Characterization of Solanum sp. Lycopersicon section for density and types of leaf trichomes and resistance to whitefly and tomato pinworm

Abstract

Resistance genes to pests such as Bemisia tabaci and Tuta absoluta can be abundant in wild tomato genotypes. For breeding program initiatives, the characterization of the germplasm in terms of resistance to pests and related morphoanatomical characteristics is essential. Thus, the objective of this study was to evaluate the resistance of different accessions of species of Solanum sp., section Lycopersicon to B. tabaci and T. absoluta and establish a relationship with the types of trichomes present on the leaf surface. Whitefly oviposition, nymphs, and exuviae were investigated in 35 genotypes. On the leaf surface of the genotypes, glandular and non-glandular trichomes were identified and quantified. Based on the results, the genotypes were chosen for pinworm testing. Thirteen tomato genotypes were investigated, including Solanum lycopersicum var. cerasiforme, two accessions of S. lycopersicum, and ten wild accessions of Solanum sp., section Lycopersicon. At 7, 14, 21, and 28 days after infestation, eggs were counted on the abaxial surface of the leaflets, and the extent of damage caused by the tomato leafminer was determined using multivariate analysis and the area under the attack severity progress curve. Leaf trichomes of the 13 pre-selected genotypes were identified and quantified. The findings for the whitefly showed that wild genotypes were more resistant than the commercial ones due to the presence of trichomes, mainly glandular trichomes. According to principal component analysis, stronger materials in whitefly tests correlated more with the number of glandular trichomes. Finally, glandular trichomes positively correlate with the genotype's defense against pests. Solanum pennellii LA-716 and S. habrochaites var. hirsutum PI-127826 were the genotypes with the lowest number of oviposition and damage caused by the moth. This trait was also related to the higher density of glandular trichomes. The results show variability among accessions of the same species for trichome density and pest resistance. This information allows the choice of the best accessions among the species when defining the parents to be used in initial crosses of breeding programs.