CHARACTERIZING THE DENSITY AND TYPE OF LEAF TRICHOMES IN TOMATO FOR RESISTANCE TO YELLOW LEAF CURL DISEASE

Abstract

Global tomato (Solanum lycopersicum L.) production faces a major threat of tomato yellow leaf curl disease (TYLCD), transmitted by the whitefly (Bemisia tabaci). However, the resistance to TYLCD can gain enhancement by managing the vector. In tomatoes, the trichomes act as physical barriers against whiteflies. Developing tomato cultivars with specific trichome types in higher density works as a promising alternative to insecticides. The presented study investigated the relationship between trichome types, their density, and resistance to TYLCD by inoculating the cultivated tomatoes with the whitefly transmission method. The trichomes’ analysis also succeeded under a compound light microscope, aiding the selection of cultivars with high trichome density and TYLCD resistance. A negative correlation appeared between the glandular trichome type VI density and TYLC virus (TYLCV) resistance. Highly resistant tomato accessions (KKU-T23157, KKU-T23160, KKU-T23163, and KKU-T23164) and moderately resistant accessions (KKU-T23152, KKU-T23154, and KKU-T23172) displayed all five types of trichomes, with type VI density of 32–55/mm² and 32.67–42/mm², respectively. Susceptible tomato cultivars had only three trichome types, with type VI density of 9–19/mm². The presence of high glandular trichome type VI density, Ty-2, and Ty-3 resistance genes contributed to the TYLCD resistance. These selected tomato cultivars proved valuable for future tomato breeding programs.