Herança do teor de acilaçúcares em genótipos de tomateiro e sua relação com tricomas foliares e repelência aos ácaros Tetranychus evansi

Abstract

Acyl-sugars are allelochemicals responsible for the resistance of Lycopersicon pennellii ´LA-716´ to arthropod pests, and their deployment in breeding programmes may contribute to the development of commercial varieties with improved levels of pest resistance. The objective of this work was to determine the inheritance of acyl-sugar contents in tomato genotypes and its relationship to the presence of foliar trichomes and to repellence to spider mites Tetranychus evansi. The tomato population studied was a segregating (F2) population from the third backcross to L. esculentum after the original cross with L. pennellii ´LA-716´. Acylsugar contents were quantified with a spectrophotometric technique (Resende et al., 2002b). Data obtained were evaluated via tests hypotheses monogenic inheritance under several presumed degrees of dominance (Gomes et al., 2000), and the presence of a major gene was also tested under the maximum likelihard function (Silva, 2003). Foliar trichomes were identified and quantified in sample semi-permanent paradermic preparations (Aragão, 1998) and mite repellence was evaluated in a quick biotest assay (Weston & Snyder, 1990). Both methods of genetic analyses deployed indicated that high acyl-sugar contents are controlled by a single genetic locus under the action of a recessive allele with incomplete dominance. Evaluation of acyl-sugar contrasting genotypes from the segregating population indicated that acyl-sugar contents are not related to the presence of foliar trichomes, but are related to mite repellence levels. The results demonstrate the feasibility of indirect selection for pest resistance based on selection for high acysugar contents in breeding programmes.