Resistance to Bemisia tabaci in tomato species and hybrids and its association with leaf trichomes

Abstract

Chemical insecticides comprise the most widely used method of tomato pest control. Genotypes resistant to pests such as the silver leaf whitefly Bemisia tabaci may contribute towards the decreased use of insecticides to protect the environment. Leaf trichomes play a role in imparting resistance to pests, and exploiting intraspecific and interspecific variability for leaf trichomes in the tomato gene pool is an alternative to speed up introgression of resistance into improved lines or cultivars. We assessed the levels of whitefly resistance and trichome morphology/density in an array of accessions of the tomato gene pool and their hybrids with a tomato cultivar. A commercial cultivar (S. lycopersicum cv. Redencao), six wild species accessions, two S. lycopersicum var. cerasiforme genotypes, and eight intra and interspecific F1 hybrids were tested. The accessions LA 1401 (S. galapagense), AF 19684 (S. peruvianum), PI 127826 (S. habrochaites var. hirsutum), PI 134417 (S. habrochaites var. glabratum), LA 716 (S. pennellii), and RVTC 03 (S. lycopersicum var. cerasiforme) genotypes showed a higher density of glandular trichomes and carried the highest levels of whitefly resistance than the commercial cultivar. Segregating generations from their crosses with the cultivar may be promising sources to select plants with both higher density of glandular trichomes and resistance to whiteflies. Populations derived from S. lycopersicum var. cerasiforme’ RVTC 03’, which is part of intraspecific S. lycopersicum variability, maybe a more convenient source of pest resistance than those derived from interspecific crosses to obtain pest-resistant tomato cultivars.