Breeding for resistance to begomovirus in tropic-adapted tomato genotypes

Abstract

Four tomato lines introgressed from Lycopersicon chilense were compared with the commercial F1 hybrids 'ARO 8479' and 'HA 3108', which are tolerant to Tomato yellow leaf curl virus, and the cv. 'Campbell 28' as a susceptible control. Resistance was evaluated by the use of grafted diseased scions as well as in a field trial where plants infected by viruliferous whiteflies and disease-free plants were transplanted in paired rows. The new lines LD 3, LD 4, LD 5 and LD 6 showed no disease symptoms after grafting or in the field trial. Virus accumulation at 60 days after transplanting was low in the infected plants: 0.09, 0.60, 1.00 and 0.50 ng, respectively. No fruit-set or yield losses were registered under the high temperature conditions prevalent in the trial, in which lines LD 5 and LD 6 were better adapted to tropical conditions. Viral DNA concentrations were over 1000 ng in the cvs. 'Campbell 28', 'ARO 8479' and 'HA 3108'. The last two are considered tolerant as they were asymptomatic or had mild symptoms, respectively, but achieved acceptable yields in the trial. By contrast, virus had a negative effect on fruit-set, number of fruit per plant and total yield in the cv. 'Campbell 28'.