Evaluation of Tomato Inbred Lines Harboring Ty Gene(s) for Resistance Against Monopartite and Bipartite Begomoviruses

Abstract

The leaf curl disease caused by begomoviruses is a major constraint of tomato production in tropical and subtropical countries. The Ty-genes, present in wild tomato varieties, were found to be effective in developing resistance in plants against the begomoviruses. The present study evaluated the affect of six Ty-genes (Ty-1, Ty-2, Ty-3, Ty-3a, ty-5 and Ty-6) present alone or in combination, into fourteen tomato inbred lines, for resistance against monopartite and bipartite begomoviruses with betasatellite, using whiteflies in the greenhouse. The results indicated that ty-5 followed by Ty-2 and Ty-3 is most effective for developing resistance/tolerance in plants; however, these genes alone are not able to make the plant resistant to begomoviruses. The results also indicated that the tomato lines harboring up to three Ty genes (ty-5, Ty-2 + Ty-3, Ty-1 + Ty-2 + Ty-3) develop resistance against the monopartite begomovirus but were tolerant to bipartite begomovirus (severity score ≤ 2) at 15 days post-inoculation (DPI), and became susceptible thereafter, whereas the tomato lines harboring five Ty-genes (Ty-1 + Ty-2 + Ty-3 + ty-5 + Ty-6) found resistance to both the begomoviruses at 45 DPI. In conclusion, the increasing number of Ty gene in a single variety gradually increases the tolerance in plants to begomoviruses, and therefore, the strategy might be used to develop a hybrid which will be helpful in alleviating the losses due to begomoviruses.