Avaliação agronômica e resistência a pragas de híbridos de tomate com elevados teores foliares de acilaçúcares

Abstract

Foliar acylsugars are responsible to provide resistance against a wide array of tomato pests. Similarly, the Mi gene, which provides nematode (Meloidogyne spp.) resistance, also has shown to be effective against some of these pests. Acylsugar and the Mi gene, in isolation or in association, can contribute significantly for the control of pests through genetic resistance. High levels of acylsugars are present in some wild species, like Solanum pennellii, but recently they also became available, through genetic breeding, in commercial tomato lines. This article aims to evaluate the agronomical performance of precommercial tomato hybrids, which carry high foliar levels of acylsugar and/or Mi gene, as well as their degree of resistance to whitefly and spider mite. In order to produce commercial hybrids, 23 elite lines with low level of acylsugar were used as seed parents, and one line (TOM-760), with high acylsugar contents and carrier of the Mi gene, as male parent. Agronomic traits were evaluated (total yield, commercial yield, early yield, mean fruit mass, fruit shape, number of locus) as well as fruit quality traits (soluble solid level, number of days to reach the firmness 2.104.N.m2 and fruit color). Hybrid resistance to whitefly (Bemisia argentifolii) and spider mite (Tetranychus urticae) was also assessed. The hybrid TEX-412, with oblate shaped-fruit, showed the best production features and competitive fruit quality. Saladete group hybrids TEX- 458, TEX-459 and TEX-461 stood out for then production features and competitive fruit quality. High level of foliar acylsugar were shown to promote resistance to whitefly Bemisia argentifolii and to spider mite Tetranychus urticae. The Mi gene, or a closely linked gene, also provided a degree of resistance to whitefly, with incomplete dominance with relation to the pest. However, this gene was not effective in providing resistance to the two-spotted spider mite. The resistance effects against Bemisia argentifolii conferred by acylsugar are added to Mi gene effects. The AS-Plus technology, characterized by increased foliar acylsugar contents, can be effectively used to impart resistance to mites Tetranychus urticae and to the whitefly Bemisia argentifolii, and, in combination with the Mi gene, its action against the whitefly is potentialized.