agromoculated with both virus species. Resistance to TYLCSV was confirmed for the 12 breeding lines, but only 6 of them showed resistance to TYLCV. During the second assay these six breeding lines were whitefly-inoculated with TYLCV. All lines showed high levels of partial resistance to TYLCV consisting in attenuation and delay in time of symptom development and reduction in virus accumulation when compared with the susceptible control. Three of these lines even accumulated significantly lower amounts of viral DNA than the resistant controls 'Anastasia' and 'Boludo' hybrids. These lines also display good horticultural traits, appropriate for the protected growing system and for the fresh market requirements. These advanced breeding lines are base material for developing commercial hybrids highly resistant to TYLCSV and TYLCV.