Resistência à Mosca-Branca em tomateiro mediada por aleloquímicos, por tricomas glandulares e pelo gene Mi

Abstract

In tomato plant, one of the vegetables most grown in the world, the phytosanitary occurrence problems becomes a limiting factor for production, with pest’s occurrence such as whitefly (Bemisia tabacibiotype B). In this study the objective was to quantify the whitefly resistance in genotypes of tomato plant with different foliar contents of allelochemicals (acylsugar or zingiberene) and with gene Mi. Also, evaluate resistance to whitefly in tomato clones in function of the glandular trichomes presence. Two experiments were carried out: the first experiment included 15 genotypes with different foliar contents of the allelochemicals and with gene Mi; and in the second experiment 30 clones selected in relation to trichomes density, derived from the cross between TOM-684 (Solanum lycopersicum) and LA-1401 (Solanum galapagense). The experiments were carried out in a greenhouse in a completely randomized design (CRD), with one plant per pot and six replications,totaling 90 plants in the first experiment. For the experiment which aimed to evaluate the glandular trichomes effect, it was used one plant per pot with six and ten replications, totaling 110 plants. Genotypes with high acylsugar (AS) and zingiberene (ZGB) contents had lower oviposition and fewer whitefly nymphs’ number, when compared to the controls with low levels of these allelochemicals. The genotype carrying gene Mi, with no allelochemicals presence (TOM-684), and those carrying gene Mi with high content AS (TOM-759 and TOM-760), presented greater resistance to oviposition and fewer nymphs’ number in relation to the susceptible ones. However, the resistance level to whitefly mediated by AS and ZGB, individually or in combination, was greater than the resistance level mediated by the gene Mi. For the second experiment, the 16 experimental clones with high density of glandular trichomes and the accession LA-1401 presented, in general, high glandular trichomes density - type IV in both abaxial and adaxial faces, with less preference for oviposition and fewer nymphs’ number, when compared with the commercial control ‘Santa Clara’. Significant and negative correlations between oviposition and nymphs’ number, and glandular trichomes densities - type IV were found, evidencing resistance mechanism to whitefly.