Resistance to two-spotted spider mites Tetranychus urticae in tomato genotypes and their relationship with glandular trichomes, acylsugar contents and molecular markers

Abstract

The tomato is a crop subject to the high incidence of arthropod pests, so cultivars with good levels of resistance would be of great interest in the management of the crop, in which pest control has been carried out historically by chemical control. The wild species Solanum galapagense is promising for use in tomato breeding, because of its high level of resistance to insects, presumably associated with glandular trichomes. Our study aimed to assess the resistance to spider mite Tetranychus urticae in tomato genotypes obtained from an interspecific cross with S. galapagense and its possible association with the presence of glandular trichomes. We aim to confirm whether the relationship between QTLs (quantitative trait loci) and the presence of type IV glandular trichomes, previously detected in an F 2 population, holds in more advanced generations (F 3 and F 2BC1(1) ), and to determine the interrelationships between QTLs, type IV trichomes and acylsugar. The experimental F2 genotypes with high density of type IV trichomes and the access 'LA1401' showed smaller distances traveled by the mites on the surface of the tomato leaflet than either the F 2 genotypes with low density of type IV trichomes and or the checks ‘TOM-684’ and ‘Santa Clara’. In the advanced populations (F3 and F2BC1(1) ), the acylsugar contents were positively correlated with the type IV glandular trichome densities. The results confirmed the association of those QTLs with the acylsugar contents and presence of type IV glandular trichomes in generations F3 and F2BC1(1) . The selection of plants with higher density of type IV glandular trichomes is a safe criterion for indirect selection for resistance to arthropod pests mediated by acylsugars. InDel markers are effective to select individuals with high levels of acylsugars and high density of glandular trichomes in advanced populations from the cross between S. galapagense 'LA1401' and S. lycopersicum 'TOM-684'.