Inheritance of acylsugar contents in tomatoes derived from an interspecific cross with the wild tomato Lycopersicon pennellii and their effect on spider mite repellence

Juliano T.V. Resende¹, Wilson Roberto Maluf¹, Maria das Graças Cardoso², David L. Nelson³ and Marcos Ventura Faria⁴

¹Departamento de Agricultura, Universidade Federal de Lavras (UFLA), Caixa Postal 37, 37200-000 Lavras, MG, Brazil

²Departamento de Química, UFLA, Lavras, MG, Brazil

³Departamento de Química Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil

⁴Departamento de Biologia, UFLA, Lavras, MG, Brazil

Corresponding author: W.R. Maluf

E-mail: wrmaluf@ufla.br

Genet. Mol. Res. 1 (2): 106-116 (2002)

Received April 4, 2002

Published May 15, 2002

ABSTRACT. Acylsugars present in Lycopersicon pennellii are responsible for the high levels of pest resistance often found in this wild tomato taxon. We investigated the inheritance of acylsugar contents in segregating populations of the interspecific tomato cross L. esculentum x L. pennellii and estimated correlations between leaflet acylsugar contents and the levels of mite repellence. Acylsugar contents were quantified with the Sommogy-Nelson colorimetric method in the acessions L. esculentum ‘TOM-584’ (P₁, low acylsugars), L. pennellii ‘LA-716’ (P₂, high acylsugars), in the interspecific F₁ (P₁ x P₂) and in the F₂ (P₁ x P₂) generations. Mite resistance was assessed by a repellence test. Broad-sense heritability of acylsugar contents was moderately high (h²_b = 0.476). Frequency distributions in the P₁, P₂, F₁ and F₂ can be explained by the action of a single major locus, with near-complete dominance of the L. esculentum allele for low-acylsugar content over the L. pennellii allele for high content. Indirect selection for high levels of acylsugars in leaflets led to correlated increases in the levels of mite repellency, indicating that acylsugars may be the main factor involved in mite resistance.

Key words: Tomato, Allelochemical, Acylsugars, Pest resistance, Trichomes, Spider mites, Tetranychus evansi, Lycopersicon esculentum, Lycopersicon pennellii