VIEW ARTICLE

Genetics

Interaction of the asc Locus in F₈ Paired Lines of Tomato with Alternaria alternata f. sp. lycopersici and AAL-Toxin. S. D. Clouse, Department of Plant Pathology, University of California, Davis 95616, Present address: Plant Biology Laboratory, Salk Institute, P.O. Box 85800, San Diego, CA 92138; D. G. Gilchrist, Department of Plant Pathology, University of California, Davis 95616. Phytopathology 77:80-82. Accepted for publication 25 April 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-80.

Purified AAL-toxin and single conidial isolates of Alternaria alternata f. sp. lycopersici were used to analyze F₈ paired lines of tomato for their respective interaction with the asc locus. Reaction to the pathogen was inherited as a single locus dominant for resistance in a segregating F₉ population of 2,064 plants derived by selfing progeny tested F₈ asc⁺/asc plants obtained by intercrossing F₇ asc⁺ / asc⁺ and asc / asc full-sibs. Reaction to the AAL-toxin and the pathogen, assessed simultaneously on 390 F₉ progeny from a single F₈ asc⁺ / asc plant, showed no independent assortment for the two reactions. The parental (asc⁺ and asc), F₁ (asc⁺ / asc). F₉ (asc⁺ and asc), and F₈ (asc⁺ / asc) plants revealed three significantly different levels of toxin sensitivity, which were inherited as an incomplete dominant and corresponded to the genotype at the asc locus.