AGROINOCULATION OF TOMATO YELLOW LEAF CURL VIRUS (TYLCV) OVERCOMES THE VIRUS-RESISTANCE OF WILD LYCOPERSICON SPECIES

Accessions of the wild tomato species Lycopersicon chilense LA 1969 an d L. hirsutum LA 1777 which are resistant to tomato yellow leaf curl v irus (TYLCV) in field- and in whitefly-mediated transmission tests wer e agroinoculated with a tandem repeat of the TYLCV genome. Large amoun ts of viral DNA started to accumulate in the agroinoculated L. chilens e and L. hirsutum plants about 10 days after the agroinoculation. Yell owing and narrowing of the upper leaves were observed in the L. chilen se plants but no curling as in susceptible L. esculentum cultivars. Th e agroinoculated L. hirsutum plants showed typical yellowing and curli ng of young leaves. These findings indicate that TYLCV introduced by m eans of agroinoculation leads to the breakdown of natural resistance m echanisms which prevent the replication, spread and expression of symp toms in resistant tomato genotypes.