Gene pyramiding for elite tomato genotypes against ToLCV (Begomovirus spp.), late blight (Phytophthora infestans) and RKN (Meloidogyne spp.) for northern India farmers.

Abstract

Mega variety with multiple disease and pest tolerance is one of the major research objectives to protect the crop from biotic stresses in current scenario of climate change. Three tomato leaf curl virus resistance genes (Ty-1, Ty-2 and Ty-3), two late blight resistance genes (Ph-2 and Ph-3) and one root knot nematodes resistance gene (Mi-1.2) were pyramided from different donor parents with the help of marker-assisted backcrossing followed by phenotypic selection. During 2016-2017 (August-March), 100 lines of BC1F4 mapping population were evaluated against these diseases and pest screening. Punjab Chhuhara (a popular north Indian tomato cultivar) was used as a recipient parent that is susceptible for all these diseases and pest. Whereas the resistant parents included CLN3022F2-154-11-11-0 for tomato leaf curl virus, LBR-15 for late blight and NR-5 for root knot nematodes. The study results evaluated, 13 advanced backcrossed lines which possessed multiple disease and pest resistance with better horticultural traits over the parents as well as checks. This investigation showed that the introgression of Ty-1, Ty-2, Ty-3, Ph-2, Ph-3 and Mi-1.2 genes significantly improved the resistance against leaf curl, late blight and root knot nematodes diseases in selected advanced backcrossed lines of tomato. These improved multiple diseases resistant lines may play an important role in future pre-breeding tomato improvement projects.