TOMATO BREEDING LINES RESISTANT AND TOLERANT TO TOMATO YELLOW LEAF CURL VIRUS ISSUED FROM LYCOPERSICON HIRSUTUM

Two tomato yellow leaf curl virus (TYLCV)-resistant plants from access ions LA1777 and LA386 of the wild tomato species Lycopersicon hirsutum have been crossed. The resulting resistant Fl plants were crossed wit h the domesticated tomato L. esculentum, and a series of selfing was p erformed. Al each generation, individuals were selected for resistance (no symptoms and undetectable viral DNA) and tolerance (no symptoms b ut with delectable viral DNA) following controlled massive and repeate d inoculations with viruliferous whiteflies. A stable BC1F4 line (deno minated 902) that does not segregate for resistance was obtained. This line does not support virus accumulation, even upon extensive whitefl y-mediated inoculation of young seedlings, and does not need protectio n with nets or insecticides. Another stable BC1F4 line (denominated 90 8) was tolerant to the virus. Both lines have good horticultural chara cteristics and bear 80- to 120-g red fruits. Analysis of segregation o f susceptibility, tolerance, and resistance during the BC1F1 to BC1F4 crosses indicated that tolerance is controlled by a dominant major gen e and resistance by two to three additive recessive genes. The resista nt and tolerant lines do not need to be protected by insecticides or n ets.