Inheritance of resistance to two-spotted spider mite and glandular leaf trichomes in wild tomato Lycopersicon pimpinellifolium (Jusl.) Mill.

Genetics of resistance to Tetranychus urticae Koch and of glandular trichomes of Lycopersicon pimpinellifolium accession TO-937 in a cross between susceptible L esculentum Mill. 'Moneymaker' and resistant TO-937 was studied in a greenhouse experiment. Parents, F-1, F-2, and two BC1 generations, interspersed with susceptible tomato plants to avoid negative interplot interference, were artificially infested. Mite susceptibility was evaluated by a rating based on plant capacity to support mite reproduction. TO-937, BC1 to TO-937, and F-1 were resistant, 'Moneymaker' susceptible, and the F-2 and the BC1 to 'Moneymaker' segregated. Resistance was controlled by a single dominant major locus, but modulated by unknown minor loci. TO-937 presented type IV glandular trichomes, their presence governed by two dominant unlinked loci. Type IV trichome density correlated to resistance; however, a causal relationship between type IV trichomes and mite resistance could not be definitively established. The relatively simple inheritance mode will favor successful introgression of resistance into commercial tomatoes from the close relative L. pimpinellifolium.