SeleÃÃo para alto teor de acilaÃÃcares em genÃtipos de tomateiro e sua relaÃÃo com a resistÃncia ao Ãcaro vermelho (Tetranychus evansi) e à traÃa (Tuta absoluta). / Selection towards high acylsugars levels in tomato genotypes and its relationship with resistance to spider mite(Tetranychus evansi) and to the South American pinworm (Tuta absoluta).

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Selection for high foliar levels of allelochemicals has been proposed as a suitable strategy for breeding tomatoes for arthropod pest resistance. In the Lycopersicon pennellii accession LA-716, acylsugars exsudated by type IV glandular trichomes present in all aerial parts of the plant reportedly mediate resistance to arthropod pests. This paper intended to study the levels of resistance to two arthropod pests, the South American tomato pinworm (Tuta absoluta) and spider mites (Tetranychus evansi) in tomato genotypes selected solely on the basis of their foliar acylsugar contents. Plants with contrasting acylsugar contents were selected from population F3BC2 derived from the interespecific cross Lycopersicon esculentum âTOM-584âx Lycopersicon pennellii âLA-716â. Four high acylsugar genotypes (BPX-370E-30-380-68-6, BPX-370E-30-380-68-8, BPX-370E-30-275-11-7, BPX-370E-30-275-11-8) and seven low-acylsugars genotypes (BPX-370E-30-380-27-7, BPX-370E-25-271-29-2, BPX-370E-25-271-30-5, BPX-370E-25-271-30-8, BPX-370E-25-271-79-7, BPX-370E-30-275-70-2, BPX-370E-30-275-70-9) were selected. These genotypes were used in tests for resistance/ repellence to the arthropod pests,along with parental checks TOM-584 and LA-716. In Tetranychus spp. mite repellence tests, plants selected for high acylsugar contents behaved similarly to the resistant parent LA-716. Negative and significative correlations between acylsugar contents and distances travelled by the mites onto the leaflet surface indicated an association between the allelochemical and the levels of mite repellence. In the assay with the South American pinworm, these genotypes were evaluated for ovoposition ten days after infestation, and for leaflet lesion type and overall plant damage at four differents dates. The high acylsugar genotypes BPX-370E-30-380-68-6, BPX-370E-30-380-68-8, BPX-370E-30-275-11-7, BPX-370E-30-275-11-8 had good levels of insect resistance, similar to those found in LA-716. The increasing levels of resistance imparted by high acylsugar levels were more evident with increasing times of exposure to pinworm infestation. In the last evaluation date, acylsugars levels were highly and negatively correlated with pinworm damage. *The results indicated that selection for high acylsugar contents was effective in increasing the levels of arthropod resistance of tomato genotypes.

ASSUNTO(S)

Ãcaro praga melhoramento vegetal prage melhoramento genÃtico vegetal plant breeding controle genÃtico traÃa do tomateiro tomate tomato spider mites genetic control pinworm

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