Accumulation of Tomato Yellow Leaf Curl Virus DNA in Tolerant and Susceptible Tomato Lines. M. Rom, Department of Plant Genetics, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel. Y. Antignus, D. Gidoni, M. Pilowsky, and S. Cohen. Department of Virology, and Department of Plant Genetics, and Department of Virology, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel. Plant Dis. 77:253-257. Accepted for publication 8 September 1992. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-0253.

Four tomato lines (M-60, M-54, 1970, and 2950), an F₁ hybrid (TY-20) tolerant to tomato yellow leaf curl virus (TYLCV), and the susceptible cultivars 1651, 1630, 614-1, and 199-2 were compared for accumulation of viral DNA in TYLCV-infected plants. DNA was analyzed by either alkaline transfer or dot spot hybridization using a cloned viral DNA as a probe. Results obtained with either procedure indicated that in all tested lines viral DNA accumulation peaked at 12–15 days after inoculation. At this time, accumulation of viral DNA in the tolerant genotypes was 10–50% lower than in the susceptible ones. Viral DNA then decreased up to 50% in both the tolerant and the susceptible lines, and it remained at that level. Differences in viral DNA among the tested genotypes were found throughout the experiment, but differences were most pronounced when DNA accumulation was at a peak. Viral DNA accumulation was positively correlated to symptom severity. Thus, this approach may provide a useful means of selecting TYLCV-tolerant genotypes.